HVAC School - For Techs, By Techs

In this episode, Bryan speaks with Eric Shidell about some of the basics of system freezing, what causes it, and what to do about it. Freezing is a normal part of some equipment, such as low-temperature freezers and outdoor units on heat pumps. On straight-cooling systems, freezing is NOT normal and indicates poor operation. Ice formation starts on the evaporator coil and may spread to the compressor via the suction line. The best way to remove ice and defrost the system is to pull the disconnect on the outdoor unit but let the indoor fan keep running. Or, you could turn the unit off but leave the fan on. The goal is to defrost slowly and steadily. Defrosting too quickly could potentially cause damage. Horizontal air handlers in the attic can flood the home if ice forms and melts off too quickly. In an upflow furnace, defrosted ice could damage the electrical components. You will typically find low suction pressure on frozen systems. Many technicians who merely attach gauges and don't thoroughly inspect the unit for freezing will mistake the low pressure as a result of a low refrigerant charge. However, low pressures are a SYMPTOM, not the cause of freezing. Freezing is generally caused by poor airflow over the evaporator coil. As frost appears on the evaporator coil, airflow will be further impeded. On top of that, the suction pressure drops even more. From there, all of these factors feed each other and cause the frost to snowball out of control (almost literally). Sometimes, coils may freeze due to low refrigerant, but the amount of ice will typically be minimal compared to freezing that occurs due to an airflow issue. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

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

In this episode of the podcast, Bryan talks with Andre Patenaude from Emerson about CO2 refrigeration, and transcritical booster systems. Modern CO2 systems are efficient and effective due to their electrical controls and components, including case and high-pressure controls. Carbon dioxide (CO2) is a good refrigerant to address global climate change. From a sustainability standpoint, carbon dioxide is a superior refrigerant to HCFCs and HFCs. Carbon dioxide is also an A1 refrigerant, meaning that it is non-toxic and non-flammable. It is also inexpensive and compares to HFCs in cost. Unfortunately, it can rapidly change pressures and is more efficient in lower ambient temperatures. Overall, CO2 is a desirable refrigerant as we address the challenge of sustainability but is not without its challenges. During the refrigeration cycle, carbon dioxide's critical point comes into play. In hotter ambient temperatures, the carbon dioxide's temperature and pressure may exceed the critical point. The refrigerant then becomes a supercritical fluid; the pressure and temperature change independently of each other. Accessing the supercritical zone is also known as "transcritical." Carbon dioxide refrigeration is best for low-temperature grocery refrigeration. It has also worked its way into industrial refrigeration. However, the greatest challenge revolves around the condensing temperature. Carbon dioxide must reject its heat to something that is much colder than it. A transcritical booster system's condenser becomes a gas cooler in the summer; instead of leaving the condenser as a liquid, a CO2 system leaves the gas cooler as a supercritical fluid. It becomes liquid when it passes through an electronic expansion valve (EEV) before the receiver. The CO2 refrigeration system also contains a flash tank and a bypass valve. The bypass valve partially dictates which compressor the refrigerant fluid travels to. There are also low and medium-temperature evaporators and compressors. Resources Seven Keys to Servicing CO2 Systems - Article by Andre CO2 Booster Systems Introduction - Article by Bryan Cascade Refrigeration - Article by Bryan Emerson CO2 Application Guide

In this just-for-fun episode, we celebrate 10 years of great tools and excellent customer service with TruTech CEO Bill Spohn. We hope you enjoy this lighthearted episode with some discussions about company culture, superior service, and a commitment to quality. TruTech's approach to service goes more beyond selling the tool. The engineers at TruTech aim to learn how technicians plan on using tools. Those engineers want to use their technological expertise to create products that make technicians' lives easier in the realm of diagnosis and measurement. TruTech Tools also works to honor its relationship with the HVAC community and market. The engineers at the company see the value in the relationship between HVAC and building performance. TruTech Tools also carries trusted brands, such as Testo and Carrier. When it comes to pricing, TruTech Tools believes in pricing based on the market price and backing up the product with superior service. Most of a product's value comes from the seller's service. TruTech Tools also remembers to reward loyal audiences and buyers with discount codes or rewards systems. Bill Spohn also wants TruTech Tools to develop some more educational materials in the future. The company has a close relationship with the HVAC industry and wants to show its support through a commitment to training. Overall, TruTech Tools values its connection with the HVAC community and takes pride in its standing as a trusted tool provider for such a great community. Check out TruTech Tools at trutechtools.com and use the offer code "getschooled." 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, Bryan talks with HVAC products designer Adolfo Wurts about technology, automation, and the coming robot apocalypse. Automation is a fear in many industries, and the HVAC industry isn't alone. Today, we talk about how instrumentation and AI technology may develop and what that will mean for the future of the industry. Some recent practices that have severely impacted the job market lately have been globalization (where work moves overseas) and automation (where machines replace human labor). Globalization is not a major threat to our industry due to the local nature of our jobs. However, automation seems like a more valid concern. Automation has been occurring for a long time; it started off by replacing animal labor with vehicles at the beginning of the Industrial Revolution in the 1800s. Machines have also slowly been replacing repetitive human tasks. Some high-wage professions have already been replaced by technology, including tax preparers and travel agents. That is because those people make high wages, and automation makes sense economically. Conversely, the cost to replace a fry cook with a robot would probably exceed the amount of money it would save in wages. However, humans use their senses to solve problems; machines cannot make judgments based on sight, smell, sound, etc. HVAC techs use those senses to diagnose issues with the system. So, HVAC techs would be very difficult to replace with robotic technology. The customer service element of HVAC work, especially listening skills, would also be difficult to reproduce in a robot. So, we have lots of assets that technology cannot replace anytime soon. Bryan and Adolfo also discuss: Maintenance vs. healing Datasets, algorithms, and robots Technicians that will be automated before HVAC techs Variable vs. standardized technology (homes vs. cars) The concern of "dumbing down" techs with smarter diagnostic equipment If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe 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.

In this episode of the podcast, Jim reviews the basics of evacuation and dehydration. He also covers hoses and vacuum gauge placement. Evacuation may just seem like a method to suck air and water out of a system. However, it is an intricate science that lacks a lot of detail in most trades education programs. The deepest vacuum we can possibly pull merely offsets the atmospheric pressure and is actually not that deep; the deepest possible vacuum is -14.7 PSI (-29.92" Hg). The evacuation rig is the most important element of evacuation. If you want a fast evacuation, DO NOT use 1/4" hoses or manifolds. However, those are both common practices in the HVAC industry. The only way to increase the flow of refrigerant, air, and water out of a system is to increase the hose diameter. Larger hoses have less resistance than smaller hoses. Pump size does not seriously impact evacuation speed when compared to hose diameter and the presence/absence of Schrader cores. Schrader cores are other major sources of restriction, and you'll want to use core removal tools. Air from a vacuum pulls in a localized area. As such, it is a BAD idea to hook your vacuum gauge up at the vacuum pump. You are measuring the pressure of the pump, in that case, NOT the whole system. When you read 500 microns at the pump, the real pressure of the system could be over 1000 microns (especially if you have 1/4" hoses). Bryan and Jim also discuss: Atmospheric pressure Connectors What is a "good" vacuum? Decay tests Moisture throughout the system and its effects on decay Water's state changes and vacuum Sublimation and ice during an evacuation Capping off, soldering, brazing If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode of the podcast, Jamie Kitchen from Danfoss talks about wet-bulb, dry-bulb, relative humidity, dew point, enthalpy, and latent heat. These are the building blocks of psychrometrics, which deals with human comfort as it relates to temperature, humidity, and heat loads. Humidity is water vapor in the air. As the air's dry-bulb temperature increases, the more water vapor the air can hold. That is partially why dew is more common on cold mornings instead of hot ones. However, the air's weight does NOT increase with more water vapor; moist air is less dense than dry air. Moist air has more heat energy than dry air, though. Relative humidity (RH) is the percentage of moisture that the air can hold before saturation. Saturation occurs at 100% RH. In psychrometrics, there are two different types of relevant temperatures: dry-bulb and wet-bulb. Dry-bulb temperature refers to true thermodynamic temperature; humidity doesn't affect the reading. Wet-bulb also accounts for the rate of evaporation in the air; it accounts for the body's ability to cool itself through evaporated sweat. When the wet-bulb and dry-bulb temperatures are nearly identical, that means that the RH is high. We have psychrometrics charts, and we can plot points based on wet-bulb and dry-bulb temperatures. These charts also have a "dew point" on them, which is the point where the air can no longer hold more grains of moisture. That moisture then condenses into dew or fog; this point is saturation or 100% RH. Dry-bulb and wet-bulb temperatures will be the same at the dew point. Bryan and Jamie also discuss: Absolute moisture content (moisture grains) What Willis Carrier understood Evaporative or adiabatic cooling TXVs vs. fixed-orifice metering devices and temperature Sensible vs. latent cooling Commissioning equipment for comfort If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan and Jim discuss measuring voltage drop and what it means. They also cover some other pointers to keep from using parts to bandage a deeper issue. A common mistake that technicians make is not understanding what an ideal measurement is before making a measurement. For example, they may not know what the refrigerant pressures should be before they attach the gauges. Electrical measurements are the same, and voltage drop falls under that umbrella. Voltage refers to electrical pressure, and current refers to electrical flow; they are two different values. The voltage will typically be at its full value (e.g., 240v) until you test the system under load. The voltage will drop when the motor begins turning. A motor will generate either motion or heat. When a motor doesn't have enough electrical pressure (voltage) to start, it will generate heat until it trips an internal overload. Upon startup, a standard voltage drop will be around 20% on a properly sized circuit. When the unit drops voltage in excess, the compressor turns more slowly and reduces its output. Many technicians measure voltage to see if it merely exists. They do not attempt to see if the voltage is at an appropriate level, and that's a major pitfall in our industry. Technicians ought to know the appropriate voltage values so that they can assess if the voltage drops are normal or excessive upon startup and while a compressor is running. Common issues that cause excessive voltage drop include: Excessive heat loads in the building (from other electrical appliances) Undersized feed wires from the transformer to the pole Loose lugs Corroded connections Conductors that are too small or too long Before bringing out the hard start kit, make sure you do all of the preliminary checks to make sure you REALLY need it. Make sure the feed wire is the correct size and that your connections are solid. A hard start kit will mask the issues of voltage drop for a short time, but they don't address the core issue. So, just check voltage drop under load. Voltage drop should not exceed 20% on startup and 3% while running. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast, Jeff Neiman shares an overview of his chiller startup procedure and some things he looks out for when starting a chiller after the initial chiller installation. The actual chiller startup is typically the factory's responsibility (per the manufacturer); however, the "startup" that we're talking about refers to the installation and early maintenance. The first step is preparation. Neiman recommends having a copy of the installation manual and reading it beforehand. You should also have a "request for startup" or pre-commission checklist. You also want to make sure there is water in the system before starting up a chiller. Technical datasheets are also useful to have on hand. Once you get to the job site, inspection will be your main job. You can look for dents in the coils and other signs of damage from shipping or mishandling. Review the installation location. Make sure there is proper clearance around the chiller. As with other HVAC units, liquid in the compressor is catastrophic. So, make sure that the screw compressor is warm and liquid-free. Although centrifugal chillers have separate oil systems, heat is also important in those chillers because it warms the bearings. Next, you can open up the panel and check the power. Perform a voltage imbalance calculation to make sure your voltage is satisfactory. Check for proper wire sizing and the number of conductors. Check that the piping has been done properly for the flow direction. The condenser fan has set screws, and it would be wise to verify their tightness. Then, you check your water flow to make sure it fits all the correct parameters on your technical datasheets. Check the valves, flow, and pressures as specified. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan speaks with James Bowman from Rectorseal about hard start kits, PTCR devices, run capacitors, compressor overheating, and the Kick Start product. We also go pretty in-depth on potential relays and how they operate. Hard start kits are mechanical potential relays connected to a capacitor, and they aid in starting the compressor. They come in two-wire and three-wire types. However, they have some pitfalls. For example, they are easy to abuse. You may also come across a "hard start kit" that does not have a mechanical potential relay (such as a PTCR), which is not a true hard start. Many of those false kits are low-quality and borderline dangerous. The start cycle starts in approximately 0.4 seconds. A proper hard start kit will help the compressor start in less than 0.4 seconds. Two-wire electronic start kits don't react quickly enough and cannot remove themselves from the circuit in time. Two-wire mechanical potential relay kits, on the other hand, measure voltage between run and start, unlike a three-wire device that measures the voltage between common and start. Three-wire devices are typically okay, but they are not a universal component that can fit every unit. Rectorseal's Kick Start kit is an aftermarket kit designed to work on most units as a replacement for the OEM kit. When dealing with aftermarket hard start kits, the best practice is to know your equipment and the hard start kit's compatibility with the unit. Hard start kits work especially well with reciprocating compressors with long line sets and HVAC systems with hard shutoff TXVs. Bryan and James also discuss: Potential relays Back EMF Start capacitors Testing run capacitors under load and with meters Looking at systems holistically Copper plating inside compressors For more information, go to rectorseal.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In part 2 of this conversation, we go through the condensing unit and wrap up the call with our no-fluff customer service best practices. The service call A thorough inspection is critical on any residential service call. A service call is an opportunity to check the integrity of the unit and the cleanliness of the blower wheel, drain, and other components. Check the charge, safeties, and five pillars. List the problems and present the solutions as suggestions. Provide appropriate timetables and provide all necessary information. If possible, you can let the customer watch you work on their system to build that trust and teach them about the unit. If the customer gets worked up over the pricing or frustrated over something with their unit, own the frustrating circumstance. Make sure you stay calm and rational with them. Remember, you are a consultant that they should trust, and it is best to be empathetic and professional at all times. When exiting the call, try to move on without spending too much time chit-chatting with the customer. Offer to answer questions by giving your contact information or the office's contact information.

This is part 1 of 2 on the soft skills practices of approaching and completing a residential service call in the best manner possible. Before the service call and good housekeeping Before a technician even leaves to go to work, they need to get their head in the game. Be ready to face the day by showering, shaving, and brushing your teeth. Having self-respect is also a sign of respect for the customer. The drive to work is a good place to clear your mind; you can listen to podcasts or do other things to get yourself in a good place to work effectively. Getting to work early is also a good practice. At the beginning of the workday, you can get a coffee, restock your truck, and fuel your truck to start your day with everything you need. When going to a customer's home, make sure you have reviewed the history of the unit and get there on time. Exit your truck as soon as possible; customers expect prompt service. Introduce yourself politely and listen to what the customer says. Respect their home; don't leave your trash on their property, don't smoke, and be careful not to let the smell of cigarettes bother the customer.

In this podcast episode, Bryan talks about grounding and some common misunderstandings related to ground, neutral, ground rods, and lightning. The common phrase that "current goes to ground" is a myth. The transformer (or the power source) that feeds a building creates a potential difference in charges (voltage); current is the motion of electrons between a difference in charges. A transformer has three terminals: two legs and the XO terminal (neutral). You have 240 volts between legs and 120 between each leg and the XO terminal. The leg of power going into the transformer is split into two in a single-phase application, so the sine waves are completely out of phase with each other. When you connect to a transformer, all of the power is either a balance between the two legs or is between the legs and the XO terminal (neutral); it NEVER goes to ground. If any power is traveling to "ground," it is traveling to the ground and going back to the source because there is no other path. Power travels to the ground and then to the source when neutral isn't properly bonded to ground. Another common myth is that the current always takes the path of least resistance. The current does not always take the path of least resistance; it may take all appropriate paths. All equipment is grounded to create a ground fault (this is called "grounding"). Then, it should be connected to a ground rod. Grounded assemblies attempt to dissipate high-voltage occurrences, such as lightning strikes and massive surges from distribution lines. Lightning is a very high-voltage DC phenomenon that can be fatal to people or equipment. So, dissipating electromagnetic pulses to ground is much safer. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bryan talks with Nick Messick about some ice machine basics. They also discuss how to determine when to pick up the phone and call tech support. Ice machines have the same basic refrigeration circuit as HVAC systems. However, ice machines require a much different cleaning regimen. Many maintenance people neglect ice machines by using incorrect cleaners. You need more of a sanitizer than a cleaner; sanitizers kill germs and fungi, but cleaners work better on corrosion. When cleaning an ice machine, watch out for mold and scale buildup. Scale buildup is especially problematic because it hardens the water. You can use ice thickness probes or listening devices to determine the condition of the water (and ice). Also, use a nickel-safe cleaner, like Refrigeration Technologies' Viper Nickel Safe. Ice machines have "harvest cycles" where ice collects. Ice falls off the evaporator when warmth hits the evaporator. An ice machine may use hot gas or "Kool gas" defrost. Hot gas defrost reverses refrigerant through the cycle and sends discharge gas to the evaporator. Manitowoc systems use Kool gas, which uses saturated vapor at the top of the receiver and results in a quieter harvest. Tech support can really help you if you can't understand the manual or get stuck. However, some techs let their pride prevent them from calling tech support. Ultimately, calling tech support to help you understand an ice machine will save you time and save the customer money. You can also walk away from a situation having learned something new for next time if you call tech support and let them help you. However, calling tech support should NOT be a crutch that techs depend on all the time; basically, don't let them be your autopilot. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode of the podcast, we talk about condenser wire sizing considerations, ampacity, temperature, conductor sizing, voltage drop, and why a #10 wire doesn't always require a 30-amp breaker. There's usually nothing wrong with OVERSIZING a wire or conductor. However, you still need to know which wires are safe for operation and comply with the National Electrical Code (NEC) protocols. Relatively small conductors can carry relatively high voltages. Instead, amperage dictates the size of the wire. Therefore, we use ampacity (amp capacity) to determine the size of a wire. Transformers are a perfect example; wires going into the transformer are small, and wires leading out of the transformer are larger. You also size circuit breakers, fuses, or overcurrent protectors to protect the conductor. The wire type that goes into a breaker depends on several variables. Some of these variables that affect ampacity include wire material, insulation rating, ambient temperature, and how many other conductors are in the same metal area. Thus, rules of thumb for wire sizing are not reliable. If the ambient temperature exceeds a wire's rating, you can derate a wire by using a multiplier; use the values in Table 310.15(B)2(a). A major concern for wire sizing is the probability of a short circuit. The term "short circuit" is often misused to describe ANY sort of electrical failure, but that is not the case at all. "Overcurrent" or "ground fault" is a more precise term for excessive amperage. Overload conditions indicate that the load is too large, so high amperage is drawn. Compressors draw the highest amperage out of all HVAC system components. Overall, size your conductor by minimum circuit ampacity and your breaker based on maximum overcurrent protector If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode of the podcast, we talk to Bill Spohn from TruTech Tools about how TruTech Tools got its start and some of the ways that techs and engineers approach problems differently. Bill Spohn is a majority owner of TruTech Tools who became invested in the HVAC field in the 1990s. The beginning of TruTech Tools was a milestone in Bill's professional journey. After working at Superior Valve for a few years, Bill moved to Testo. While Americanizing many of Testo's products, Bill Spohn met Jim Bergmann. A German Testo employee advised Jim Bergmann's father to set up an online store for the Testo products and other HVAC tools. That website later became known as TruTech Tools. Jim, his father, and Bill were at the forefront of the new company. Bill contributed to the development of TruTech Tools through his product and marketing knowledge. Since then, TruTech Tools has grown a lot more. Jim Bergmann has since moved on, but he is still friends with Bill and remains a major figure in the instrument development and testing part of the HVAC industry. Bill considers himself to be an engineer. Unlike technicians, engineers have a deeper level of expertise in the development of tools and products. However, technicians have greater field knowledge and provide valuable feedback for engineers like Bill. Engineers know the math behind their products and how to use those products. However, technicians provide the practical element to tool development. Both technicians and engineers must be humble to work well together, exchange ideas, and technologically progress. You can always get a great discount from Trutechtools.com by using the offer code getschooled at checkout. Check out our handy calculators HERE.

In This episode Justin talks about the trials and benefits of working out of town, long drives and this weeks boiler service calls in detail.

Jesse and I talk about MORE best practices for installing ductless systems. Both lines should be insulated on a ductless system because they have electric expansion valves in the outdoor unit. Insulating flares is also a critical task. When it comes to flare fittings, overconfidence is a tech's biggest enemy. Techs often undervalue the process of reaming copper or overdo it. Bubble-testing the flare joints is always a best practice to evaluate the integrity of your flares and check for leaks. Do not braze copper on ductless systems! Ductless evacuations require deep vacuums. Removing cores and valving off are best practices for evacuation; the goal is to reduce the risk of contamination, just like normal split systems.

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.

In this episode with BENOÎT MONGEAU, we talk about the components of combustion and what to consider when testing it on a fuel-burning appliance. Combustion requires fuel, oxygen, and a heat source in a correct balance. We call that series of requirements the "combustion triangle." Once combustion occurs, it is self-sustaining. However, removing one element of the triangle will end combustion. (For example, you could suffocate a flame by removing the oxygen content.) Undesirable consequences of incomplete combustion include the production of carbon monoxide, a potentially fatal gas. Flash point is the temperature at which vapors can ignite. Excess air is the air that you're inputting into flue gas that doesn't get used for burning. It contains nitrogen and oxygen and doesn't contribute to the burning. However, it does expand the volume of the flue gas and absorbs heat. Excess air indicates a loss of efficiency and colder gas. (Note: Perfect efficiency is theoretically possible but impractical.) High-efficiency furnaces have longer run times, which may confuse customers; customers may think that the longer run times mean that there is something wrong with their heating system. Natural gas is mostly methane, so it is easy to burn with the right amount of oxygen. Propane (liquid petroleum) is a larger molecule with three carbons. Propane requires more time and more mixing for proper burning. The larger the molecule, the more time you have to spend waiting for combustion, and it's harder to burn the molecule completely and properly. Benoit uses Testo combustion analyzers and TPI digital manometers when working with furnaces. He uses heat-rise calculations whenever he wants to calculate CFM on a furnace. CFM tables are in the manufacturer's manual. As always, if you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode Justin talks about his first A/C repair of the season, his old combustion analyser and why he is enjoying the Testo Smart Probes his just got

Dan Holohan speaks to Bryan about his background and journey as a writer. He also dives into his book, Pumping Away, and describes classic hydronics as he does in his book. Bryan and Dan also briefly discuss the difference between search and research. Dan is a prolific writer, and one of his most famous works is The Lost Art of Steam Heating. However, this episode primarily focuses on Pumping Away: And Other Really Cool Piping Options for Hydronic Systems. Although Dan has retired, his daughter has ensured that his books will continue to remain in publishing for years to come. Pumping Away is about the piping genius of Gil Carlson. Carson was one of the founding fathers of hydronics. Carson's main contribution to hydronics is the idea that circulators need to pump away from compression tanks. Hydronics systems use steam, hot water, and gravity furnaces for heating. Boilers and radiators were not common in the public sphere at that time. As Dan describes in his book, hydronics is a relatively old technology. Many American buildings used hydronics to control the temperature in buildings before the days of World War II. Dan's conversational prose and easy-to-understand drawings bring hydronics to life in his readers' minds. Dan's advice for the new generation's technicians is to recognize their value. When young people recognize their value, they can take ownership of their knowledge. However, empowering the next generation also requires new technicians to share their knowledge readily. The trade thrives when technicians share their knowledge and don't see the trade as a competition where people try to get a jump on each other. Once you are done listening, please head over to heatinghelp.com. As always, if you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

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.

In this episode, Ruth breaks down some of the main things an A/C contractor needs to consider when looking at their numbers and some of the major leaks that can lead to unprofitability. Profit and loss (P&L) statements are critical for determining the profitability of your business. You can use it to find money "leaks" in your business model. When making P&L statements, ensure that the revenue AND costs for a given product are in the same month for best accuracy. Most small businesses don't look at their profit and loss statements at least monthly, which is the best practice for keeping track of money via a P&L statement. Most businesses also don't separate overhead from cost of goods sold. Overhead costs don't DIRECTLY contribute to the business's revenue. Examples of overhead include rent, electricity bills, and office staff paychecks. Some other common profit drains include marketing and insurance expenses. However, perhaps the largest potential money drain is a lack of employee productivity. A vast majority of small business employees "steal" from their employers by using work time for personal activities. You also want to run your business on an accrual basis than a cash basis. You can keep better track of your expenses and income automatically, not ONLY when you pay your expenses or when money comes in through the door. QuickBooks makes this an easy process. You know that your business is profitable if your P&L statements end up with a positive number. On top of that, you can determine your net profit per hour. Take your net profit and divide it by billable hours (no vacation time, office staff wages, etc.). You can see all of Ruth's content and courses HERE. Make sure to use the offer code HVACRS with all caps for a great discount.

Tersh and Bryan were both techs working for other companies when they started their own businesses. This episode is a look back at what they got right, what they got wrong, and the top things that have worked over the years. In general, there are two types of HVAC business owners: the sales/business type and the technical type. Bryan and Tersh are both of the technical variety. These types of owners may be less familiar with the ownership and business organization side. Many current technicians will find themselves in a similar position if they decide to go into business. The HVAC industry is NOT as profitable as many people imagine it to be, especially in the early years. Tersh recommends that technicians really research the expenses of HVAC business ownership, namely worker's compensation, general liability, licensing, fuel expenses, and advertising. He also recommends that business owners use digital media to assist their business operations. Bryan encourages prospective business owners focus on their financial literacy. You can be excellent with customer service and can draw many customers to your business, but those qualities don't matter if you can't manage your money effectively. Business owners need to understand what profit REALLY is, how margins work, and how to evaluate and nurture a successful business model. Also, business owners should track labor rates and know who to compete with; don't compete with businesses that do bad work or are going out of business. You must also have good people skills if you want to start an HVAC business. If you cannot be empathetic and build relationships, running an HVAC business isn't for you. Bryan and Tersh both agree that the best overall mindset for an HVAC company's business model is "People over profit." That includes service technicians, customers, and all staff.

In this episode, Bryan speaks with Jim Bergmann of Redfish Instruments about his path to being a test instruments business owner. He has also worked with Testo and has teaching experience under his belt. In the past, test instruments were low-resolution and often inaccurate. Many HVAC techs of the past based all of their knowledge on inaccurate measurements. We also didn't use many of the best practices we use today. For example, technicians used tap water for sling psychrometers, not distilled water. As such, technicians of the past had serious issues with wet-bulb enthalpy calculations. Some of these challenges stemmed from issues with the educational system. There was a lack of emphasis on the fundamentals and measurement and an overemphasis on installation, and the poor curriculum still persists in some institutions. Today, Jim sees a large understanding gap between the engineers that develop test instruments and technicians in the field. As a business owner who developed some of those testing technologies, Jim's goal is to close the gap. In the future, Jim believes that the HVAC labor shortage will be a challenge for test instrument developers as the industry moves forward. Due to issues that remain in the HVAC education system, Jim also worries that the people who enter the field will be "parts-changers;" they won't check the system thoroughly for a proper diagnosis. So, Jim has been working on a diagnostic tool called MeasureQuick to help new technicians by educating them on what their readings mean. These technologies are meant to help entry-level techs and aid intermediate and senior techs. Here's a bonus note about measuring with pitot tubes: use longer hoses and an instrument with a very high resolution. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast, Bryan talks about condensing temperature, condenser split, and subcooling. All three of the values are proportional. If one changes, all three of them will change. Saturation is also a critical concept that relates to all three of those, so we also cover those relationships. As you remember, a condenser rejects heat and turns vapor refrigerant back into a liquid. Condensing temperature is the saturation temperature at which the refrigerant changes from vapor to liquid; it can change depending on ambient temperature. While in the condenser, the refrigerant will be at saturation and be a liquid-vapor mix throughout most of the coil. Subcooling indicates how low a liquid is below liquid-vapor saturation. For example, if you had a condensing temperature of 110°F and took a liquid line measurement of 98°F, you would have 12°F of subcooling (110 - 98 = 12). Although some high-SEER HVAC systems may get their liquid line temperatures pretty close to the ambient temperature, you cannot have a liquid line temperature below the ambient temperature. Otherwise, you probably have a restriction in the line. Many technicians set a charge based on subcooling. Condenser split is a bit trickier to define. You DON'T compare the temperatures of air going into the condenser and air going out. Instead, it is the difference between the condensing temperature and the outdoor temperature. The outdoor temperature MUST be lower than the condensing temperature. Otherwise, heat rejection cannot take place. In general, most manufacturers tend to engineer their HVAC systems to maintain a 15-30°F condensing split. Heat mode has its own set of challenges. For example, subcooling can be difficult to predict in heat mode. However, between 20-30°F of subcooling in heat mode is normal. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan talks a bit about the air side of the system. Understanding airflow is all about seeing the relationship between readings. We cover latent and sensible heat, relative humidity, wet and dry-bulb temperatures, and static pressure. Latent and sensible heat refer to heat that we can feel (sensible) or heat that contributes to a phase change and cannot be felt (latent). Both latent and sensible heat have a major impact on equipment sizing, especially in coastal regions and other areas where humidity is naturally high. When we attempt to control sensible and especially latent heat, we have to look at the airflow over the evaporator coil. When you run the blower more slowly, you pull more moisture (latent heat) at the expense of efficiency and capacity. Therefore, for peak capacity, efficiency, and sensible heat removal, you will want to max out the blower speed. Delta T (or air temperature split) is another important reading. Delta T is the temperature differential from the return to the supply. When you measure delta T with a dry-bulb thermometer, you will only get a sensible heat measurement. You need a wet-bulb temperature reading to account for humidity and latent heat changes. Relative humidity (RH) is the ratio of moisture in the air compared to the maximum at that temperature. Therefore, wet and dry-bulb temperatures are the same at 100% relative humidity. Static pressure is an indicator of airflow, but it isn't airflow. Static pressure is essentially resistance pressure that exerts itself on all surfaces. It is not the force of air flowing through the duct (that's velocity pressure). Also, consider adding a differential manometer to your toolbox. They make measuring TESP a breeze. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

In this first episode of a new series Justin talks about the calls he is doing before and after he does them, giving us a look inside the van of a senior HVAC tech.

In this episode of the HVAC School Podcast, we talk about some cool technologies and controversial tools. Joe Shearer joins us to talk about hard start kits. Some people believe that hard start kits are only suitable for one-time use, but Joe and Bryan believe that there's a lot more to it than that. If hard start kits are high-quality, then you could leave it on. However, if a unit has a hard-shutoff TXV, then it absolutely needs a hard start kit. Many techs are still hesitant about using hard start kits because they can damage the compressor if the relay doesn't take them out. Some techs feel similarly towards Stay Brite #8. You don't have to flow nitrogen with Stay Brite #8 solder, and some technicians (Bryan included) are suspicious about the quality of the work when you cut out those critical steps. So, many technicians prefer brazing, but Stay Brite #8 and brazing each have their benefits and drawbacks. At AHR, Bryan got a chance to speak with FasTest representatives about CoreMax valve cores. These large cores are great for commercial HVAC applications and help you achieve high flow during evacuation. Your typical core removal tools won't work, but CoreMax core removal tools exist, and the core assembly is also easy to replace. He also got to speak to a Packard representative about motor temperature ratings, especially on OEM vs. aftermarket motors and motor performance in various ambient conditions. Browning shared some information about their notch belts and the temperature ratings of those belts. Also, remember to check that the discharge temperature stays below 220°F. The discharge temperature can tell you a lot about your compressor and your chances of experiencing oil breakdown. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, Jeremy Smith comes on the podcast to talk about low-ambient controls, headmaster valves, charging, and condenser flooding. If our head pressure drops too much, we won't get enough of a pressure drop across the TXV. Pressures dictate the TXV function, so we need to make sure our systems give that valve what it needs to operate correctly. Three pressures operate a TXV: bulb pressure, spring pressure, and evaporator pressure. However, pressures throughout the system can also affect the pressures that act on a TXV. Condensers are sized for maximum heat rejection at the highest ambient temperatures a unit will experience. Low-ambient controls help get your liquid pressure up by effectively reducing the condenser's capacity. One common thing we can do is use a fan cycle; a pressure control can turn the fan on and off, but you can see large pressure swings. We can also use headmasters, which maintain head pressure by backing up liquid in the condenser; it fills the condenser with liquid and shifts some discharge gas to the receiver to maintain the receiver pressure. Headmasters are NOT adjustable in the field. When diagnosing headmasters, try to look for leaks first; Jeremy thinks many headmaster failures could have been misdiagnosed. Split condensers can shut off parts of themselves to reduce capacity, which can serve as another low-ambient control without bypassing discharge gas or wasting energy. You may also come across some adjustable controls that allow you to adjust your head pressure by setting receiver pressure and other similar values. Jeremy and Bryan also discuss: Balanced-port TXVs Fan cycling in air conditioning Using a clear sight glass to charge refrigeration units Headmaster part numbers Carrier Motormasters Parallel rack systems and remote condensers Inefficiency and bypassing discharge gas Read the companion tech tip HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bryan takes a break from the technical talk and tells a quick story about how two brothers fueled an industry and created an empire with raw sibling rivalry. Bryan co-owns a family business, and we understand that many people in this trade work with family, so we hope you'll enjoy this story. Many of us are competitive, and nobody enjoys failing. We especially try to avoid failing in front of our family members. However, the drive to succeed and avoid failure can sometimes get a bit out of hand. In the early twentieth century, two brothers named Adi and Rudy Dassler worked in their father's shoe business. Rudi was the more outgoing older brother; Adi was younger, quieter, and focused on making shoes. Business practices had changed as industrialization occurred across Europe, and many shoes were made in a factory instead of by hand. With all of the innovation going on at the turn of the century, both brothers realized that they, too, could own a factory. After serving in World War I, Adi began making shoes in his mother's laundry room. Rudi talked their parents into helping start up a shoe business. The brothers established their own athletic shoewear company, which became popular with help from the Modern Olympic Games. Adi approached Jesse Owens, a famous African-American track athlete from the United States, to wear his shoes in the Olympics. Jesse wore the shoes to victory, angering many Nazis. Rudi was the more ardent Nazi, and a rift started between the brothers. Rudi was arrested for war crimes during World War II, though historians suspect that Adi may have snitched on him. The sibling rivalry came to a head in 1948 when Rudi officially split from the company and formed Ruda. Adi formed Adidas, which was more successful than Ruda (now Puma). If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, we talk with Jeff Nieman about chillers and how they work. For those of you who primarily work in residential or light commercial HVAC, chillers may be unfamiliar at best and terrifying at worst. However, centrifugal chillers' parts are actually quite similar to those of HVAC units. They have an evaporator, compressor, condenser, metering device, and control system, just like the HVAC units we see every day. Jeff believes that breaking a chiller down into its parts is the easiest way to become comfortable with it. Chillers are used for comfort cooling and process cooling. In comfort cooling, chillers discharge cool water (44°F) to the building. From there, air blows over the water to cool the space. For process cooling, chilled water flows through machines that require constant cooling to operate correctly, such as laser-cutting machines and MRIs. As you can see, chillers simply absorb and reject heat, just like standard compression-refrigeration HVAC systems. However, unlike traditional compression-refrigeration units, chillers have an independent oil circuit. Preventive maintenance is a major part of chiller work. You can tell a lot by listening to a chiller and looking for oil or water on it. You also check superheat, subcooling, and water temperatures. Service calls also require technicians to engage their senses. Most issues deal with low water flow, building issues, and dirty strainers in the condenser water piping. Bryan and Jeff also discuss: Two-way and three-way valves Glycol and freeze protection Alarms (float switch, low evaporator pressure, high condenser pressure) Chiller troubleshooting Impellers and inlet guide vanes Suction in negative pressure Fan coils Chiller water Screw chillers Also, Bert and the Testo 770-3 make an appearance. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode, Bryan and Bert talk about properly stripping cables and leak detection best practices. Bert is a senior technician and self-proclaimed leak detection expert. As a slight aside, Bert CAN'T STAND when technicians strip wires. Basically, his advice is NOT to cut around the wires or use a razor knife. Leak detection starts when you walk up to a unit and confirm that the unit is low on refrigerant. Typically, you hook up gauges and check the five pillars. You will particularly check for low superheat and high subcool. However, your senses are also important during the confirmation process. Use your eyes before even grabbing a leak detector. You can typically spot corrosion on the line set, coil, or pipe fittings. Then, you can perform a bubble test to confirm the leak without a tool. Bert starts with coil and checks for oil spots. He then feels brazing joints for oil (even though that sounds a little suspicious). Most importantly, if Bert suspects a leak, he does his bubble test BEFORE pulling out the electronic leak detector. When Bert uses the leak detector, he turns it on and lets it stabilize for a little bit. He starts LOWER on the coil to get a hit and starts HIGHER to pinpoint the leak. And NEVER put your probe in water! New coils can be tricky. Although they CAN leak, it's improbable. If your leak detector gets a hit on a brand new evaporator coil, it could be caused by the chase. You MUST confirm that the leak is on the coil; it's not good enough to say that there is a leak without knowing exactly where the leak is coming from. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

n this episode, Bryan covers evacuation, recovery, and dehydration. Evacuation refers to putting a vacuum pump on the system and pulling it down. We use a few different measures of vacuum, including inches of mercury ("Hg) or microns (millionths of a meter of mercury). We use such small units to measure a vacuum that effectively boils off moisture in the system. You must pull the vacuum very close to a perfect vacuum. So, a measurement of 500 microns indicates that the vacuum is 500 microns of mercury above a perfect vacuum. Dehydration is a mere component (or result) of evacuation. If there is excess moisture in the system, it can freeze inside the system and cause blockages. It can also interact with oil and refrigerant inside the system to create an acid that ruins your unit. To get a proper vacuum, you have to pull down to 500 microns. You can go lower than that, if possible, but 500 microns is the industry standard. Remember that Schrader cores restrict your vacuum. Remove them with a proper core remover tool for a more effective evacuation. Larger hoses and better equipment won't make a difference if you leave those Schrader cores in. If you don't have Schraders, you probably have a service valve. Recovery removes refrigerant from a system under vacuum and puts it in a tank. We do recovery because we CANNOT vent refrigerant. As a best practice, when you connect your vacuum rig to the port, you can use a little bit of Nylog thread sealant to keep moisture and other contaminants out. Bryan also covers: Push/pull method Microns Vacuum pump oil Moisture contamination Vacuum restrictions Triple evacuation and sweeping nitrogen King valves/service valves De minimis As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

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. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode, Bryan talks to YouTube star Stephen Rardon about combustion analysis. In Florida, we mostly have A/C units and heat pumps. High-efficiency furnaces are not in our wheelhouse, but furnaces are more like A/C units than you would imagine. Stephen Rardon makes some excellent comparisons between the two. For example, you can get an idea of how an A/C system is running without checking superheat and subcooling. With a gas furnace, you can get an idea of how it's running without checking combustion. Of course, these are both general, and you lose out on knowing the specific parameters. In a sense, oxygen (O2) and carbon dioxide (CO2) in a high-efficiency furnace can be compared to superheat and subcool on an A/C system. Going even further, we could say that a furnace's stack temperature is equivalent to airflow. Stack temperature indicates if the system is moving enough air to pull the heat off the heat exchanger. If the furnace can't adequately heat the air, then we have to look at how it's moving air in the first place. Meter clocking is a bit controversial. There is an attitude that clocking meters doesn't matter, especially among old-school techs and ones who don't have a lot of experience clocking meters. However, it is a vital step for accurate combustion analysis. Knowing how many BTUs the system is dumping is a useful measurement, especially for diagnosis. You could compare it to a delta H reading on an A/C system; the number likely won't affect the outcome, but it helps you learn more about the system. Bryan and Stephen also discuss: Stephen's HVAC YouTube journey Gas furnaces Underrated readings Fancy diagnostic tools Follow Stephen HERE. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. For 6% off of tools go to HVACRschool.com/trutech offer code = getschooled Big thanks to Carrier & Carrier Enterprise for their generous support of HVAC School.

In this unedited episode of HVAC School, Bryan and Nathan talk about some basic rules for circuit board diagnosis. So, circuit boards are boards with circuits in them. They come in two types. The traditional printed variety contains switches, relays, and resistors. The other type contains silicon chips and uses logic and processing inside the boards. You may notice these in some high-end commercial systems (EMS), but we rarely see them in residential HVAC. The diagnostic challenges come in when technicians are unfamiliar with what's on the circuit board. It helps to break it down and look at one thing at a time. Yes, there are lots of wires and relays. You may not know what it does. Take your time and get to know where everything goes and what the components are doing. Techs often misdiagnose boards because they simply don't understand how it works, and many of them don't make the effort to understand it. It may help to look at the overall purpose of the board. For example, a defrost control simply initiates and terminates defrost. It controls the condenser fan, reversing valve, and heat strips, all of which have a function in the defrost process. If you have a short on the board (no-load path), you will see arcing somewhere. You would most likely see melting on the board if that were the case. If you have a board that has failed open, the switches are closed, and there is an input. However, the board doesn't travel through the time delay to bring on the contactor. Bryan and Nathan also cover: Isolation diagnosis Best practices Pulse-width modulation (PWM) "Ghost voltages" Jumper wires vs. meters for diagnosis Blown fuses As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

Benoit Mongeau comes on the podcast to talk about high-efficiency gas furnace basics and maintenance practices. When maintaining a high-efficiency gas furnace, you typically don't have to worry about cleanliness in the same way you'd worry about an oil furnace. However, condensate drains need regular cleaning. You'll want to look for cracked heat exchangers and pay attention to your manifold gas pressure. We also have to check the temperature rise, also sometimes called delta T. Bypass humidifiers will often affect your temperature split, so that's something you need to account for in cold, dry climates; hot air will go from the supply plenum to the return. (However, corrosion typically isn't a concern for bypass humidifiers.) Water is a product of combustion, so drainage is very important to gas furnaces. Manufacturers tend to recommend that most high-efficiency furnaces be built slightly pitched to aid condensate removal. Since the combustion air contains moisture, the condensate ends up being quite acidic; that condensate is really a mix of condensed combustion products. Combustion analysis is also an important part of maintenance. If your gas burns incompletely, the furnace will end up making deadly carbon monoxide, which is the main value we measure in combustion analysis. Typically, the carbon monoxide levels should stay below 100 PPM. You can do your combustion analysis anywhere in the flue pipe as long as you're past the inducer motor. (Note: the exhaust pipe should never be above the air intake.) A liquid petroleum (LP or propane) furnace differs from a gas furnace because it has different pressure needs. You may also have to add a restriction to the burners. Benoit and Bryan also discuss: Air intake drains "Condensing" gas furnaces Inducer motor types High vs mid-efficiency furnaces Excess air Low-fire vs. high-fire gas pressure and potential effects on combustion If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode of HVAC School, Bryan talks with Ulises Palacios about some cool technology. Ulises has become a technology expert through his many years of working with new tools. He has recently been involved in testing new technologies, and he has worked with Jim Bergmann. Cutting open a compressor is one of the most useful diagnostic tools you can use on a failed compressor. It is also an excellent way to learn more about your equipment. They help quite often with burnouts and mechanical failures. Although winding damage is an electrical issue, other mechanical failures cause winding damage and arcs. Copper plating is relatively common in compressors. However, it makes compressor failure even more likely, as copper can be easily corroded by acid. Copper in the bearing surfaces can corrode due to moisture, manufacturer additives, and industrial byproducts in the condensing unit. Additionally, POE oil mixes with moisture to make acid. Older mineral oil (MO) does not react with moisture to the same degree. The iManifold is an expensive but convenient and helpful piece of technology. It takes the information required for the five pillars of HVAC diagnosis. It saves you time on the job site and gives you all of the readings you need. You input the tonnage, SEER rating, and refrigerant to help with diagnosis. The iManifold also syncs up to an app on your phone. Thermal imaging is not just cool. Like the iManifold, thermal imaging can also be a helpful tool for diagnosis. It can be useful for duct inspections and locating restrictions. It also doesn't have the same accuracy concerns as infrared thermometers because it compares temperatures in an area. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode of HVAC School, Bryan covers the basics of heat pumps. Heat pumps are common technologies in Florida. They reverse the sequence of the typical refrigerant circuit: the indoor coil can become the condenser, and the outdoor coil can become the evaporator. Heat pumps can achieve that transition via a reversing valve, which changes the directions of the suction and discharge lines. They also have two metering devices. Reversing valves contain a solenoid (typically 24v) that rediverts the suction and discharge lines via shifting the slider with a pressure differential. Pilot tubes shift gas from one side of the slider to the other, which shifts it and triggers heat mode or cooling mode. Reversing valves are typically energized in cool mode (except for Ruud/Rheem reversing valves; they energize in heat mode). Defrosting is rarely necessary for us in Florida, but it can be a scary occurrence when we do need it. The outdoor coil can freeze over entirely when it gets cold enough due to Florida's high humidity. Hot gas goes through the coils during defrosting, and it may make alarming noises. Many Floridian heat pumps also use auxiliary heat strips to provide heat while the system defrosts. Many defrosts rely on set times and sensors to determine when to initiate and terminate defrost. (That is true of heat pumps AND most refrigeration systems.) Thermistors are common sensing technologies used in defrost. Join Bryan on this informative monologue about: Reversing valves Aux heat W and W2 Heat Pumps Defrost Checking refrigerant charge in heat mode Heat mode expansion valves Common heat pump considerations For a more detailed written explanation of heat pump reversing valves with pictures, check out this article. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan and Nathan have a banter-filled conversation about electrical components that confuse techs. If you are looking for a serious educational episode, we suggest you look elsewhere. Low-voltage circuits may confuse the new technician because the "common" terminology is far too common in the circuit. (See how confusing it sounds in everyday use? We don't have to say "common this," "common that," but we do.) Single-phase power can also be confounding for technicians. One phase of line voltage comes in, and it gets split when it enters the circuit. That is why we also call single-phase power "split-phase" power. Another perhaps surprising area of confusion is normally open (NO) and normally closed (NC) switches. Water metaphors could potentially contribute to the confusion, as shutting off the faucet seems analogous to "closing" a circuit, but it actually has the same effect as "opening" a switch. As instructors, we need to clarify that "open" and "closed" are different from doors, faucets, etc. "Open" means that there is no path, and "closed" means that there is a path. "Normally" merely indicates the state of the switches when nothing is happening. Sometimes, transformers can be difficult to understand. A transformer is an inductive load that alters voltage and "steps it down" to a secondary voltage. Loads are what "do something" in a circuit, like a light bulb or motor. Inductive loads are magnetic (motors and transformers), and resistive loads create heat (light bulbs and toasters). Inductive and resistive loads are perfect subjects for PG-13+ metaphors, as Nathan demonstrates. Join Nathan and Bryan on a vulgar learning adventure of bad metaphors as they discuss: Relays Sequencers Inductive loads Resistive loads Blower/heat interlock Transformers Contactors As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

This podcast is a high voltage A/C electrical class that Bryan gave to some of the Kalos apprentices. The high voltage journey begins with basic electrical theory. Basically, a difference in charge is needed for electrons to move and generate power. Motors, which are inductive loads, are the greatest users of power that we will encounter in the field. Inductive loads generate magnetism and utilize alternating current (AC) power. AC power is generated by a rotating magnetic field, and the direction of the current alternates. Comparatively, resistive loads generate light and heat, and direct current (DC) moves in one direction. Theoretically, we can use Ohm's law in the field to determine the voltage, amps, or resistance (ohms) without a meter, so long as we know two of the three values. However, we may not get an accurate measurement of ohms due to reactance on inductive loads. The windings you will encounter in the field include common, start, and run. (Remember: the same side that feeds start feeds run.) In a PSC motor, the start winding stays in the circuit the entire time. When you ohm the windings, you will notice that common has the lowest resistance, run has moderate resistance, and start has high resistance. (Common to run + common to start = run to start). Universally, capacitors contain a brown, black, white, and brown-and-white wire. You can wire a capacitor in two different ways; one uses three wires, and the other uses four. The three-wire method caps off the brown-and-white wire, leaving it unused. Join Bryan and the apprentices in their high voltage class as they cover: Basic Electrical Theory Potential Difference Basic Capacitance Motor Lead identification Different motor type Motor Direction Proper Wiring MOCP and MCA As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan talks to Justin Skinner about the standard gas furnace sequence of operation. Regardless of the furnace type, it all begins with a heat call on W... Then, the furnace checks the safeties to make sure ignition is possible and safe. If all systems are a go, the inducer motor comes on and clears a path for the exhaust. The furnace then proves that the path for the flue is clear, and a pressure switch closes upon sensing a pressure differential. The miracle of ignition comes next. There are a few different types of ignition, including hot-surface, intermittent spark, and standing pilot. Once the furnace opens the burner, it has to prove the flame. Proving flame is somewhat similar to proving the flue path. A flame sensing rod creates a potential, and it determines if a flame is present by picking up microamps of current to ground. We're merely scratching the surface here, but the bottom line is that the furnace does a lot of checking and proving throughout the startup procedure. Above all else, remember to check the fault code if the sequence of operation fails to complete. The absolute WORST thing you can do is restart the furnace, take the door off, or turn the furnace off. You lose a major troubleshooting clue. Join Bryan and Justin as they talk about these furnace sequence topics: Low Voltage Wiring Boilers Forced and Natural Draft Flame rectification Cleaning Flame Sensors Gas Pool Heat Silicon Nitride and Silicon Carbide Hot Surface and Intermittent Pilot As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

Central Florida techs know the Southern winter all too well. Let's face it. It doesn't get super cold here regularly, but when it does, EVERYONE FREAKS. We get an abundance of service calls for unpleasant but not truly problematic conditions when people use their heaters. When people first turn on their heat, they can get a nasty surprise: a horrible dirty-sock smell and sometimes a shrieking smoke alarm. These are normal, albeit unpleasant, and do not require a service call. Another unpleasant or alarming occurrence is when a heat pump unit goes into defrost mode. Defrost mode shifts the unit into cooling mode, which may make some cold air come out of the vents. On top of that, customers may hear an awful noise and feel concerned when they see steam coming out of their unit! Pool heaters are a completely different animal in a Southern Winter, and they are often made quite poorly. You may come across gas pool heaters, propane pool heaters, heat pump pool heaters, and even solar ones. Each type has its own set of maintenance needs and varying degrees of effectiveness. When working with them, the goal is to set establish realistic expectations and explain best practices to the customer to minimize those frustrating service calls. In this episode, we talk about: Burning off heat strips Heat pump defrost mode Gas pool heater Heat pump pool heaters The thermodynamic principles of heat pump heating Defining BTUs Liquid petroleum (propane) vs. natural gas And much more... This podcast is in an unedited "meeting format" and is not usually the type of thing you will get on HVAC school, but I still think it may benefit junior techs and office staff. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode of the HVAC School Podcast, Bryan talks with Jeremy Smith about refrigeration tips, terms and processes. They also cover the similarities and differences between A/C and refrigeration. Being on-call as an A/C tech is not all that different from being on-call as a refrigeration tech. Similarly, the principles of heat transfer don't change between the A/C and refrigeration trades. Both trades follow the same basic rules, but all of those valves, adjustments, and tuning on rack refrigeration systems may make an A/C tech's head spin. Refrigeration techs may come across glycol chillers, rack refrigerators with several refrigerant circuits on a single piece of equipment, or piping that has been warped by hot gas defrost. There is also a greater emphasis on regulating suction pressure rather than merely measuring it, and refrigeration techs use EPR valves to help control that pressure. Each refrigerated case also has its own expansion valve. Jeremy also covers the complexity of defrost. In A/C, defrost could be as simple as shutting a unit off for a period of time. Defrost is more critical in low-temperature applications, though hot gas defrost may damage pipes and make them prone to leaks. Electric defrost typically has a lower potential to cause damage. Also, subcooling is less of a big deal in refrigeration. Sight glasses and receivers make subcooling less vital than it is in HVAC. Join Bryan and Jeremy as they discuss: Reznor startup Being on call in the refrigeration world Differences and similarities between rack refrigeration and A/C Hot gas and electric defrost Glycol refrigeration systems Subcool and superheat Refrigeration TXV settings EPR valves and their settings Rack manifold pressure And many more refrigeration tips... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode of the HVAC School Podcast, Bryan talks with Tim Bagnall about flowing nitrogen. Many techs don't flow nitrogen. Some may say that it is overkill, but it has been shown that flowing nitrogen displaces oxygen while brazing and prevents harmful scale from forming on the copper. Scale is very problematic, and it will likely ruin your copper lines if you keep those lines open to air. (The jury is still out as to whether climate/geography affect scale formation, though.) There are many different intensities for flowing nitrogen, particularly high-pressure purging and low-pressure flowing (2-5 SCFM). You may also have heard that you should flow nitrogen at 1.5-3 PSI, though SCFM is the preferred unit. Some best practices for flowing nitrogen while brazing include using wet towels or heat-resistant putty on the service ports, removing the Schrader cores, removing the TXV sensing bulb before brazing, and watching your torch control so that you do not overheat the metal. Join us today as we discuss the following: The proper tools and flow settings for brazing How the pressures should be set to SCFM and not PSI The possibility that geography may contribute to scale How to flow nitrogen in a practical way And much more... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode, Bryan goes back over the basics and stresses the importance of diagnosing the whole system. I'll cut to the chase: inspection is NOT overrated. Inspections help you become more familiar with HVAC systems and can help you catch on to minor issues before they spiral out of control. Check air filters, check the charge, check the evaporator coil... does the inspection checklist ever end? Whether you see crunchy brown contactors or oil on the lines, none of those issues are too small to warrant investigation and repair. Those may not seem worth the hassle, but a leak or low charge can negatively impact the A/C function over time, leaving you with unhappy customers. Checking everything may seem a little over-the-top, but it really is in your customers' best interest. The same goes for mundane procedures like cleaning out drains. We also have our controversial practice of the day: you don't NEED to remove a slant coil for cleaning all the time. Cleaning it in place is A-okay. Some of the system procedures I'll discuss include: Checking the charge completely Superheat and subcool Checking the evaporator coil Inspecting the filter Looking for wire rubouts Checking the drain line and drain pan Checking capacitors and contactors And much more... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.