HVAC School - For Techs, By Techs (Bryan Orr)

Learn more about Refrigeration Technologies HERE.

In this short podcast, Bryan goes over energy transfer and heat, specifically specific heat.

BTUs per ton is a common measurement; a BTU (British thermal unit) is the amount of heat it takes to raise the temperature of one pound of water by one degree Fahrenheit. 12,000 BTUs per hour is equal to one ton in heating or cooling technology. It takes one “ton” of heat to melt a ton of ice, but we kept the measurement and terminology as we moved away from using ice in industrial refrigeration.

When it comes to specific heat, we have to remember that one BTU has a different heating or cooling impact on different substances. Most fluids have a specific heat lower than water, meaning that one BTU of heat will result in more heat transfer in that substance than water. Air is one such fluid that has a lower specific heat than water (0.24 vs. 1); it’s easier to heat air than water. However, the specific heat of vapors can change with temperature and pressure.

When we change a refrigerant from a liquid to a vapor in the evaporator coil, it will reach saturation before boiling. As the refrigerant boils, the temperature will stay the same because the absorbed heat will all contribute to the phase change as latent heat. Even though most refrigerants have low specific heat, direct expansion systems can still move a lot of heat because it takes a lot of latent heat to complete a phase change.

In other systems that don’t use direct expansion (using glycol or water instead), specific heat is more integral to the effectiveness of heat transfer because latent heat isn’t a factor in heat capacity.

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Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

In this short podcast episode, Bryan shares his top tips for fighting boredom at work. You can use these tips to help you get out of a rut if you don’t feel productive or get bored easily.

The first tip for fighting boredom is to see the art or creativity in your work. Even in the HVAC industry, there are plenty of opportunities for artisan skills and craftsmanship. When you see your work as an art that you need to refine, it’s easier to get engaged in your work and feel proud of it. That's especially true of tasks like duct strapping and brazing.

Another way to stop from getting bored is to do more things that challenge you. Being constantly challenged and being out of your comfort zone keeps you interested and can even spark a new passion.

Pursuing mastery allows you to focus on one particular skill or subject to become an expert. When you master a skill, you also become a marketable job candidate and can carve out a niche within your organization. Mastery is about going deep rather than wide, and more people will feel enriched by working towards mastery than others.

If you’re a social person, finding a community can keep you from getting bored. When you have a community, you will be around people who have the same interests and experience the same challenges as you. So, you won’t get bored from feeling alone.

Mentorship is another way to rekindle your passion. When you choose to invest in and guide less experienced people in the trade, you can feel a renewed sense of purpose in your work.

And if you’re REALLY bored, you can change everything up entirely and try something new.

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Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at hvacrschool.com/symposium/.

In this short podcast, Bryan talks about how to pay close attention to airflow issues and use your "spidey sense" when you're doing a visual inspection or commissioning a system. He also covers some causes of common airflow problems and some services and upgrades you can offer to your customers.

The skill of being able to use your senses and notice when something isn't quite right is a valuable one, especially when you're getting ready to set the charge. Not every technician has access to the tools to do a comprehensive airflow assessment, but every tech can use their senses to determine when something is wrong with the system airflow. Keep an ear out for whistling or other strange noises, and watch out for cabinet shaking, which may indicate an airflow problem. 

Airflow restrictions are also significant issues. Filter cleanliness (or lack thereof) and improper filter selection are very common causes of airflow issues, including high static pressure drop. Most filters should also not be doubled up (in series). Watch out for furniture blocking vents and registers that are partially (or fully) closed; shutting off registers is NOT a good strategy. Air movement throughout the building is also important, including the presence or absence of returns, open doors, etc., and these things affect MAD-AIR.

Watch out for things like leakage as well, which can be around the platform, in ducts around the equipment, and around vents or recessed lighting. 

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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In this short podcast episode, Bryan answers a listener-submitted question: what is the best brand of equipment for residential new construction?

A lot of people have their own personal preferences when it comes to brands, whether that's with equipment, tools, or even cars. However, when it comes to HVAC equipment, there are a lot of factors that come into play, especially as far as local support is concerned. Are the distributors and territory managers accessible? Reliable? Bryan's personal preferences deal a lot with American (or at least North American) manufacturing and the strength of their local support in the Central Florida market.

Some manufacturers have excellent base products but weak product lines, and others have weak base products but great specialized equipment. These judgments come from personal experience, and that's especially true of large manufacturers. Bryan recommends taking a measured, slow approach to products you deal with and then choosing the one that works best for your market and customers. You may find yourself gravitating towards equipment with certain components (like Copeland compressors, for example). You may gravitate towards manufacturers that take feedback about their products and have great local support. The "best brand" really depends on your experiences, values, and business needs.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android

In this short podcast episode, Bryan shares some strategies for teaching communication confidence, which may come in handy if you have newer techs who feel nervous or struggle to communicate with other people.

The main way to build confidence is to get them to talk in the first place. Scripts and roleplay scenarios during training can help get people used to speaking and give them a reference. Whether we're in sales or not, we have to share information and complete business transactions. Roleplaying those conversations in a controlled, familiar setting allows your more timid team members to put in the reps.

The youngest generation in the workforce tends to be exceptionally uncomfortable talking compared to others; they often prefer to communicate via text. These techs can learn a lot from spending time with customer service representatives (CSRs), especially in difficult situations with upset clients. Then, you can address the non-verbal cues that also play a massive role in in-person communication.

At Kalos, we have developed software that allows people to record voice memos that are then transcribed. We combine this with soft skills training to help build confidence in our team members so that our leaders can understand what their teams are doing. Communication also starts at the top, so leaders must be honest with themselves about their communication skills and how well they regulate emotions and positively convey information. Leaders are also ultimately the ones who are responsible for understanding their team's communication gaps and creating the guidelines.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

Subscribe to our YouTube channel. 

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In this short podcast episode, Bryan talks about locked compressors and hard starts. He explains what actually happens when a compressor locks and covers when and how to use hard starts appropriately. 

Locked compressors are compressors that trip on overload during startup; they're considered "locked" because the rotor doesn't turn inside the stator and generates heat instead. The overload opens, but the compressor shell typically does not heat up very much when the overload opens. 

When you have a locked compressor, you need to start investigating the root cause with a thorough visual inspection. Then, check the run capacitor. A hard start kit helps you get the equipment working, but we should make sure we've addressed underlying electrical issues or installation conditions before installing a hard start kit. If the unit is old, then we may use a hard start as a temporary solution until the customer can purchase a new unit. In any case, it's best to use a factory hard start if the system requires it, but it's okay to use an aftermarket hard start kit to get an old system to run.

Hard start kits consist of a start capacitor in series with the start winding, which moves more current into the start winding and decreases the time it takes to start the compressor; lower current readings indicate a faster amperage drop, as most ammeters read timed average values. The potential relay needs to open to take the start capacitor out of the circuit so that we don't continuously apply additional current to the start winding, which hurts the compressor over time. The hard start kit is not a silver bullet that solves all problems, and we need to know when to use them and how to use them appropriately.

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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In this live podcast episode, we discuss viruses, bacteria, and fungi. We also explain how they interact with HVAC equipment, their effects on indoor air quality, and how businesses can protect their customers and employees.

Since we work with the public, we can minimize the risk of viral transmission by keeping our distance between others and avoid handshakes and other forms of contact. However, we also have to respect the feelings of the customers we're serving.

Many people confuse viruses, bacteria, and fungi (mold). All particles are small and would typically pass right through a MERV-8 filter; you typically need MERV-11 or better to catch all three. While our equipment can harbor those particles, the equipment can't create them. While bacteria and fungi can propagate on their own, viruses need a host to propagate.  Viruses can go airborne, but they only grow and propagate inside our bodies. So, we don't need to worry about minimizing growth on surfaces or inside HVAC equipment.

We make it harder for bacteria, fungi, and viruses to survive by keeping the relative humidity between 30% and 55%. That is part of the reason why certain viruses become prominent seasonally, though our own immune systems are also a factor.

Probiotic cleaners also exist to attack biofilm on surfaces. To achieve that goal, probiotic cleaners promote good bacterial growth to fight the bad growth we want to eliminate. We may expect probiotic technologies to improve even more in the future. However, those won't affect viruses strongly because viruses don't GROW in equipment.

We also discuss:

• Virus transmission
• Masks and gloves
• Mobile air scrubbers
• HVAC technicians as essential workers
• Microns
• Legionella
• COVID-19 vs. influenza
• HEPA and activated-carbon filtration
• Photocatalytic oxidation (PCO), bi-polar ionization, and UV lighting
• Is oxidization effective?
• Good vs. bad bacteria and probiotic cleaning

Learn more about Refrigeration Technologies HERE.

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Moe Hirsch joins the podcast to discuss the hydronics side of the industry, particularly focusing on Dan Holohan’s Pumping Away and exciting developments in the hydronics market, especially regarding electrification.

Pumping Away is many people’s entry point to hydronics. It contains some good basic information about boilers, especially when it comes to learning about the pressures involved in pumping and how the components manipulate pressure throughout the system. 

Boilers use many of the same fundamentals as compression-refrigeration HVAC systems; pressure drops are similar, as are phase changes in steam boilers. Boilers also employ pumps instead of compressors, but the processes are similar. 

The pump or circulator makes a pressure differential within the boiler, which adds pressure to the circulator outlet and results in negative pressure on the suction side. However, problems like air bubbles and magnetite buildup can negatively impact performance.

The electrification side of the boiler industry is exciting, especially because of the relative safety of electricity compared to combustible fossil fuels. However, electrification comes with its own set of concerns, especially when natural gas prices are low. In some markets, electrical grids also haven’t caught up with the demand for electricity yet.

Moe and Bryan also discuss:

• Moe’s recent work in the industry
• Changes in boiler infrastructure over the years
• Pumping away from the boiler vs. pumping at the boiler
• Pressure’s role in boiler systems
• Similarities between parallel racks and boilers
• Challenges with ECM circulators
• Evolution of boiler motors and controls
• Magnetic and hydraulic circulation
• Low-temperature heat pumps with radiant heated systems
• Moe’s ideal HVAC system
• Natural gas health and safety risks (carbon monoxide)

To learn more about what Moe is doing, check out turnupthecomfort.com or contact Moe directly at info@turnupthecomfort.com. 

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In this episode of HVAC School, Bryan talks to his sons about basic electrical theory.

Electrical theory normally requires trigonometry, calculus, and all of those fun maths. However, the basics are so easy that a 12 and 14-year old can figure it out. Electrical theory follows many of the same principles as thermodynamics—however, electrical theory concerns charges rather than heat. Conductors and insulators behave similarly with electrical charges as they do with heat.

Ohm's and Watt's laws establish what volts, amps, power, and resistance, and they explain the relationships between those units. However, magnetism can add a bit of confusion to those equations. We drive motors with inductive loads, making Ohm's law seem invalid, but the magnetism resists itself, which goes unnoticed on ohmmeters. That is untrue of DC motors, and Ohm's and Watt's laws will appear to check out under most circumstances.

An electrical component can fall into three main functional categories: power source, switch, or load. If something doesn't fall into one of those categories, it merely adds resistance. The power source could be a transformer, which provides homes with power from the power company (and goes from a higher voltage to a lower one that our appliances can use). A switch opens/closes or rewires an electrical path, and a load is what does the work.

That's the short of it, but it's still pretty easy.

Join Bryan and his sons as they talk about:

• Differential charges
• Electromotive force
• Ohm's law
• Volts, Ohms, Amps, and Watts
• Electrical paths
• Conductors and insulators
• Resistive and inductive loads

And much more...

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In this podcast episode, Bryan and Trevor Matthews from Emerson talk through scroll compressors in commercial refrigeration equipment.

Scroll compressors are not a monolith; although they all function similarly, they have different fine details and manufacturing protocols by application. Low-temp, medium-temp, high-temp, and A/C scroll compressors each have unique designs, operating conditions, and service considerations.

Copeland has a medium-temp scroll compressor line (ZB and ZS) for medium and high-temp applications. They also have a low-temp line (ZF). Within those lines, there are also small displacement and large displacement compressors, advanced scroll temperature protection devices, and other unique features.

Since scroll compressors are prone to thermal overload, some Copeland compressors have advanced scroll temperature protection devices. These devices help redirect the discharge gas to the suction gas, which gets the compressor to trip out on thermal overload more quickly. In cases when you're tempted to condemn the compressor, shut it off and let it cool down before you jump to conclusions.

The compression ratio is the main difference between A/C and refrigeration scroll compressors. A/C scrolls can handle a compression ratio of 11:1. Conversely, refrigeration scrolls can handle 26:1 compression ratios.

Copeland scroll compressors also have electronic controls. When setting up these controls, you need to keep the scroll compressor type and special features in mind, including temperature protection devices. In other words, you can't set up a low-temp compressor the same as a medium-temp and so on.

Bryan and Trevor also discuss:

• Differences across Copeland scroll compressors
• Low-temp vs. medium-temp vs. high-temp refrigeration
• Copeland compressor nomenclature
• Compressor pump down
• Proper vacuum
• CoreSense diagnostics
• Vapor injection and compressor capacity
• PTC (positive temperature coefficient) thermistors
• Using AE bulletins as tools
• Crankcase heaters and other accessories

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast, Bryan talks about oxidation and all the buzz behind “magical air-cleaning oxides” and other similar IAQ products.

Oxidation is the loss of electrons, and reduction is the gain of electrons; oxygen commonly loses electrons. Rusting is a common example of oxidation; it happens when iron and oxygen interact in air or water. Metals that are more likely to react with oxygen (or corrode) are “less noble” than more noble metals. Less-noble metals, known as anodes, are sometimes used sacrificially to prevent the oxidation of nobler base metals, known as cathodes.

While iron oxidation results in corrosion, some IAQ products use the process to bind oxygen molecules to unwanted substances. The IAQ products that use oxidation use the natural tendency of oxygen to lose electrons when bonding with other molecules. Ozone is a common agent of these IAQ products because an ozone molecule is very unstable and has three oxygen atoms, meaning it combines with other molecules via oxidation; it stabilizes other unstable molecules. Ozone, however, also reacts similarly with cells in our respiratory system and can cause irritation. 

In our industry’s efforts to reduce the negative effects of COVID-19 viruses, oxidation has generated a good deal of interest. Nowadays, some IAQ products use smaller amounts of ozone or use activated carbon to catch ozone before it enters the conditioned space. Many manufacturers that use oxidation as a strategy use other ion-based oxidizers, just not ozone. Some of these oxidizers can break pollutants into aldehydes and other chemicals that may harm our bodies.

If you want to learn more, you can read Oxidizers and What It Has to Do With COVID-19.

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

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Don Gillis joins us again to talk more about common types of CO2 systems and how they differ

In this episode of the HVAC School Podcast, Bryan Orr and Trevor Matthews delve into the importance of setting goals, focusing on them, and taking actionable steps to achieve them. They emphasize that goal-setting is crucial for personal and professional growth and that it requires introspection, prioritization, and sacrifice.

Trevor shares his experience of setting a goal to buy his first house and how writing down the specifics, such as the number of bedrooms and bathrooms, helped him achieve that goal within a few years. He stresses the need to start small, with easily achievable goals, and then gradually build up to larger, more ambitious ones.

Bryan and Trevor also discuss the importance of finding your "why" – the deeper motivation behind your goals – as it provides the drive and determination to stay focused and overcome obstacles. They suggest techniques like the "five levels of why" and creating vision boards to help clarify and visualize your goals.

Here are some key topics covered in the podcast:

·        The importance of assessing what you truly want and setting clear goals

·        Techniques for finding your "why" and staying motivated

·        Prioritizing tasks and managing distractions to maintain focus

·        Setting short-term and long-term goals, both personal and professional

·        The power of small wins and positive reinforcement

·        Investing in yourself and taking ownership of your career growth

·        Managing expectations and aligning your goals with your employer's

·        Overcoming the mindset of waiting for the "right" time to start

·        Practical strategies like scheduling, time-blocking, and budgeting to achieve financial goals

Overall, the podcast encourages listeners to take control of their lives, continuously learn and grow, and make consistent progress toward their goals, no matter how small the steps may seem.

Check out Trevor's Refrigeration Mentor program at https://refrigerationmentor.com/.  

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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• Two-pole and three-pole contactors
• Resistive heat
• Operating A/C and heat pumps in low-ambient conditions
• Ohming compressors
• Jumpering in place of a single-pole contactor
• Wire sizing
• Loud thumping when the unit shuts off
• Trickle current during the compressor off cycle
• Power factor, reactive power, and actual power
• Low-resistance circuits
• Capacitor purposes, wiring, and sizing
• Small charge and flood back prevention
• 3/8" lines

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Jaden Lane joins us to discuss some best practices when using an air flow hood. She also explains how the Dwyer Smart is innovating in the hood space.

An air flow hood is an excellent tool, but we can't just assume that it'll work correctly in any system. Various vents and diffusers can cause different flow patterns to reach the hood, so you can get an incorrect reading if the flow hood is not aware of the flow pattern. Unless we give the hood background on what's going on in the duct, there's no way the hood will know the correction factor to give you the correct reading for the conditions in the duct. You can adjust smart flow hoods to compensate for inaccuracy factors.

Hoods are like big canvas skirts that you place over a vent, and there's a flow grid at the bottom. As air moves through the hood, the grid takes airflow readings. There are pitot arrays that act as traverse points on a duct traverse; these arrays take multiple measurements and give you an average. These devices work better when the air is a bit turbulent. If you doubt your measurement, you can also try the hood in different 90-degree orientations (but keep it centered).

Dwyer does a lot more than just make test instruments. They have a rigorous testing process for their products; their products can also work as permanent installations within buildings, not just tools for technicians.

Jaden and Bryan also discuss:

• Dwyer products, including the Magnehelic
• Vent vs. grille vs. register vs. diffuser
• Computational fluid dynamic analysis and other test methods
• Calibration vs. zeroing
• Predictive balancing
• Choke and backpressure
• Vane and hot-wire anemometers

Check out Dwyer at dwyer-inst.com.

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Learn more about Refrigeration Technologies HERE.

Check out more about Infinitum and its new motor technologies at infinitumelectric.com.

Learn more about Refrigeration Technologies HERE.

Bryan discusses impostor syndrome, what it is, and how it may actually be useful for us.

When we feel that we’re frauds and that others wouldn’t like to be led by us if they knew how much we don’t know, we’re experiencing impostor syndrome. Contrary to what others might believe, impostor syndrome isn’t all that bad and may even be necessary for a healthy self-image.

On the other side, we have the Dunning-Kruger effect, which is when people are confident in the things they have very little actual knowledge of. They think they’re experts and close themselves off to other sources of knowledge. On the other side of the Dunning-Kruger effect spectrum, true experts are acutely aware of what they still don’t know. We would be wise to know what the edges of our knowledge are and give others a chance to share their expertise when we reach those limits.

When people learn more about a subject, they become much more aware of what they don’t know. Wisdom comes from knowing what you don’t know. However, if you feel that feeling of inferiority, you can still share the knowledge you have while seeking feedback and deferring to others who know more than you. (That’s especially true of Bryan, who has a summary knowledge of industrial refrigeration and defers to others who know more about it.)

In the end, we’re seeking authenticity and self-awareness. Rather than avoiding impostor syndrome, we can embrace it and understand how it can lead to self-awareness, wisdom, and especially self-improvement. “Fake it till you make it” can only help you up to a certain point.

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Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

In this episode, Ruth King shares some of her top insights on how to create a maintenance program if you don't have one. She teaches us to recognize a broken program and fix it.

The maintenance component of your company will be the part of your business that allows you to grow your business profitably. If you don't believe in maintenance agreements, your customers won't believe in those maintenance agreements either. Without maintenance agreements, your company will have sharply different slower times and busier times. You'll likely have to pay employees to stay in slow times, and it is not very profitable.

Getting a maintenance agreement plan in motion is as easy as getting a maintenance agreement form. Inform your customers of the benefits of maintenance (saving money on utility bills, extending equipment life, etc.). Then, offer it to your customers; you don't even have to make it sound like a sales pitch. Some of your existing customers will almost surely agree to the maintenance agreement.

When you enroll someone in a maintenance agreement, it is a good idea to put that money in a separate savings account. The cost of performing the maintenance can be taken out of that savings account, but you would have ideally already set some money aside solely for operation costs. To make sure you're at least breaking even on your maintenance agreements, you must make sure you factor in hourly pay, cost of goods sold, and overhead costs. You can calculate overhead costs by checking the previous year's operating expenses and dividing that by your billable hours.

If you are interested in Ruth's maintenance program course, you can find out more HERE. Be sure to use the offer code HVACRS (with all caps) to get a 10% discount on all her products.

This episode is very exciting to me because we get to have Dr. Allison Bailes on the show. Today, he shares his knowledge about friction rate and duct design. Allison got his start teaching college-level physics before getting into the building design industry.

If you have a forced-air system that blows heated or cooled air through a duct system, that blower creates a pressure difference. Some of the pressure is used up on the filter, registers, and dampers, so you will see pressure drops. Anything left over is the available static pressure, which pushes air through the ducts. When you do a duct design, you must account for pressure drops and your blower's static pressure rating.

When designing a duct system, you want to minimize friction as much as possible. Counterintuitively, you want a high friction rate. Friction rate refers to the availability of static pressure compared to friction provided by the effective length, not the total amount of friction. Fittings significantly impact your total effective length. By extension, fittings can have a major impact on friction. In flex duct designs, the turns add additional resistance.

Oversizing often happens due to poor load calculation. While you increase capacity with an oversized system, there are plenty of drawbacks. The capacity will rarely match the load, you may spend too much on the equipment, have ineffective dehumidification, and you will deal with short cycles, which lead to comfort problems.

Allison and Bryan also discuss:

• Home energy ratings
• Equivalent length and total effective length
• Flex duct design
• Seasonal runtime
• Surface area challenges
• Unconditioned spaces
• Filtration

To find out more about everything Dr. Bailes has to say about building performance and duct design, visit his site at: https://www.energyvanguard.com/blog 

Learn more about Refrigeration Technologies HERE.

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Sam Myers with Retrotec talks to Bryan about pressures in the home and why they matter for HVAC solutions at IBS 2022.

Technicians focus a lot on ductwork and airflow, but many of them don’t focus on how the building envelope impacts HVAC performance. A lot of the HVAC equipment’s performance is affected by the push and pull of air caused by leaky areas in the building envelope.

If you have a room with too much air and another room with too little, you will have unbalanced pressures. Unbalanced pressures may result in discomfort and latent load issues, especially when unconditioned air is pulled in through the attic. Sealing the envelope well and using dampers as necessary can minimize the comfort issues caused by pressure imbalances in the home.

Instead of just using manometers for static and gas pressure, we can also use high-resolution manometers under doors to pick up pressure differences. However, the manometer MUST be high-res to pick up those subtle (but palpable) differences in pressure. A blower door is also a great tool, especially when you use it with a thermal imaging camera; the blower door amplifies the temperature effects that a thermal camera will detect, especially if you also have a good delta T.

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Joe and Eric join us, and we have a general conversation about small self-contained refrigeration units, including residential and commercial. Small refrigeration includes self-contained reach-ins and small walk-ins. These units typically use capillary tube metering devices.

Some of the biggest failures that occur in small refrigeration systems happen because of dirty condensers and user error (leaving doors open, etc.). You'll also want to check that the fans are working, the compressor is running, the coil is free of ice, and that the airflow isn't blocked. Inspection is the key, and gauging up is typically a last resort.

Refrigeration temperature measuring strategies can vary wildly by application. For example, open cases measure discharge air temperature. Systems with enclosed boxes (like walk-ins) typically sense return or box temperature. Small reach-in systems also typically have dial cold controls in a challenging location: buried at the end of the evaporator. There are straight and curly cold controls, but new equipment has made a shift towards electronic controls.

On small refrigeration units, we don't usually see start capacitors or hard start kits; however, we do see PTC relays and thermal overloads.

Domestic refrigerators also count as small refrigeration. They have independent controls that move air from the freezer to the refrigerator section of a normal household fridge; there is usually no cooling apparatus in the refrigerator. In systems with defrost timers, a bimetal defrost thermostat would open when the element detects no more ice on the coil, and defrost would terminate.

Joe, Eric, and Bryan also discuss:

• Capillary tubes vs. other fixed-orifice metering devices
• Capillary tube restrictions and R-134A
• Leaky systems
• Vacuum
• Box temperature vs. coil temperature controllers
• Set point and customer expectations
• Safety controls
• Resistance in circuits
• Defrost fan delay and failsafe
• Hoarfrost

Learn more about Refrigeration Technologies HERE.

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Check out The Energy Conservatory at energyconservatory.com.

Learn more about Refrigeration Technologies HERE.

Learn more about Refrigeration Technologies HERE.

James Bowman of Rectorseal returns to the podcast to discuss condensate switch codes and some best practices to comply with the codes.

The humble condensate switch actually has installation standards; although there isn't a "law" about the codes, many areas follow and enforce the contents of the International Mechanical Code (IMC). Some states, including Florida, also adopt elements of the IMC and amend it to create a set of guidelines for the state.

The IMC has widely-enforced code 307.2.3.1, which states that water-level monitoring devices must be installed in the primary drain pan; the device shall shut off the equipment. This code applies to downflow units and all other coils that don't have a secondary drain pan or provisions to install an auxiliary drain pan. The code also states that devices installed in the drain line are not permitted. However, code 307 is actually NOT saying that you can't install a switch in the secondary port at all; there are four different ways to comply with the code without installing a condensate switch in the primary drain pan.

Switches must comply with UL 508. However, there are plenty of non-compliant switches on the market. These may even say that they "conform" to UL 508. Compliant switches will generally not short out when dropped in water, but it's up to us to make sure we're using code-compliant switches.

If you're installing a float switch, be sure to follow the instructions; that's usually the best way to comply with local codes and protect the equipment. As always, make sure you test the switch before you leave the job site.

James and Bryan also discuss:

• Mini-split drain considerations
• Float switches in the primary drain line
• Piping auxiliary floats
• Testing safety switches for heating equipment
• Drain pitch
• Rectorseal condensate switches
• Keeping redundancy in mind
• Condensate switches for RTU and ductless units

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast from our Q&A series, Bryan answers a viewer question and implores you to STOP overthinking in the trade! He also shares a parable and some tips to help stop overthinking, especially if you're just starting out in the trade.

In many cases, the simplest assumption is the right one (this is called Occam's Razor). We can always start with the most obvious or simplest possible answer. We can become mindful of our tools, such as by making sure our seals are intact, and we become masters of the obvious.

Perfecting little things (and micro-tasks) can help you become more familiar with the tools you use and the equipment you work on, and you start to develop a bigger-picture understanding of your craft. Cleaning the equipment and organizing your tool bag goes a long way; you can unlock the ability to zoom out and spot mistakes that you otherwise wouldn't have thought of otherwise.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

Subscribe to our YouTube channel. 

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In HVAC work, we deal with quite a few electrical components. But where does electricity come from? Why do electrons move? In this podcast episode, we talk about differential charges, sine waves, and some voltage measurement basics.

A large chunk of electrical theory is centered on electron movement. We get electrons to move with differentials in charges or energy states. Nature tends towards equilibrium, so electrons will move to restore a state of balance. A battery or transformer does not create energy; they create energy imbalances that cause electron motion to occur. Alternating current (AC) creates a differential by reversing the direction of current several times per second. Transformers and motors use AC power and inductance to drive HVAC systems.

When testing with a voltmeter, you're looking for a difference in charges. So, the probe placement matters. When you have no difference in charges, no electrical work is being done.

Most of the power we use comes from power plants. At these power plants, rotating magnetic fields generate the power we use. Power generated through magnetism creates a sine wave. A sine wave is a variation of a circle; the wave goes up and down in a cyclical pattern. So, you can look at sine waves and determine exactly how legs of power are out of phase with each other. For example, single-phase power comes in and splits at the transformer, creating an opposing sine wave that is 180 degrees out of phase with the power leg (when one wave peaks, the other valleys).

There is also some confusion surrounding "neutral" and "ground." Ground is merely a conductor for safety reasons and has nothing to do with electrical operations; the ground does not generate electron movement. Neutral is NOT the same thing; neutral is a circuit conductor, but we usually connect it to ground.

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In this episode of the HVAC School podcast, host Bryan Orr interviews Tim De Stasio, an experienced HVAC practitioner and consultant. Tim shares his journey in the HVAC industry, from his early days in vocational school to running his own contracting business for 12 years. He now focuses on consulting, design, and contractor training, allowing him to pursue his passion for HVAC while sharing his knowledge with others.

The conversation delves deep into the world of dehumidifiers, exploring their importance in modern HVAC systems, especially in humid climates. Tim emphasizes the need for supplementary dehumidification in many homes, particularly during part-load conditions when air conditioning systems may not effectively control humidity. He explains the process of selecting and sizing dehumidifiers, stressing the importance of considering factors such as peak latent load conditions, actual dehumidifier performance under real-world conditions, and static pressure effects on output capacity.

The discussion also covers the critical role of proper envelope sealing and ductwork in managing humidity. Tim advocates for addressing these issues before installing a dehumidifier, highlighting the importance of blower door testing and fixing any leaks. The podcast concludes with insights on dehumidifier control strategies, the limitations of ERVs in humidity control, and the potential risks associated with uncontrolled outdoor air introduction into HVAC systems.

Key topics covered in the podcast:

• Tim De Stasio's background and transition to HVAC consulting and training
• The importance of supplementary dehumidification in various climates
• Selecting and sizing dehumidifiers based on peak latent load and real-world performance
• The impact of static pressure on dehumidifier output capacity
• The necessity of addressing envelope and ductwork issues before installing dehumidifiers
• Strategies for controlling dehumidifiers in conjunction with AC systems
• Myths about dehumidification, including misconceptions about variable speed equipment and ERVs
• The potential risks of uncontrolled outdoor air introduction and the importance of proper ventilation strategies
• Resources for learning more about dehumidification and HVAC best practices

Contact Tim at timdestasiohvac@gmail.com or follow him on LinkedIn HERE. You can also follow David Schurk on LinkedIn HERE.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

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Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

Learn more about Refrigeration Technologies HERE.

David Holt with NCI returns to the podcast to discuss the evolution of HVAC training; we cover the past, present, and the possible future of training in the industry.

In the past, we had a lot of hands-on training, whether it was one-on-one or in a traditional classroom setting. These learning practices remain beneficial today, especially since many uninformed practices are still prevalent in the industry today (charging to beer-can cold, condemning TXVs without a second thought, etc.).

However, the pandemic has forced us to consider online and remote training in the present. The content has also changed from the past; we are a lot more aware of combustion and airflow nowadays, which are very important topics for safety and efficiency. Those training topics allow us to understand what we’re doing when we take the “vital signs” of the equipment. 

Being better versed in basic and advanced diagnostics will also give us a more holistic understanding of the HVAC equipment as a system, which can help us truly optimize the systems instead of changing parts and making band-aid fixes.

Moving forward, we can expect HVAC training to use virtual reality to help bring traditional hands-on training to the online sphere. We can’t expect a perfect replacement, but we can expect improvements in technology to close the learning gaps that result from online training.

David and Bryan also discuss:

• NCI training during the pandemic
• Components vs. systems
• ASHRAE Standard 221-2020
• Older educational resources and standards
• Occupational safety
• Pricing
• Online classes, podcasts, and other modern training media

Learn more about the National Comfort Institute (NCI)’s training and sign up HERE.

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Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

In this short podcast, Bryan talks about filtration and IAQ, especially as they relate to virus control. He also answers the age-old question: “Can filters capture viruses?”

While it may seem like particle size matters when it comes to filter efficacy, filters are not nets that strain air particles and prevent pollutants from passing through. When we talk about particles, we tend to focus on ones that are 0.3 microns in diameter, which tend to be medium-sized particles. Viruses tend to be among the smallest particles that we aim to control when it comes to IAQ.

Filter media are crisscrossed fibers that catch particles in different ways. Inertial impaction is one means of stopping particles from passing through; the initial impact stops the particles from passing through. Interception happens when particles graze filter fibers and get stuck. Electrostatic attraction relies on energy to attract and catch particles. Diffusion happens when smaller particles move more erratically due to Brownian motion and get caught in the filter media. 

Viruses are among those smaller particles. Smaller particles’ erratic motion makes them more likely to collide with the filter media, so they aren’t necessarily harder to catch. Higher MERV ratings are associated with higher capture efficiencies. HEPA filters surpass the MERV scale and have also been proven to filter viruses out of the air, but we rarely use true HEPA filtration in residential HVAC because they are too restrictive for total system airflow. We can use bypass HEPA filtration to filter the air without creating a massive restriction at the unit. Large filter-back returns with 2” filters can help catch more particles with a greater surface area without tanking the static pressure.

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

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In this podcast episode, Jim Bergmann continues talking about standard air, air density, and mass vs. volume as well as some other methods of "directly" measuring airflow. It gets pretty deep.

Airflow hoods and vane anemometers can give you direct airflow measurements.

You use static pressure probes, not pitot tubes, to measure TESP. When measuring static pressure, you put the negative probe in the return and the positive probe in the supply. Then, you measure the TESP (away from wiring and airflow). However, air pressure fluctuates as that air moves in the duct. Velocity pressure occurs when air moves and creates turbulence. The blower moves air, which has weight. As such, density, volume, and mass are all important as well. As air density changes, the CFM remains constant at a variable mass flow rate.

When it comes to using any tool for measuring airflow, static pressure, etc., all tools are an investment of money and time; you must spend some time learning how to use those tools. You will discover those tools' limitations and must learn how to work with or around those limitations.

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Many technicians use hard or soft copper without thinking about which application is best for which. In this short podcast, Bryan talks about where to use each. He also covers some hanging and strapping strategies.

Residential service technicians typically work with soft copper. Conversely, commercial techs are probably much familiar with the hard variety. Both hard and soft types are good for specific applications.

If you need to work the copper, then the soft type is best for that. You can bend it by hand or with a bender without too much trouble, and it is ideal for flaring and swaging. However, it does not hang well and is not very structurally sound. If you need to hang copper through an attic or light commercial space, then you're really better off with the hard type. The soft kind also doesn't look quite as nice as its hard counterpart when you use it to feed several condensers with a line set.

Hard copper is straight, rigid, and holds up much better than the soft kind when it must be strapped, and it sometimes comes with rubber plugs. Strapping is not a practice that we commonly think about in residential HVAC, but we still need to strap our piping appropriately. We can use Unistrut and clamps to strap our piping correctly. You can bend, swage, and flare hard copper, but you must heat it before you work it; the hard variety can take a lot more abuse than soft copper and is much more durable. You also probably can't transport this type of copper in a van easily, as it can come in very long segments.

Check out Refrigeration Technologies HERE.

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In this podcast episode, Bryan and Eric Mele discuss the diagnosis and prevention of compressor overheating in HVAC and refrigeration.

The main causes of compressor overheating are inadequate cooling back to the compressor, low charge, restrictions, and sometimes even poor suction line insulation. We want to keep the suction temperature low while maintaining appropriate superheat. If the suction line temperature is too high, the compressor can't cool down well enough. Dirty condenser coils, low voltage, weak capacitors, or an inadequate condenser fan can also lead to compressor overheating.

Electrical problems, including too little capacitance, will make a compressor go out on thermal overload. When you have refrigerant problems, the thermal mass will just keep growing; it takes a long time to heat the compressor up, and it will take a long time to cool it down.

In a thermal overload, a bimetallic disk in the compressor will open and break all three legs of power. When a compressor goes out on thermal overload, it will make an open circuit, and you will read infinite ohms. Knowing that the compressor has gone out on thermal overload is just the beginning of compressor overheating diagnosis.

So, to begin diagnosis, you'll want to make sure there's refrigerant in the system. Inspect the unit visually and note anything that seems odd. Then, you'd check your capacitor for electrical problems. You can also feel the compressor to get an idea of the extent of the overheating (try not to burn yourself). You'll also want to monitor the amp draw, condensing temperature, suction pressure, and superheat.

Eric and Bryan also discuss:

• Axial fans
• Condenser fan intermittent failures
• Resetting the compressor
• Cooling down the compressor
• Setting up your meter
• Being out on high pressure
• Wrapping wire to increase ammeter resolution
• High return gas temperature

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan talks about motor speed and other basic electrical topics as they relate to motors in HVAC equipment.

In a typical single-phase PSC-type (induction-driven) motor, the speed is primarily determined by the electrical cycle rate, also known as the hertz. The hertz represents the speed at which the electrical current changes direction (positive to negative) per second; in the USA, that number is typically 60 hertz. Unless we're dealing with ECMs and VFD-driven motors, the motor speed will be partially influenced by the hertz or frequency as determined by the utility company or a generator.

Motor speed is also determined by the number of magnetic poles in the motor. A motor doesn't make a complete revolution per cycle; a cycle only refers to the distance between two poles. The more poles we have, the shorter the distance needs to turn per cycle. A two-pole motor rotates all the way every cycle, resulting in 3600 RPM under no-slip conditions (synchronous speed). A four-pole motor has half the RPM, and an eight-pole motor has 1/4 of the RPM of a two-pole motor.

Speed taps add winding resistance between run and common to create slip and slow the motor. A six-pole motor has 1200 RPM synchronous, but 1075 is the effective speed with slip factored in. Each speed has a different level of winding resistance, which slows the motor as you move from high to low; the lower-speed tap has higher resistance than high-speed taps.

ECMs and VFD-driven systems convert the frequency and don't depend on the electrical frequency from the utility or generator.

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

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Refrigeration Mentor founder Trevor Matthews returns to the HVAC School podcast to talk about personal development and training, including tips for learning in HVAC/R.

When you’re looking at a problem in the field or in training, it pays to take a step back, cool down, and reevaluate your mindset. Trevor recommends thinking about the worst-case scenario and seeing how you can either prevent it or grow from it. It’s good to walk away for a little bit anytime you feel like you’re overanalyzing anything so that you don’t make blunders. 

Trevor has found that reading books is one of the best ways to learn about HVAC/R. HVAC/R professionals can greatly benefit from investing in themselves and setting up their own self-directed training programs. Trainers and mentors can’t be the only ones motivating HVAC/R professionals, holding them accountable, and stimulating their growth.

Many times, our own limiting beliefs of ourselves hold us back, and we need to convince ourselves that we can learn difficult things, even if it isn’t easy. We can also limit our ratio of entertainment to education; focusing more on the latter can greatly benefit your personal development.

Setting educational goals is also difficult when we work long hours and simply don’t have the time or energy to invest in ourselves. The industry needs reform, and reform that raises base rates and prevents an over-reliance on overtime might also attract some new professionals to the field.

Trevor and Bryan also discuss:

• Trevor’s new podcast
• Clearing your head
• Books about doing the hard things first
• Autodidactism and “learning how to learn”
• Subconscious cost-benefit analysis
• The industry’s addiction to overtime
• Helpful books and podcasts for personal development
• Getting rid of “tunnel vision”

Recommended book/podcast list:

• Eat That Frog!: 21 Great Ways to Stop Procrastinating and Get More Done in Less Time by Brian Tracy
• How to Win Friends & Influence People by Dale Carnegie
• QBQ! The Question Behind the Question: Practicing Personal Accountability at Work and in Life by John G. Miller
• Mindset: The New Psychology of Success by Carol S. Dweck
• Grit: The Power of Passion and Perseverance by Angela Duckworth
• Mastery by Robert Greene
• Good to Great: Why Some Companies Make the Leap and Others Don't by Jim Collins
• Built to Last: Successful Habits of Visionary Companies by Jim Collins
• Entreleadership: 20 Years of Practical Business Wisdom from the Trenches by Dave Ramsey
• Culture Code: The Secrets of Highly Successful Groups by Daniel Coyle
• Discipline Without Punishment: The Proven Strategy That Turns Problem Employees Into Superior Performers by Dick Grote
• Atomic Habits: An Easy & Proven Way to Build Good Habits & Break Bad Ones by James Clear
• Rich Dad Poor Dad: What the Rich Teach Their Kids About Money That the Poor and Middle Class Do Not! by Robert T. Kiyosaki
• The Richest Man in Babylon by George S. Clason
• The Big Short: Inside the Doomsday Machine by Michael Lewis
• Antifragile: Things That Gain from Disorder by Nassim Nicholas Taleb
• Think and Grow Rich by Napoleon Hill
• The 5 AM Miracle Podcast
• The Mindvalley Podcast
• Hidden Brain Podcast

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

In today’s short podcast, Bryan explores the dangers of cold tanks during refrigerant recovery.

Whenever you have a recovery tank, you only want to fill it to 80% capacity in the liquid state. The same goes for all sorts of vessels (coils, etc.). 

However, capacity isn’t the only factor to consider for safety. We need to know what our maximum temperature will be. You will be in greater danger of overfilling a tank when it is cold because higher temperatures increase the pressure. High pressure in a closed space may lead to explosions. When you fill a tank to 80% under cold conditions, normal temperature conditions could put you in the danger zone (let alone temperatures above 100°F).

So, it’s better to determine your tank fill based on densities at the MAXIMUM temperatures you will encounter, NOT for the measurements at artificial cooling conditions (such as when you put the tank in ice water during recovery).

In the end, just be careful when you’re recovering into a cold tank or using tanks when it’s cold outside. That will help you avoid hydrostatic pressure buildup and explosions.

Bryan covers:

• The 80% capacity rule for filling vessels with liquid
• Why the 80% capacity rule varies by temperature
• Temperature, pressure, and density
• Hydrostatic pressure
• AHRI’s 77°F guideline
• Ice buckets for recovery
• What to do if a tank vents its refrigerant on you while driving

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Learn more about Refrigeration Technologies HERE.

In this short podcast, Bryan answers a listener-submitted question about duct smoke detector facts and wiring. He focuses on Honeywell duct smoke detectors (namely the D4120W), but there are some general best practices that can be applied to most duct smoke detectors.

The power supply may be 24v or 120v AC or DC and may have multiple inputs. You should not break that constant power source. There are also fan shutdown contacts, which may be normally open (alarm condition) or normally closed (non-alarm condition). Supervisory contacts open to indicate a trouble condition to the panel when something in the circuit isn't working properly (NOT an alarm condition). There is often a resistor at the end of the loop, and the alarm panel recognizes a specific resistance. Alarm initiation contacts close and create a shorted condition when there is an alarm condition (the supervisory contacts open if there is a trouble condition). 

Smoke detectors in the ducts are different from the ones on ceilings; they usually shut down blowers to prevent the distribution of smoke through the ductwork (and possibly exhaust it to the outside). They are required in duct systems designed for more than (or at least) 2000 CFM per NFPA90 and IMC 606.2.1, though those codes conflict. NFPA90 requires installation in the supply duct, but IMC 606.2.1 requires installation in the return; the AHJ may interpret the code either way. (Smoke detectors in systems >15000 CFM must be in both the return and the supply.)

Overall, remember that different detectors are suitable for different velocities. You will want to keep them downstream of bends for at least 18 inches, test them according to the AHJ, and ensure that they are mounted in the right configuration as recommended by the manufacturer.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

Subscribe to our YouTube channel. 

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In this short podcast episode, Bryan Orr discusses the best practice methods for testing run capacitors in the field.

We understand the capacitor to be a voltage storage device. We can benefit from comparing the capacitor to a balloon that inflates and deflates with electrons as the alternating current changes (60 times per second). A capacitor causes a phase shift and allows there to be current on the start winding. So, when a run capacitor fails, you won't have current on the start winding.

The old-fashioned way of testing a run capacitor was to take an ohmmeter and charge/discharge the capacitor. Nowadays, we have capacitor testers, and many multimeters also have capacitance testers. Capacitance is merely a mathematical equation that you use when you compare the amount of voltage to the amount of current entering and leaving.

A good way to test a capacitor on a running system is to test it under load. You take the amperage of the wire feeding the start winding and multiply it by 2652. Then, you divide that product by the incoming voltage across the capacitor to get the capacitance. While this method is probably the most practical, it still has a caveat; some meters may have a hard time getting a proper amp reading on the start winding. So, tool accuracy will also determine your success when testing capacitors under load. To increase accuracy, make sure your wires are isolated from others. Under-load testing may also be unsafe in some cases, such as with a blower capacitor.

Testing with the system off is called bench testing, and it is slightly more accurate but does not represent under-load conditions. It will be more practical than under-load testing if the system is already off or if it is unsafe to test the capacitor under load.

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode of the HVAC School Podcast, Trevor Matthews and Bryan dive deep into the transformative potential of artificial intelligence (AI) in the refrigeration and HVAC industries. They explore how AI is not a new concept in their field, discussing how manufacturers like Copeland, Sporlan, and Danfoss have long incorporated AI-driven tools and repositories of information into their applications. The conversation goes beyond simple technological novelty, positioning AI as a powerful learning and troubleshooting assistant for technicians.

The discussion highlights AI's role as a supportive tool rather than a job replacement. Trevor emphasizes that AI cannot physically perform trade-specific tasks like climbing ladders or brazing pipes, but it can provide invaluable guidance, explain complex procedures, and help technicians quickly access specialized knowledge. Particularly beneficial for less experienced technicians working late-night shifts or challenging service calls, AI can serve as an instant reference point, helping to jog memory and provide step-by-step troubleshooting guidance.

Bryan and Trevor both stress the importance of approaching AI with curiosity and critical thinking. They advise against treating AI-generated information as absolute truth, instead recommending users ask follow-up questions, verify information, and use AI as a conversational learning tool. Trevor is actively developing a specialized AI platform for refrigeration training, working to train the system with industry-specific knowledge and real-world experience to create a more accurate and helpful resource for technicians.

Key Topics Covered:

• AI's current applications in refrigeration and HVAC industries
• How AI can support technician learning and troubleshooting
• Strategies for effectively using AI tools
• The importance of maintaining technical knowledge while using AI
• Trevor's ongoing development of a specialized refrigeration AI training platform
• Practical examples of AI use in technical and non-technical scenarios
• Addressing concerns about AI potentially "dumbing down" the industry

For those interested in participating in Trevor's AI beta test, email info@refrigerationmentor.com with the subject line "Looking to be included in the beta test for the refrigeration training AI." You can also visit the Refrigeration Mentor website at https://refrigerationmentor.com/. 

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

Subscribe to our YouTube channel. 

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android

In this insightful discussion at AHR 2025 in Orlando, Bryan connects with Nikki Krueger from Santa Fe dehumidifiers, exploring the evolution and importance of whole-house dehumidification in modern HVAC systems. Nikki, who has spent 20 years in the indoor air quality industry, shares her journey from a public relations background to becoming deeply involved in the technical and engineering aspects of dehumidification technology. She highlights the groundbreaking work of Ken Gehring, who invented whole-house ventilating dehumidifiers in the mid-1990s and continues to be actively involved in the industry at 84 years old.

The conversation delves into the changing landscape of home construction and its impact on dehumidification needs. As houses become tighter due to building codes and energy efficiency requirements, the relationship between air conditioning and dehumidification has become more complex. They discuss how modern, high-efficiency AC systems often struggle with effective dehumidification due to their focus on temperature control and energy efficiency. This challenge is particularly evident in cases where AC units have higher sensible heat ratios, meaning they're better at changing temperature than removing moisture.

A significant portion of the discussion focuses on the technical aspects of sizing and installing dehumidifiers correctly. Nikki emphasizes the importance of understanding true dehumidifier capacity under different conditions, noting that a unit's performance varies significantly based on temperature and humidity levels. The conversation also covers the evolution of ventilation requirements in modern homes and Santa Fe's response with new products featuring larger fans and eight-inch ventilation ducts to better match dehumidification capacity with ventilation needs.

Key Topics Covered:

• The history and evolution of whole-house dehumidification
• The relationship between modern AC systems and dehumidification challenges
• The importance of proper sizing and installation of dehumidifiers
• How building codes and tighter construction affect moisture control needs
• The role of ventilation in modern dehumidification systems
• The impact of temperature on dehumidifier performance ratings
• Common installation mistakes and best practices
• The significance of dew point versus relative humidity
• The challenges of maintaining specific relative humidity levels in homes
• New developments in dehumidifier technology, including larger ventilation ducts
• The importance of proper data and performance metrics in system design
• Resources for contractors and technicians learning about dehumidification

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android

Trevor Matthews is back and dropping more compressor knowledge on us. This time, he talks about demand cooling and liquid and vapor injection.

In low-temperature applications, the discharge temperature would get very high and lead to oil breakdown and thermal overload, so demand cooling is a means of cooling the compressor. Demand cooling injects saturated refrigerant into the compressor body to cool it down. You're not jamming liquid into the compressor; the refrigerant flashes, which achieves a cooling effect.

A demand cooling system consists of a module, temperature probe, liquid line solenoid valve, and injection valve. On the Discus compressors, the sensor will go in the port in the compressor head. When installing these, it is important to make sure high-quality goes to the valve. It's normal to have some frost at the outlet during operation; look for frost to make sure the demand cooling system is working properly.

Scroll compressors use liquid and vapor injection almost exclusively nowadays. However, there is a difference between liquid and vapor injection for scroll compressors. A liquid injection system helps the compressor avoid high discharge temperatures (and high compression ratios). The vapor injection improves capacity and efficiency.

When troubleshooting demand cooling or liquid/vapor injection systems, you need to keep a few things in mind. For example, you need to make sure you have the right amount of tees when you retrofit a compressor with a vapor injection system. You may also have to repipe the vapor line and add a DTC (discharge temperature control valves).

Trevor and Bryan also discuss:

• What happens when we change refrigerants
• Return gas temperature and mass flow rate
• Compressor head cooling fans
• Motor operation and spinning indicators
• Visual inspection
• Vapor injection vs. mechanical subcooling
• KVE vs. K4E
• Part replacement
• DTC vs. EEV w/ CoreSense diagnostics

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this live episode, we talk about heat pumps, why Bryan likes them, why other people don’t, charging and diagnosing them, and defrost.

Even though heat pumps work best in warmer climates, they can theoretically work as long as the temperature is above absolute zero (-460 degrees F). Viewers across the USA install heat pumps in their markets, even in places with cold winters like Wisconsin. Ideally, the discharge line should be around 100 degrees above the outdoor temperature in heat mode. Although this rule of thumb appears to work in many different climates, it is only really applicable on single-stage equipment.

When charging heat pumps from scratch, check the manufacturer data in heat mode. Airflow for comfort or efficiency is something else to account for when you're commissioning a heat pump; the CFM should be higher if you want the system to be efficient, but the building will be more comfortable if you have a lower CFM per ton. Airflow is especially important to control in heat mode, as small changes can noticeably affect head pressure.

When it comes to defrost, heat pumps typically use a time and temperature strategy. Defrost cycles usually run at a certain temperature for a fixed time period. Heat pump defrost boards usually look a lot more complicated than they really are; when you come across them, stay calm and remember that they're just like any other board.

We also discuss:

• Absolute zero
• Climate zones
• “Vapor line”
• Discharge superheat vs. over ambient
• W calls
• Supplementary heat and dehumidification
• Confirming airflow on a heat pump in heat mode
• Controlling mean radiant temperature (MRT) vs. blowing hot air
• Using in-duct psychrometers and manufacturer charts to assess system performance
• How reversing valves may fail or get stuck
• Thermal imaging applications
• Copeland compressors and mobile app
• Testing defrost boards
• Carrier vs. Trane & Rheem defrost strategies
• Demand defrost
• Suction pressure and compression ratio under frost buildup

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Andy Holt joins the podcast to talk about what it means to be a 24-Hour Technician. We talk about what it means to be HVAC/R technicians AND deal with the human aspects of our lives at the same time.

Service technicians differ from installers in that they do much of their work solitarily. They spend a lot of time by themselves. They’re also on their feet very often and may do emotionally exhausting work, but they can earn a respectable living and accumulate savings for the future. To make our work and the emotional burdens that come with it more manageable, we can try to control how we react—take out head trash.

Most people—but especially technicians—experience anxiety, and worrying about things takes a major toll on us. We also may need to apologize to people who we simply can’t access. Andy goes over some of his best tips for dealing with those sources of worry. The goal is to eliminate negativity—clearing up negative aspects of your life and not being weighed down by individuals who negatively affect your life.

As technicians, we do a lot of work to help other people, and the opportunities are endless for us. Customers may not always understand the value of the work we do, but we can bring positive experiences to them. We can find a lot of fulfillment in our work that way and bring positivity to our own lives.

Andy and Bryan also discuss:

• Replacing negative thoughts with more positive ones
• The power of handshakes and eye contact
• Carrying burdens and being kind
• Apologies and forgiveness
• How to apologize to inaccessible people
• Being a “24-Hour person”
• Using overtime to avoid our lives outside of work
• How to manage anxiety
• Casting a future
• Andy Holt’s Outdoor University

To get in touch with Andy, visit https://toprate.com/ or call (706)-888-2332. You can also email Andy at andy@toprate.com. 

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In this short Q&A podcast episode, Bryan answers Jeremy's question about checking the charge on rooftop units, and he gives some RTU tips.

Rooftop units often come in sets, so you can use a thermal camera to look at all of the RTUs and compare them. A thermal imaging camera may even show you where subcooling begins in the condenser, which can be a useful diagnostic hack. Try to avoid hooking up gauges each time you check the charge on a rooftop; RTUs have a fixed factory charge, and losses from your gauges can add up over time. Your senses will also come in handy; check for odd sights, sounds, and smells.

Checking suction pressure and superheat is less risky and imperfect, but it'll give you some diagnostic data. You can also check discharge temperatures to check for signs of compressor overheating (remember: 225 stay alive). 

Here are some tips for RTUs:

• Get familiar with the service manual and wiring diagrams; these items will help you with the job and help you build on your knowledge of RTUs in general.
• Make sure you have all of your materials at the ready, including extra screws.
• Make sure you have access to the BAS system, if necessary.
• Safety is critical on rooftop units, especially when it comes to ladders, lockout/tagout, and ensuring that you have safe access to the unit (this burden is often on the client). 
• Pay attention to specialized equipment, including ERVs and economizers.
• Be mindful of curb installation, transformer taps, and phase monitoring, as those items may not be set up properly.
• Build up a basic working knowledge of variable frequency drives or VFDs (or know where to find information about them; THIS livestream is a good start),
• Keep systems clean to prevent overheating.
• Prevent oil logging whenever you have to replace a compressor.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your virtual tickets for the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24. 

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Learn more about Refrigeration Technologies HERE.

Rajan Rajendran and Jennifer Butsch from Emerson join the podcast to discuss the Helix and some refrigerant changes that are coming. Jennifer is the Director of Regulatory Affairs, and Rajan is the Global Vice President for Environmental Sustainability and former director of the Emerson Helix.

Lately, there have been more environmental efforts to reduce greenhouse gas emissions, and plenty of large corporations have “net zero” initiatives. Sustainability requires a holistic, systemic approach in our industry; the Helix Innovation Center conducts the research needed for us to handle these sustainability initiatives as effectively and safely as possible.

However, the sustainability initiatives frustrate a lot of technicians. There will likely be multiple refrigerant transitions as our industry progresses. Education and knowledge provided by manufacturers and HVAC organizations will be the key to smooth transitions.

Many of the replacement refrigerants, including R-32 and R-454B, are A2Ls. These mildly flammable refrigerants have different handling, transportation, and charging procedures than what we’re used to. However, we are unlikely to see changes in oils; POE and PVE oil will likely remain dominant in the market.

Eventually, we may see more GWP changes. We would also be prudent to focus on preventing and rectifying equipment leaks. Proper maintenance will help us navigate current and possible future changes.

Rajan, Jennifer, and Bryan also discuss:

• The AIM Act and HFC reduction in 2024
• GWP-limit petitions in HVAC vs. refrigeration
• Refrigerants that manufacturers are embracing
• Refrigerant testing processes
• Natural refrigerants
• The weight of refrigerants vs. the weight of air
• Evaporator coil manufacturing and leakage
• Built-in leak detection
• Refrigerant pricing

To learn more about these coming refrigerant changes, check out the AHRI Safe Refrigerant Transition Task Force’s resources HERE or Emerson’s E360 Platform HERE.

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Check out our handy calculators HERE.

Ryan Gorman comes on the podcast to discuss the differences between a college education and early career opportunities in the skilled trades.

Many parents feel pressured to send their children to college and encourage them to get a four-year degree. Despite what society may lead us to believe, there is no shame in thinking that college may not be suitable for you or your child; the skilled trades have many opportunities for people to learn throughout their lives and make a good living.

In many cases, parents may see college as a ticket to the starting line. Unfortunately, college tuition has skyrocketed over the years, and a good ROI is not guaranteed. Instead, a career in the skilled trades can allow a person to develop hard skills and land a well-paying job at a young age. As the skills gap widens, young people who learn skills make themselves attractive to employers and increase their earning potential.

Children and teenagers who want to become engineers may actually prefer a trades career where they get to work with their hands. The path to the trades is less expensive than getting a four-year degree and may prove more fulfilling in the long run. Internships, small businesses, and trades careers are viable paths for young people; we don’t present these possibilities at a young age, but they are worth considering for people who may not benefit from college.

Ryan and Bryan also discuss:

• The arbitrary structure of college programs
• Parents wanting better for their children
• Overvaluing the 4-year degree
• Networking
• The skills gap
• Craftsperson vs. technician
• Feeling "stuck"
• Attending college at an older age
• Lifelong learning
• Universal skills vs. specialization
• Suggested resources for people who feel "stuck"

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

In this podcast, Bryan Orr interviews Jesse Stewart from NAVAC about A2L refrigerants and compatible tools and safety procedures.

They discuss how NAVAC has a full line of A2L-compatible tools for evacuation and recovery, including the new NR7 and upgraded models of the NRDDF and NRDD. Jesse explains key features that make tools A2L compatible, like DC motors, sparkless designs, insulated electrical terminations, soft power switches, and fans. He notes that NAVAC has been designing tools this way in preparation for wider A2L adoption.

The conversation covers some evolving questions around A2L systems, like requirements for strike plates to protect line sets and whether existing line sets can still be used. They agree that ongoing questions need to be directed to organizations like ASHRAE to get definitive guidance. Overall, Jesse emphasizes that best practices are now required, not just recommended, when working with A2Ls. He details several examples, like nitrogen purging while brazing, the "10-foot rule" for checking potential ignition sources, and proper confined space protocols.

Topics covered:

• NAVAC's line of A2L-compatible tools
• Key safety features for A2L tools
• Evolving regulations and best practices around A2L systems
• Using nitrogen while brazing
• The "10 foot rule" before A2L installations
• Working in confined spaces with A2Ls
• Adapting outdated practices to meet new safety needs

Explore NAVAC's A2L-compatible tools at https://navacglobal.com/a2l-compatible-tools/ or general products at https://navacglobal.com/. You can also ask the experts for help by emailing training@navacglobal.com.   

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”

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Duct and air handler (unit) sweating is a common issue in humid climates. Bryan talks about what causes it and what to do about it.

Many people try to keep their ducts and equipment either very cool or very warm to prevent sweating. Despite the good intentions, neither of those methods is great for sweat prevention. If a ceiling grille is sweating, people try to insulate the top of the boot to stop the sweating. The real reason why the grille continues to sweat is that those sweating areas have hit the dew point.

If anything reaches the dew point or lower, you WILL see condensation. Another potential cause is that air with a higher dew point is going into the lower-dew-point space. In the latter case, sealing the ducts and cracks near the boot should help that higher-dew-point air from infiltrating; insulation does very little to address leakage, so air sealing is the real solution. Attics often have air with a higher dew point than the conditioned space.

Equipment sizing is also important. Oversized equipment leads to shorter run times, meaning that the evaporator coil can't get cold enough to remove moisture. When you have a low latent capacity, you won't have proper moisture removal in the home.

We will almost surely encounter sweating when we have air handlers and ducts in unconditioned spaces. To address duct and unit sweating, some technicians increase the air velocity to prevent ducts from sweating, as the higher temperature should prevent the duct jacket from being below the dew point. However, as with oversized equipment, excessive airflow will negatively impact the latent capacity. So, you will have less moisture removal. The best solution is to decrease the attic dew point or increase duct insulation. Reheat solutions are also worth considering on some systems.

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bryan and Jesse talk in detail about ductless applications we commonly see, best system placement, drains, and much more.

Ductless systems are unique, and their compact nature makes them a good choice for several small, controlled applications. These applications are in climate-controlled garages, lanais (sunrooms), and master bedrooms. In Florida, lanais are the primary application for ductless units, especially due to codes that regulate HVAC systems in lanais.

When installing a ductless unit, Jesse looks for aesthetics and reliability. Since ductless units are visible, making them look good inside the home is a concern that you don't typically worry about on split systems. When it comes to the drain line, Jesse likes using gravity drains on exterior walls. Many callbacks deal with drainage issues, so drains can reduce ductless units' reliability. Condensate pumps also occasionally have issues, so Jesse puts the pump in a way where all connection points are below the ceiling to avoid ceiling damage. However, float switches and overflow devices may also be required by code and may help.

Successful system commissioning starts with the mindset. A good commissioning organization broadens its vision; instead of focusing on the appliance, techs and installers focus on the system. Commissioning early on saves time later; you can focus on installs and maintenance instead of callbacks, and your organization can make more money as a result.

When installing and testing new piping, make sure you insulate the tubing properly and keep the lines CLOSED OFF to the atmosphere. Measuring the line set is also critical for weighing the charge properly, as long lines have special considerations.

When doing the decay test, use a quality vacuum rig and try to keep the micron gauge as far away from the pump as possible. Cleaning line sets also helps your vacuum results by getting rid of oil and moisture within the lines.

Flowing nitrogen while brazing and sweeping with nitrogen are two other important installation/commissioning practices. They may seem idealistic, but it’s easy to adopt these practices widely and reduce problematic scale buildup.

Methods for setting airflow have changed over time. Nowadays, the best practice is to take a volumetric flow measurement (such as with a TrueFlow grid).

Jim and Bryan also discuss:

• Preventing callbacks and warranty returns
• Evacuation and dehydration
• Factory practices
• One-hose evacuation with large hoses
• Flushing the line sets with pigs
• Nitrogen flow regulators
• “Airflow before charging” and metering devices
• Special considerations for MicroChannel coils

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Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

In this short podcast episode, Bryan goes over the basic gas furnace sequence of operations. There are a few variations, but the sequence of operations tends to stay consistent across most furnace types.

First, a W call from the thermostat calls for heat. The circuit board will then assess the safeties to see if it can bring on the heat without causing flame rollout or other dangerous conditions. If the safety switches are all closed, then the furnace can bring on the heat. However, in some cases, the induced draft motor may come on first in some 80% furnaces. There needs to be a small negative pressure in the induced draft motor housing. To confirm that we have that pressure, a pressure switch will close under the right conditions.

Then, ignition begins. In most cases, we use intermittent-spark ignition (ISI) or hot-surface ignition (HSI). It takes some time for these methods to light the pilot, which then lights the main burner. After that, the gas valve opens to fuel the burner. On an ISI system, that’s about it until the blower comes on. However, once the main burner opens on an HSI system, a flame sensing rod can verify if you have a flame on that burner. There is a blower delay that prevents the blower from coming on and blowing a bunch of air that hasn’t yet been heated.

After that, the blower delay ends, and the blower comes on. Then, the furnace shuts off when the W call ends. Then the blower continues running for a little bit before turning off.

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Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

James Bowman returns to the podcast to talk about analog vs. digital manifolds. He also explains why both of them may still have a place in the industry.

Pricing is a key difference between analog and digital manifolds. Analog manifolds tend to be less expensive and will suffice just fine for techs who don't require readings with a lot of detail. While digital manifolds will be more expensive, they can also give you more precise, detailed readings. So, digital manifolds have a slight leg-up in terms of resolution as well; these manifolds are generally better for critical-charge or MicroChannel systems.

Learning to take readings on analog manifolds early on may be advantageous for young or inexperienced techs. You learn more about superheat, subcooling, and interpreting readings when you start off with an analog gauge manifold. The process of taking readings on digital gauges is automated; therefore, digital gauges are less effective as learning tools.

If you want to recover refrigerant, you might be better off using an analog manifold. These are less expensive and may be better equipped to deal with the nasty contaminants inside a system. Digital manifolds are more expensive and should not be exposed to contamination if you want them to last a long time.

We often use accuracy and resolution interchangeably, but accuracy refers to the correctness of a reading. Resolution refers to the scale of the measurement. Digital manifolds usually have advantages in both of these areas, as they can usually take finer readings.

James and Bryan also discuss:

• Critically charged systems
• Charging and recovery
• Hoses
• Ductless systems
• Technological and practical changes in our industry's future
• Using probes to take readings
• Single-port manifolds
• Applications where accuracy is most important
• Causes of inaccuracy
• Calibrating probes and other tools

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this second part of the podcast, Jim Bergmann wraps up the steps to check a system charge without connecting a gauge manifold.

You can check the charge without gauges if you use the following process (and know your DTD, CTOA, etc.):

1. Take the dry-bulb temperature. (Let's say it's 70°F in this example.)
2. Subtract the DTD (35°F).
3. Add target superheat (10°F).
4. Check the suction line. It should be 45°F in this example. If your probe senses a temperature that is NOT within 5°F of the temperature you calculated, check the filter, evaporator coil, etc., for dirt.
5. If the system is not dirty, check the charge with gauges.

For a more extensive look at the process in writing, check out THIS article.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, Neil Comparetto from Comparetto Comfort Solutions joins Bryan and Kaleb to discuss some duct installation best practices he has learned. You might be able to take away some of his duct installation tips and apply them in the field.

Neil used to focus a lot on making the ducts look good, but nowadays, he focuses a lot more on performance; the work of art is in the data, not the beauty of the building materials. The quality of the seal on the duct is more important than the duct's appearance. Neil focuses a lot on leakage, and he says it all starts by committing to low-leakage connections in your mindset. He does as much sealing as he can before hanging the ducts.

Flex duct is one of Neil's favorite materials even despite its poor durability. Flex duct is quiet, well-insulated, pretty cheap, normally leak-free, and quick to install. Of course, you must install it in straight lines and pull it tight for best results, but its performance is pretty close to that of normal sheet metal.

It can be difficult to separate the install from the design, so some design features are beyond the installer's control. However, if possible, it's best to keep the duct system as small as possible. Shorter ducts reduce the likelihood of leakage and the area available for thermal transfer, especially in unconditioned spaces.

Neil, Kaleb, and Bryan also discuss:

• Design and preparation before installation
• Squeegee, tape, insulation, and mastic
• Brands that Neil likes
• Splicing flex duct
• Finding friction rate and balancing
• Downsizing equipment
• Building codes and inspections
• Balancing supply and return
• Return grille placement on homes with few large returns
• Getting feedback
• Equivalent lengths of straight vs. 90 boots
• Duct vs. register velocity
• Takeoffs
• Dos and Don'ts of duct installation
• Filters

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan goes over a few tubing insulation tips. Tubing insulation is also commonly known as Aeroflex, Armaflex, and Thermaflex—all brand names for black copper line set insulation.

We typically have to insulate just the suction line in typical residential split HVAC systems, but you'll typically have to insulate both lines in ductless/VRV/VRF or refrigeration applications. The insulation should be on the tubing before brazing, gluing the ends together (only using a specialty tubing insulation adhesive, NOT duct tape!). Since these adhesives are types of contact cement, you will need to apply a thin coating on each side of the joint and wait for a few minutes before pushing the ends together. Some forms of tubing insulation are split and have an adhesive flap instead.

Then, you'll want to hold the insulation back with a clamp about 8-10" away from the area where you're brazing to protect it from heat damage. When you finish brazing, you'll want to put the insulation back and make sure all necessary areas are covered. In cases where it's practical, especially in residential HVAC, pulling the insulation over the 90s and P-traps may be the best bet due to its smaller margins for error. However, mitered fittings may be required in larger systems.

To assemble mitered fittings, use either a miter box or the template on the tubing insulation box. It's a good idea to use the disconnected tubing and make a mitered fitting on the bench as a template before making more—the tails can be a little long. Do NOT use the saw that comes with the miter kit—you will be fine with a very sharp knife that makes a smooth edge (and be safe!).

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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Trevor Matthews, the founder of Refrigeration Mentor, returns to the podcast to talk about why CO2 matters in commercial refrigeration and even HVAC applications.

CO2 (R-744) has entered the residential HVAC sphere in some places around the world, though it hasn’t come to the North American markets yet. CO2 is one of the most eco-friendly refrigerants on the market, with a GWP of 1, and it’s very good at moving heat. However, CO2 has some challenges, including its low critical point and higher pressures.  

CO2 comes with some safety concerns, and its systems have a complicated infrastructure. Since CO2 can exist as a liquid, vapor, or solid under operating conditions, you could end up with dry ice in the system. These issues require skilled, attentive technicians.

As the industry moves to natural refrigerants like CO2 and hydrocarbons, we need to stop the race to the bottom. Technicians need to learn how to take their time and do the job right when they work on CO2 equipment so that they can be safe and save energy. 

The future of troubleshooting will eventually lie in electronic controls that take measurements constantly. Technicians won’t lose their necessity with these changes, but it will be easier for them to respond to those measurements directly without connecting gauges. Technicians will also be able to access performance logs, which can help diagnose long-term problems.

Trevor and Bryan also discuss:

• Trevor’s history working with CO2
• Refrigerant regulations
• Transcritical CO2 and climate
• The skills and proficiency of young technicians
• Dry ice in CO2 systems
• Pressure transducers and pressure release valves
• Manufacturer support and quality control
• Data logging and electronic controls in commercial refrigeration
• Trevor’s recommended resources for CO2 education and training

Check out Trevor’s mentorship and training initiative at refrigerationmentor.com. 

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Check out our handy calculators HERE.

This podcast is a class taught by Bryan: Things to Keep Out of the System. He covers some installation best practices along the way to keep contaminants and non-condensable gases out of the system.

We want to keep air, water, dirt, copper shavings, solvents, and nitrogen out of an operating system. All we want in an operating system is the appropriate oil and refrigerant for the system. Unfortunately, the POE and PVE oil we mostly use in residential systems nowadays are very hygroscopic; they attract water, and POE mixes with water to form acid, another thing we want to keep out of the system.

We can pull most of the moisture out of the system by pulling a deep vacuum and following the best practices for a fast and deep evacuation. However, we can also reduce the probability of moisture getting into the system in the first place by NOT working on copper while it's raining outside, sealing the copper tubing adequately when routing it underground or in a chase (a common installation practice in Florida), and insulating it properly.

Dirt can easily get into the system when we're modifying piping, especially when adding fittings or reaming, but we can use nitrogen or line set cleaners to flush it out. Purging the lines and flowing nitrogen while brazing also help keep air and water vapor out of the copper lines. When deburring, try to avoid letting the burr or copper shavings from falling into the tubing.

Bryan also covers:

• Drawbacks to running copper underground
• Oil return and miscibility with refrigerant
• Flowing nitrogen without a regulator
• Leak detection and nitrogen pressure testing
• Why we should ream or deburr copper to prevent leaks
• Being able to trust your equipment

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

In this episode, we cover some common misconceptions about run capacitors, some easy ways to test them, and some tips on working with them.

A run capacitor is a power storage device; it contains oil to dissipate heat and some thin metal plates wrapped in a spiral. Capacitors also contain plastic insulation between the metal plates to keep the power separate; electrons should NOT cross the insulation, and there should be a charge difference between the plates. Current also does NOT flow through the capacitor; capacitors merely store and discharge power.

Capacitors also do NOT boost voltage. You may notice higher voltage between terminals, but the capacitor is not involved in that voltage boost. You see that voltage increase because of the inductive motor's back EMF. Back EMF only occurs on systems with a running motor.

On a single-phase PSC application, the run winding is the primary, and the start winding is the secondary. A run capacitor that is too large will draw more current on the start winding. You may see a slight drop in overall amperage on the common wire, but large capacitors increase the current on the secondary winding. The start winding is not designed to carry excess current.

Connecting capacitors in series REDUCES capacitance. Therefore, most of the time, we connect capacitors in parallel. Many electrical circuits nowadays are connected in parallel (compare to Christmas lights, which are connected in series).

Bryan also covers:

• Capacitor basics (terminals, microfarads, etc.)
• "Common" confusion
• Capacitance and current relationship
• Start capacitors and potential relays
• Hard start kits
• PTCR products
• Series vs. parallel capacitors
• Testing capacitors (in the circuit, under load, with a capacitor tester, etc.)
• Calculating capacitance and evaluating capacitance ratings

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

This episode focuses on understanding and effectively utilizing various refrigeration system charts and measurements for troubleshooting and diagnostics. Joey Henderson, an HVAC veteran and trainer, shares his wealth of knowledge and experience on this topic.

Joey starts by discussing the challenges he faced early in his career when trying to make sense of the confusing charts with arrows indicating high, low, high head, low head, etc. He emphasizes the importance of knowing the "supposed to be" values before attempting any measurements or referencing charts. Without this baseline understanding, the measurements become meaningless.

He then delves into specific measurements like subcooling, superheat, evaporator temperature/suction saturation, condenser split, and compressor amperage. For each measurement, Joey explains the ideal range, how to interpret deviations, and how different factors like humidity, airflow, and refrigerant type can affect these values. He also highlights the differences in approaches for fixed metering devices versus TXV/EEV systems.

Topics covered in the podcast:

• Understanding refrigeration system charts and their limitations
• Importance of knowing "supposed to be" values for meaningful diagnostics
• Measuring and interpreting subcooling
• Measuring and interpreting superheat
• Determining evaporator temperature/suction saturation
• Calculating and understanding condenser split
• Evaluating compressor amperage
• Differences in charging fixed metering devices vs. TXV/EEV systems
• Impact of humidity, airflow, and refrigerant type on measurements
• Using psychrometers and measuring wet bulb temperatures accurately
• Calculating and interpreting Delta T (wet bulb/dry bulb split)
• Resources like the Efficient Comfort website and Dick Wirz's RefTech app

Check out some of the resources discussed at https://efficientcomfort.net/.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

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Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In this short podcast episode, Bryan dives into soft start & solar technology, which often work together. He also talks about how we can install ductless systems in homes that rely on solar power.

Soft starts are NOT hard starts. Hard starts add more current to the start (auxiliary) winding, which creates a stronger phase shift. Instead, soft starts control the current on the start and run windings and provide just enough of a phase shift to ramp up the motor slowly; it provides a regulated power supply, which means that a slow startup doesn't necessarily cause overheating because there is no locked rotor condition.

We can use soft starts on two-stage compressors but need to make sure the compressor goes up to high speed during the starting sequence. Soft starts "learn" the compressor's cycles, so we need to make sure they are trained to reach the high stage, not the low stage. In systems with multiple compressors, we need to have a separate soft start for each compressor. We don't need to use soft starts on inverter-driven or variable frequency drive (VFD) systems.

Soft starts also make sense in systems that rely on solar technology. Solar technology may be on-grid (where we sell back energy during peak times) or off-grid (where energy is banked). Ductless systems can work with solar energy, but they must be connected to the grid or the bank. Banked solar energy doesn't need to be rectified in the same way that AC power from the electrical company does, which may be advantageous for ductless systems that rely on DC-driven technology.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

Subscribe to our YouTube channel. 

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In this unique episode of the HVAC School podcast, Bryan interviews Donovan Ryckis, CEO of Ethos Benefits, diving deep into the complex world of healthcare financing and employee benefits. Ryckis shares his journey from financial advising to becoming a healthcare benefits consultant, driven by a mission to expose and transform the inherently problematic healthcare system.

The conversation reveals the stark inefficiencies in traditional healthcare models, where insurance companies and healthcare providers often prioritize profit over patient care. Ryckis explains how most employers have been led to believe they cannot control healthcare costs, accepting annual increases as inevitable. By applying a fiduciary approach—similar to financial advising—Ethos Benefits helps companies like Kalos dramatically reduce healthcare expenses while maintaining or improving employee care.

A key highlight of the discussion is the innovative strategies Ethos implements, such as negotiating directly with healthcare providers, exposing pharmacy benefit manager markup, and implementing direct primary care. These approaches not only reduce costs but also provide employees with better, more personalized healthcare experiences. The podcast demonstrates that by taking a transparent, data-driven approach, companies can create win-win healthcare solutions that benefit both the organization and its employees.

Key Topics Covered:

• Healthcare financing vs. traditional insurance models
• Pharmacy benefit manager markup and hidden costs
• Negotiating medical claims and reducing excessive billing
• Direct primary care and its benefits
• Strategies for controlling healthcare expenses
• Importance of transparency in healthcare pricing
• The documentary "It's Not Personal, It's Just Healthcare"
• Challenges in the current healthcare system
• Empowering employees through better healthcare options

Learn more about Ethos Benefits at https://ethosbenefits.com/ and the Ethos Effect Podcast at https://www.ethoseffectpodcast.com/.  

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

Subscribe to our YouTube channel. 

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

Learn more about Refrigeration Technologies HERE.

In today’s podcast, Bryan and some Kalos employees discuss how to deal with difficult bosses and coworkers in HVAC/R work.

Whether your coworkers have anger issues, are careless, or are miserable people, you don’t want that negativity to affect your job satisfaction. Addressing the behavior may likely help, but you don’t want to attack the other person. The key to dealing with difficult coworkers is to communicate boundaries respectfully with the goal of improving the work environment. Boundaries are also important when dealing with sarcastic people or those who make inappropriate remarks.

Any work environment with lots of people is bound to have cliques and tribes. You’re best off not getting involved in any of that drama; the best thing you can do is be kind whenever you have the opportunity. Nepotism may also fall under tribal behaviors, and it may cause you to rethink your future with a company.

On the leadership side, micromanagers can be frustrating—doubly so if your boss also happens to be condescending. If you have micromanager tendencies, try setting clear objectives and give your technicians room to develop. (If you’re on the receiving end, talk to your boss about bigger-picture objectives to cut down on micromanagement.)

Learning is all part of working in the HVAC/R field, but you may encounter friction with bosses who won’t invest in learning or coworkers who refuse to learn new things. Try to have productive conversations with these people. If you’re talking to a boss who doesn’t invest in training, try to communicate your professional and educational needs. If you have a stubborn coworker or helper who doesn’t want to learn, try to help them understand the new material by using similes and metaphors.

We also discuss:

• Distractions
• Sarcasm and rudeness
• Egomaniacs
• Inappropriate exaggeration
• Dishonesty
• Overreaction

Check out information on the 2022 HVACR Training Symposium HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Learn more about Refrigeration Technologies HERE.

In this episode of the podcast, Jeremy Arling from the EPA comes on and answers some common questions about the new rule changes that affect recovery, leak repair, recordkeeping, and evacuation on HVAC and refrigeration systems.

EPA 608 rules regulate the actions that technicians must take when it comes to refrigerants and the atmosphere, such as venting, recovery, and evacuation. It has always been illegal to vent HFCs, including R-410A. The changes to EPA 608 attempt to treat all refrigerants equally; R-410A would be on equal footing with HCFC R-22, for example. EPA 608 also clarifies the actions that require certification, including the purchase of ozone-depleting substances.

It is not illegal to recharge CFC or HCFC refrigerants. However, the availability of HCFC refrigerants will dwindle over time; systems will need to be charged with reclaimed refrigerants, not new R-22.

EPA 608 will also crack down on recordkeeping for recovery and reclamation. The technician does NOT have to keep the records; it is the responsibility of the company. However, the technician should keep track of the recoveries they do and provide those records to their companies.

When recharging leaking systems with over 50 lbs of refrigerant, technicians should know that HCFC-reliant appliances must be repaired, retrofitted, or retired within specific timeframes. There is no minimum time frame between the leak repair and verification testing; however, the EPA recommends testing within 10 days of the repair.

The EPA has approved the use and recovery of flammable refrigerants for a handful of industrial applications. Most of these also receive exemptions from the venting prohibition.

Resources

You can find the complete rule update HERE. You can also find Jeremy's presentation slides HERE and a quick sheet for technicians HERE.

If you want an app to help you keep a record of recovered refrigerant, I would suggest looking at the R-Log app HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Have you ever heard a compressor that keeps changing in sound as it runs? Trevor with Emerson tells us more about what that is all about and how the digital compressor operates.

In this short podcast episode, Bryan talks about EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratio) and how to calculate EER in the field.

EER and SEER are ratings that we often see on equipment (as are SEER2 and EER2) based on a ratio of an output to an input. Whereas coefficient of performance (COP) is a direct ratio of watts out to watts in, EER and SEER account for BTUs and watts. EER and SEER indicate the cooling capacity (in BTUs) we get from the watts we put in.

The ratio changes based on field conditions, and EER2 and SEER2 have more realistic test conditions than EER and SEER (the static pressure for systems rated below 65,000 BTUs per hour was 0.1"wc for EER and SEER, and it is now 0.5"wc for EER2 and SEER2, which is much closer to average field conditions).

To determine EER, you have to figure out BTU production and stack it against your wattage. You'll need to know your delta enthalpy (delta H), multiply it by the CFM, and then multiply the product of those by 4.5 to get your BTU output. A calculator on apps like measureQuick can help you find out your delta H, but you'll need a proper wet-bulb temperature before you can do that. You can determine CFM with a TrueFlow grid or manufacturer's blower charts.

Finding watts can be a challenge with ECMs and inverter-driven systems; it's not as simple as volts x amps, and you will need a meter that can measure power factor and take readings from the condenser fan, compressor, and blower motor. That wattage becomes the number you divide into BTUs to get the EER. SEER is averaged over a season, HSPF is for heating instead of cooling, and you can convert the BTUs to watts (by multiplying by 3.41) and determine the ratio of watts out to watts in.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android

This is the episode for you if you've ever asked, "What the flux?" In this short podcast, Bryan explains the basics of flux in soldering and brazing, as well as magnetism.

Flux means "flow." In HVAC, "flux" may have two meanings. It may refer to the substance that helps the molten alloy flow and bond to base metals more effectively when you're soldering or brazing. However, flux may also refer to magnetic flux, which is the lines of force that emanate from a magnet; this concept is important in inductive loads like transformers.

In soldering, brazing, and welding, flux is a powder-paste or liquid that you apply to the base metal. You usually apply it directly to the male side of the base metal, or it may be embedded in the brazing alloy. Flux prevents oxides (like rust or the black flakes, cupric oxide) from forming on the surface you're brazing, which commonly happens at higher temperatures. Flux helps you create a proper bond, but it doesn't eliminate the need to clean the base metal before brazing.

You typically don't need flux when you use silver-phosphorus or phosphorus-copper brazing rods for copper-to-copper brazing; the phosphorus acts as a fluxing agent, and using flux may increase the risk of contamination. It's also important to remove the flux from the metal after brazing because it may cause pitting; you may use a brush and/or a wet rag.

Flux is useful when you use rods with high silver content or when you have other base metals; the appropriate flux will depend on the base metal, especially if you're soldering aluminum.

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Learn more about Refrigeration Technologies HERE.

This podcast brought together several women working in the HVAC industry to discuss their experiences and offer advice. The conversation focused on the positives of working in HVAC as a woman, the importance of community, and the resources available.

The women talked extensively about how welcoming and supportive the HVAC community, and particularly HVAC men, have been towards them. Several got into the industry because of their husbands' work. They agreed the perception that it's difficult for women to break into HVAC does not match their largely positive realities. The biggest challenges they identified related more to things like clothing and bathroom options rather than discrimination or harassment.

Advice offered for companies looking to hire more women focused not on targeting women specifically, which could cause resentment, but on ensuring good benefits, upholding anti-discrimination standards, and facilitating connections with other women in the industry. Several mentioned the value of groups like Women in HVAC and the Society of Women Engineers for networking and support. Attending conferences to connect with the HVAC community was also repeatedly recommended.

Overall, the positive tone revealed that with the right connections, women can thrive in HVAC careers. All expressed passion for their work and eagerness to encourage more women to explore the industry.

Topics covered:

• Getting into HVAC
• Challenges for women in HVAC
• Advice for attracting/supporting women
• Importance of community
• Groups like Women in HVAC
• Conferences/events

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”

Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 

Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).

In today's short podcast episode, Bryan covers the basics of refrigerant oil in HVAC/R systems. He also discusses what technicians can do to maintain oil systems.

Oil lubricates the moving parts of the compressor. So, oil moves with the refrigerant and lubricates the parts as the refrigerant moves through the compressor. Unfortunately, oil can migrate to other parts of the circuit when it's not supposed to.

Flooding occurs when liquid refrigerant enters the compressor crankcase, and slugging occurs when liquid gets into the compressor head. When either of those happens, they can eject oil from the system. When a system has insufficient oil, the compressor's moving parts can heat up and wear out quickly. We can use an array of preventative strategies to keep oil in the system and reduce the risk of compressor damage.

We want to keep our discharge lines below 225 degrees to prevent oil (or lubricant) breakdown. To prevent the compressor from overheating, we want to look at mass flow rates and compression ratios. We should also make cleanliness a priority, as dirty components can increase the compression ratio.

Oil has evolved with refrigerants. We largely used mineral oil with HCFCs like R-22, but we have begun using POE oil with HFC refrigerants like R-410a. Newer HFCs are generally NOT miscible with mineral oil, but we must be careful with POE and PVE refrigerants because they are hygroscopic. These oils break down via hydrolysis when they react with moisture, and they become acidic. So, we need to keep POE and PVE systems dry to prevent damage.

Bryan also covers:

• Hard shut off TXVs
• Pump down cycles
• Oil return
• Viscosity
• Oil velocity and pipe design
• Miscibility
• AB oil

Check out our oil article HERE.

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan talks about TXVs and their impacts on energy efficiency ratings (EER and SEER).

EER (Energy Efficiency Ratio) is calculated based on fixed conditions (an outdoor temperature of 95 degrees Fahrenheit and an inside temperature of 80 degrees with 50% RH). EER is a ratio of cooling-only capacity in BTUs per hour to the total electrical input in watts. SEER (Seasonal Energy Efficiency Ratio) is the ratio of an HVAC system's cooling output during a typical cooling season to the seasonal electrical input in watts.

Both energy efficiency ratios use non-proportional units (BTUs to watts), but SEER is supposed to account for a wide set of conditions (even though the climates of regional markets can vary quite wildly). EER2 and SEER2 are new standards based on updated equipment testing protocols with more realistic static pressures.

TXVs and EEVs can modulate to control the amount of refrigerant going into the evaporator coil. TXVs maintain a set superheat at the evaporator coil outlet, which it detects with a sensing bulb mounted to the suction line. These sorts of modulating metering devices can boost system efficiency by adjusting the amount of refrigerant it feeds into the evaporator coil. Underfeeding can lead to inefficiency, and overfeeding can cause system damage.

Non-bleed TXVs shut tight once the compressor shuts off, which prevents refrigerant migration during the off cycle and pressure equalization, thus protecting the compressor and reducing the cyclic degradation coefficient. The compressor may have to start a little bit harder, but the effects of the hard shutoff can improve the SEER rating by about 0.5. TXV systems are, overall, more efficient than systems fixed-orifice metering devices.

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

In today's podcast episode, Lee Andrews with Andrews Filters talks about the complicated and important topic of air filters and filtration. He also explains why they should matter to you and your customers. As indoor air quality (IAQ) becomes more important in HVAC work, air filters will become even more important than they already are.

We classify air filters by MERV ratings. MERV ratings describe the ability of filters to capture finer particles; a MERV 11 filter will catch a lot more particles than a MERV 6 filter. Most air particulates are an average of 0.4 microns large, but most air filters only catch 5-15% of those particulates. The filter industry aims to catch smaller and smaller particulates to improve indoor air quality, protect equipment, and keep consumers healthier.

However, MERV is not a comprehensive value for efficiency. The actual filter media is also important for a filter's efficiency. Higher-quality, finer fibers will have a higher probability of catching smaller particulates. Having a greater surface area (more pleats) also increases performance. The media has a small charge, which helps a filter collect particles. Humidity, particulate insulation (dirtiness), and alcoholic pollutants (such as diesel) can discharge a filter and reduce efficiency.

Many people use MERV 8 filters, but very few understand the difference between MERV 8 and MERV 8A filters. The addendum of the MERV test (A) uses an alcohol-type product to remove the charge. So, MERV-tested filters without the addendum test can actually perform at a lower-rated level. For example, a MERV 8 filter could perform more like a MERV 5-6 filter.

Bryan and Lee also discuss:

• Electrostatic charge and airflow
• MERV 8 vs. MERV 8A
• Loading and unloading
• Board materials
• Filter design and sizing
• Talking to customers about filters
• Energy savings

Check out Andrews Filter's website at andrewsfilter.com.

Check out Refrigeration Technologies' chemical products HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan and Bert dive deep into the world of low voltage wiring in HVAC systems. They discuss common mistakes, best practices, and troubleshooting techniques that technicians and contractors should be aware of when dealing with control wiring.

The conversation begins with a focus on mechanical issues, such as running wires in places where they can be damaged and poor splicing techniques. Bryan and Bert emphasize the importance of proper wire stripping, both for the outer jacket of control cables and individual conductors. They share tips on how to avoid damaging wires during installation and stress the significance of planning wire placement, especially behind thermostats.

The discussion then shifts to common miswiring issues, including incorrect terminal connections and misunderstandings about system configurations. They explore the challenges of wiring heat pumps, straight cool systems, and gas furnaces, highlighting the importance of understanding how different thermostats and equipment interact. The hosts also delve into the complexities of dehumidification control wiring and the need to comprehend how various controllers operate.

Bryan and Bert also address communicating systems and offer advice on preventing communication issues. They stress the importance of running new control wiring, considering shielded cable for long runs, and being meticulous about connections. 

Topics covered in the podcast:

• Proper wire stripping techniques for control cables
• Common miswiring issues in HVAC systems
• Thermostat wiring and configuration challenges
• Dehumidification control wiring complexities
• Heat pump vs. straight cool/gas furnace wiring differences
• Communicating systems and preventing communication issues
• Using shielded cable for long control wire runs
• Troubleshooting intermittent low voltage problems
• The importance of reading manuals and understanding system configurations
• Tips for managing wires behind thermostats and in control panels
• Using megameters for testing control wires
• Encouragement for technicians dealing with low voltage issues

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.  

Subscribe to our YouTube channel. 

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

Learn more about Refrigeration Technologies HERE.

Learn more about Women in HVAC/R and consider becoming a member at womeninhvacr.org/.

Learn more about Refrigeration Technologies HERE.

Learn more about Refrigeration Technologies HERE.

In today’s podcast, Trevor and Bryan discuss how to troubleshoot thermostatic expansion valves (TXVs/TEVs). They also dive into the various types, applications, and components of TXVs.

TXVs are metering devices that control evaporator superheat to protect compressors from harm. Controlling heat also regulates pressure, which improves efficiency and prevents issues like floodback and overheating. TXVs contain several components that manage the forces that open and close the valve. These components include powerheads, diaphragms, springs, and more. The components all contribute to a delicate balance that can be broken when they fail or are installed improperly. TXV failures lead to high or low superheat and eventually compressor failure. 

When you diagnose a TXV, you may encounter hunting, broken powerheads, filthy screens, and improperly sized valves. Once you verify the cause of the issue, you’ll likely have to adjust the TXV, replace a component, or replace the whole TXV. That can be a tricky decision that will largely depend on the type of failure, the type of TXV (conventional vs. balanced port), and the TXV’s application (residential HVAC, refrigeration, etc.).

Join Bryan and Trevor as they cover:

• Opening and closing forces
• Internal and external equalization
• Non-bleed/hard shutoff TXVs and design limitations
• Conventional valves vs. balanced port valves
• Brazing in TXVs
• Strapping the TXV bulb to the suction line
• TXVs in refrigeration vs. HVAC
• Liquid quality, sight glasses, and subcooling
• TXV sizing
• Suction pressure/superheat hunting
• High and low superheat causes
• Adjusting vs. replacing valves

And much more...

Check out Emerson’s HVACR training HERE. Then, navigate to “Contractor Tool Box Talks with Emerson.”

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

This podcast covers refrigeration technologies' growth and focus on providing safe, high-performing chemicals for HVAC technicians without hazardous ingredients.

Mike Pastorello discusses the 2017 rebranding that gave their products a more modern, cohesive look. He also talks about bringing on new marketing talent like Ashley and Becca to amp up refrigeration technologies' social media presence and connect more directly with end users. Throughout, Mike emphasizes enabling the marketing experts to drive strategy rather than micromanaging.

Regarding products, Mike highlights their priority of keeping technicians safe while effectively doing their jobs. He mentions constantly improving formulas to eliminate skin burns, bad odors, and other issues with traditional chemicals. Bryan shares an example from his contracting company where lax safety practices led to an emergency room visit and realigned his team's commitment to using safer alternatives like Viper products.

They also overview popular refrigeration technologies offerings like Nylog thread sealant and the Venom Packs compact container system. Mike states the Venom Packs will avoid upcoming taxes on traditional gallon jugs. Bryan praises the durable, flexible packaging and smaller nozzle.

Bullet points:

• 2017 rebrand and modernizing refrigeration technologies' visual identity
• Bringing on new marketing talent to expand social media reach
• Empowering new hires to take the lead rather than micromanaging
• Keeping technicians safe while effectively doing their jobs
• Continually improving chemical formulas to reduce hazards
• An emergency room visit underscoring the need for safety focus
• Overview of Nylog refrigerant thread sealant
• Benefits of the durable and flexible Venom Packs

Check out all Refrigeration Technologies products at https://www.refrigtech.com/. 

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”

Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 

Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).

Nikki Krueger and Genry Garcia return to the podcast to talk about a recent IAQ & dehumidification case study on a vintage home in Miami. The home was very clean but had a musty odor and VOC concerns. You can read the case study in the “Literature” section at https://www.santa-fe-products.com/about-us/media-resources/ or https://hvacrschool.com/case-study. 

Blower door tests and ZPD revealed that the home was leaky, and the crawlspace was also not properly encapsulated. The options were to tighten the building and/or mitigate the problem by improving the HVAC system. The homeowners chose to improve the HVAC, which Genry did by installing a ventilating dehumidifier (Santa Fe Ultra98H), reducing system tonnage (3.5 to 2 tons), and putting in new ductwork.

One of Genry’s key tips to address intermittent moisture issues is to pay attention to fluctuating pressures, not just under the blower door test conditions. Ongoing monitoring is crucial in these studies to measure the home under several different typical conditions. He also relies on blower door tests to determine if encapsulation is necessary or needs improvement, as insulation and encapsulation can bring new issues in their wake. 

Extensive testing and working with other contractors (such as home insulators) are the best ways to get a solution that makes the homeowner happy. We need a holistic approach to design to achieve a homeowner’s IAQ and comfort goals, not necessarily following strict design guidelines to a T.

Nikki, Genry, and Bryan also discuss:

• Zonal pressure diagnostics (ZPD)

• Dehumidifier ductwork

• Dehumidifier selection

• Attic encapsulation, condensation, and duct leakage

• MAD AIR

• The importance of IAQ case studies and the insights we can get from them

• Effects of insulation

• Dehumidifier performance in part-load conditions

• Mechanical equipment design

• Consulting the ACCA design manuals

• Maintaining equipment and sustaining positive results

Stay tuned for the companion tech tip.

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

This podcast episode is Alex Meaney's 2023 HVACR Training Symposium session: "The Art of Unteaching."

We may have flawed understandings of HVAC concepts, including the understanding that "heat rises." Our world is constantly shaped by the things we see and believe, and we are hard-wired to defend our observations and beliefs if we feel that those are threatened by new information. Instructors need to be sneaky about "unteaching" flawed ways of understanding the scientific principles of HVAC.

When we communicate concepts to others, we need to watch our language and make sure our messages are clear; the subtext is as important, if not more important, than the actual material. Humility also goes a long way when teaching, though teachers need to be especially careful of imposter syndrome. 

Teachers can be most effective when they find a point of common ground between what their students already know and what they want to teach their students; avoiding jargon is a good way to make sure everyone can start on the same page before you teach them the vocabulary. When teaching, think about filling in the gaps without students realizing that those gaps have been filled; some teaching techniques, like inversion, can help with this process. Group settings also make it easier for students to process new information.

Alex also covers:

• Pitfalls of the 12,000-BTU rule
• Bridge vs. bedrock foundation
• Pedantism and cognitive dissonance
• Repeating and rephrasing answers
• The "forgot to know it" approach
• Humility and the "reset button"
• Fallacies and heuristics
• Being able to understand when you're wrong

Check out Alex's design consultation work at https://www.meanhvac.com/. 

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Schooling undoubtedly gives technicians a leg-up once they got into the field. However, the knowledge you gain isn't all practical. Bookwork is still important for a solid foundation in theory, and it would likely benefit a lot of training programs. Bookwork, like trade school itself, is a good precursor to the hands-on material in the field. It also helps to do your research about classes you need to take and to see if a degree is more advantageous than a certificate or vice versa.

Your education won't end upon getting that certificate or degree. In the field, you will learn something new every day (and not in the air-conditioned classroom!). A lot of your familiarity with tools will come from working in the field. However, in trade school, you will learn best practices that you may not learn from other workers in the field.

When you enter the field, invest in your tools. You will work with classroom equipment, but once you enter the field, you will have to develop your own arsenal of tools—research new tools and set aside part of your paycheck to invest in your toolbox.

In many ways, this is the trade with homework. You have to want to learn to be successful in this field. Every day, you will come across new problems that require more knowledge, and nowadays, you have plenty of access to online sources of information to help you tackle difficult problems.

Well-rounded techs come from a solid education and apprenticeships with competent senior techs.

Learn more about Refrigeration Technologies HERE.

In this live recording from the AHR Expo, Kaleb Saleeby, Nate Adams, Michael Housh, and Steve Rogers discuss building performance.

The building science world is an exciting place; we're all excited about improvements to reheat dehumidification, which is when we use waste heat to take care of humidity without cooling. As equipment becomes more efficient, we also look forward to tackling new challenges that make us think more broadly. New people are also stepping up, using new tools, accessing more knowledge, and doing better work.

Building performance is becoming more important in HVAC via HVAC 2.0, which focuses on design efficiency. However, the biggest challenge right now is making HVAC 2.0 sustainable and profitable. We must simplify and scale building performance; when we make it accessible, we can work it into the HVAC industry and do more thorough work.

One of the challenges to widespread adoption is the lack of experience with building performance. The average technician simply doesn't have the needed exposure to building science concepts and practices. Perhaps the best way to bring people into the building science side of the business is to work on the techs' own homes. We need to bring the personal part of building performance to the technicians and their families if we want to see widespread adoption of HVAC 2.0.

We also need to make building performance solutions accessible to the consumers. Although the solutions may be too expensive for many customers right now, the goal is to start holistic comfort conversations.

Kaleb, Nate, Michael, Steve, and Bryan also discuss:

• Tapping into the engineering mindset
• Economic sustainability
• Psychrometric charts vs. app-based learning
• Math vs. software
• Working with techs and the CSRs
• The Gulf of Disappointment
• Contractor relationships
• Economic and environmental impacts
• Fossil fuels
• Upgrading the electrical grid
• Propane

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan explains the science behind adiabatic cooling. Adiabatic cooling occurs in specific HVAC/R applications and in our environment as air temperatures and pressures change.

When we think of cooling, we refer to the loss of heat; we are either referring to the change in the total BTU content of the air mass or the temperature change. Adiabatic cooling takes sensible heat and transforms it into latent heat.

The most simple forms of adiabatic cooling can be seen in cooling towers and swamp coolers. In evaporative or swamp coolers, you have a pad saturated with water, and air moves over it. When air moves over the media, some of the energy helps evaporate the moisture on the pads, so the air loses sensible heat and becomes cooler. The thermal enthalpy (total heat content) stays the same, but some of the sensible heat has transferred to latent heat.

Air that goes through a swamp cooler goes in with higher temperature and lower humidity, and it leaves with a lower temperature and higher humidity. The BTU content stays the same; the energy merely transforms. As a result, we usually only use swamp coolers in arid environments where higher humidity is desirable. You also can’t compare these to compression-refrigeration systems because compression refrigeration aims to change the BTU content and is NOT adiabatic.

When we run air over an evaporator coil, some of the water vapor in the air condenses to liquid water in the drain pan. Some of the energy in the refrigerant changes the state of the water vapor to liquid water instead of changing the temperature. You’ll see a lower delta T when your return relative humidity (RH) is higher.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

Bryan talks about the top refrigerant leak detectors, the best refrigerant leak detection practices, and some good leak detection tips.

Leak detectors require some flow through them. Otherwise, they won't detect leaks. So, these tools have small pumps inside of them to move air through them for sampling. Leak detectors also require some time to warm up, so keep that in mind when you approach a job.

One type of leak detector is a heated diode (sometimes called a heated pentode). It is a heated electronic leak detector that takes a sample and analyzes it within. Infrared detectors also exist, but they require you to move the tool consistently; these tools constantly recalibrate themselves, so you can't hold it still while you're using it to locate a leak.

Once you confirm that you have flow, you need to determine that the detector is actually working. Make sure that your detector can pick up tiny leaks, not just large ones from cracking open a can of R-410a. So, we recommend using leak references that you can use to test your detector. One of those references is a leak test vial.

Some leak detectors have a tip filter, which prevents contaminants from getting into the system. Make sure that your detector has a filter and that you change it regularly. You don't want water or other contaminants getting into your leak detector and breaking it. Another surprising contaminant is leak bubbles; these bubbles can also set off a leak detector, so be careful to manage your order of operations to avoid false positives.

These tools work best if you store them in clean, dry places. It is also a good idea to keep a backup in case your main leak detector breaks or loses accuracy.

Learn more about Refrigeration Technologies HERE.

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Corbett Lunsford from the Building Performance Workshop and the Proof is Possible tour talks to us about the moral superiority of building performance testing, blower door testing, and much more.

Building performance and HVAC have been becoming much more closely linked lately. So, it's a good idea for HVAC techs to learn a bit about building performance.

In the HVAC world, we often see homes with extremely hot upstairs portions and cool downstairs questions. That is a complex building performance issue. A good contractor can troubleshoot the issue with the building and find cost-effective ways to improve the enclosure (air ceiling and insulation) and the HVAC. The construction and improvement industries will be utilizing diagnostics and metrics, much like most of the HVAC industry today. (Metrics that we use include static pressure, superheat, subcool, etc.)

The blower door is the most important tool for diagnosing issues with the enclosure. Many odor and comfort issues deal with ventilation, not just the HVAC. As such, blower door testing can help diagnose issues that don't go away after improving or repairing the HVAC system. Air leakage is the most important issue that occurs with the enclosure.

A blower door test replaces the front door with an airtight shroud with a fan mounted inside. That fan then hooks up to a manometer to measure pressure in the home with reference to the outdoor pressure. The blower door drags the pressure down to 50 pascals, and then you can see how much air goes through the fan at that constant pressure. The air that comes through the fan indicates a lack of airtightness in the home. However, blower door testing requires practice and repetition. If you get one, practice with it before you use it for diagnosis.

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In today’s podcast, Eric Kaiser and Bryan talk about mentorship in the HVAC industry. They discuss what it means to be a good mentor, how to find a good mentor, and what it means to be mentored. 

Mentorship is an organic process. Most mentees don’t go up to someone they respect and formally ask that person to be their mentor. Respect is the foundation of the mentor-mentee relationship; formal mentorship often resembles friendship in many ways. 

However, mentorship can take more forms than the traditional mentor-mentee relationship. In the digital age, podcasts and YouTube channels that readily share information about a skill are resources that can fulfill the same role as a traditional mentor.

A good mentor has a willingness to explain the how and why behind a question or process; they don’t give simple answers. Good mentors must also be able to provide resources for their mentees; they know the limits of their knowledge and are willing to find those answers with their mentees. Often, the better mentors are humble and don’t flaunt their experience. Good mentors want to see their mentees do well and grow; they don’t want their mentees to follow and copy them.

The support in the relationship goes both ways. The mentee must want to support their mentor, not compete with them. Mentees must be willing to start conversations and ask for clarification; an ineffective mentee waits for answers to be spoonfed to them. Good mentees are also willing to challenge their mentors at times [respectfully]; they don’t excessively flatter their mentors.

Bryan and Eric also cover:

• Personal growth
• Online mentorship resources
• Cultish mentors
• Outgrowing and leaving mentors
• “Stealing” in mentor relationships
• Unproductive mentorship
• Honoring mentorship

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Camron Conlee joins the podcast to give us an introduction to ammonia chillers. He also explains what it's like to work with a poisonous refrigerant. The California division of TDI Refrigeration, where Camron works, primarily works on ammonia systems. We often see ammonia refrigeration in cold storage and food processing; ammonia refrigeration is usually in industrial applications away from the public.

Ammonia is more hazardous than CO₂ and other refrigerants because it is toxic. When working on ammonia chillers, the most important thing is to keep the ammonia inside the pipes. You may even need to wear full-face respirators and personal monitors when working on potentially leaky ammonia systems.

Ammonia chiller oil systems are a bit different from R-22 systems. Oil separation is important in both ammonia and R-22 refrigeration, as ammonia systems typically use coalescing separation methods to isolate oil from the refrigerant. However, the oil generally doesn't mix with ammonia as readily in the first place. Some systems rely on pressure differentials to move liquid, and others use pumps to move liquid ammonia into the evaporator.

Preventive maintenance on ammonia systems is quite similar to PMs on other types of refrigeration systems. Compressors are also important components that require occasional maintenance. Like many other commercial refrigeration systems, several ammonia chillers have hot gas defrost.

The ammonia refrigeration world has a few different types of job opportunities. Some companies require in-house operators, but there are also external service companies, which may have a few smaller customers. In almost all cases, these jobs require technicians who can stay calm in crisis situations, as there is a lot at stake.

Camron and Bryan also discuss:

• Recirculated vs. gravity-fed systems
• High vs. low-pressure receivers
• Dry vs. wet suction
• Screw compressors
• Copper and brass leaks
• Finding ammonia refrigeration companies and trade schools

Find out more about TDI at tdirefrigeration.com.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan covers the bypass factor in airflow and psychrometrics. He also explains why it matters to techs.

The bypass factor is a ratio: you take the difference between the evaporator coil temperature and outlet air temperature as compared to the inlet. In other words, you find the difference between your TD and delta T.

When air moves over the coil, only some of it contacts the coil's surface. Therefore, only some molecules will become the same temperature as the coil. Other air molecules will bypass the coil, which typically happens when coils have a lower surface area. Evaporators have fins to increase the coil surface area, which helps those air molecules bump into the coil and transfer their heat. Without those fins, your performance will suffer; the saturated suction temperature will drop, and your temperature split will be lower, indicating a higher bypass factor. We want that air to have MORE contact time with the coil; therefore, we want a LOWER bypass factor.

However, when we account for total enthalpy change across the evaporator coil, we also have to look at the latent content; that topic can get complicated and theoretical very quickly, so we avoid that discussion for the sake of simplicity.

The bypass factor also accounts for contact time, which is the amount of time needed for the air molecules to transfer their heat to the refrigerant. You can reduce air velocity to increase the contact time, which is the inverse of the bypass factor.

Bryan also covers:

• Coil types and impacts on bypass
• Impacts of coil size on dehumidification
• CFM adjustments with varied coil sizes
• Sensible heat ratios (SHR) and installation considerations

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Learn more about Refrigeration Technologies HERE.

In this short podcast episode, Bryan answers a listener-submitted question: How do inverter air conditioners work?

Inverter-driven systems have variable capacity to match loads. We can provide cooling or heating BTUs to match the needs of the space without overcompensating or undercompensating and causing temperature swings. Load matching also helps us get better efficiency out of the system. High-humidity climates also benefit from load matching, as equipment doesn't dehumidify well unless it has been running the entire time.

When set up and designed properly, variable frequency drives (VFDs) improve comfort, efficiency, and even dehumidification. You can "overclock" your compressor to get more BTUs out of it without oversizing, particularly when you have high heating loads due to the cold weather.

Inverter-driven equipment takes AC power in, runs it through a rectifier circuit, and turns it into rough power that resembles DC power. The current is then smoothed out and goes through the inverter bridge circuit. Unlike an analog AC wave, we rely on pulse-width modulation (PWM) to simulate three-phase power and control the motor speeds according to a space's needs.

We typically troubleshoot residential inverter-driven equipment by following the manufacturer flowcharts and possibly by communicating with tech support. Commercial VFDs are external to the motors and tend to be a bit more universal rather than manufacturer-specific.

Watch the livestream about VFDs & inverters with Matthew Taylor and Corey Cruz HERE, and you can also watch the livestream about cold climate heat pumps with Ross Trethewey and Russ King HERE.

Learn more about NCI's High-Performance HVAC Summit at https://www.gotosummit.com/. 

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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In this episode, Bryan talks to Business and Sales Trainer Bob Gee about HVAC business practices.

Bob has watched sales and leadership evolve a lot over the years. Today, success in sales depends on your abilities to build relationships with the customers. You're no longer "selling" things; you are "helping people buy" things. Instead of pushing products to people, it's best to "ask your way into a sale" and prioritize a customer's wants and needs. There is also a stark difference between management and leadership. A leader is people-oriented and customer-oriented; they care about the human element of business, not just crunching numbers.

When it comes to building a company culture, the company leaders have to be the ones to create the team. You have to get the right people on board and delegate them in a way that maximizes those people's potential. Business leaders also need to examine their own purpose. Why are they running the business? Do they want to commit to the business, or did they just decide to work independently to have more control over their own schedule? Motives mean a lot, and the managers' attitudes trickle down.

Firing people and having people leave are unfortunate but inevitable parts of running your own business. People tend to leave people; they don't necessarily leave the business because of the money or the type of work. Employees have to be on board with the managers' ideas of what the company is doing and where it should go. If they are not on board, they will quit or may have to be let go after their work quality slips over time.

Follow Bob Gee HERE.

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In this short episode, Bryan goes over the fourth chapter of his new book, Unconformed. The chapter is called "So... What Do You Do?"

Parents always want to be proud of their children, but it seems as though children are more proud of children who attend college than take up apprenticeships. However, these feelings largely seep in due to peer expectations; we want our children to measure up to our friends' standards or success, not necessarily our own. Parents are also less likely to encourage their children to get into the trades and value the time and expertise of tradespeople.

All jobs, even less prestigious jobs, matter and have a purpose. Society tends to devalue tradespeople and manual laborers, but those jobs do a great service to society. Nevertheless, the competitive drive between parents and our fear of failure makes us fall into these mindsets where we devalue manual labor. The media and family members also trap us in these expectations.

Society runs on the ability of people to solve problems and innovate, which means that blue-collar work is necessary for society to function. Not to mention, popular media and DIY culture have also brought attention to the artistry of the skilled trades. These positive changes are important to the perception of blue-collar work, and we can accept (and encourage) a child's choice to find purpose in the skilled trades, not just blindly seek happiness.

Bryan also covers:

• Networking
• Expectations vs. standards
• The pitfalls of happiness
• The merits of working with our hands

You can purchase Unconformed on Amazon's website HERE.

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

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