HVAC School - For Techs, By Techs

In this episode, Bryan and Roman dive deep into the world of Variable Refrigerant Flow (VRF) systems, focusing on the persistent issue of compressor failures. VRF technology has evolved, and it has seen a major rise in the North American market since the early 2010s. Roman shares his passion for VRF, tracing its origins back to 1982 and explaining how it earned the nickname “chiller killer” by replacing traditional chiller systems in large facilities like hotels, churches, and schools. However, with this rapid adoption came a troubling reputation: VRF systems became notorious for frequent compressor failures, prompting some institutions to revert to older technologies. There are three primary causes of compressor failure in VRF systems: oil lubrication issues, liquid refrigerant return, and electrical failures. VRF compressors are shipped with excess oil to account for the system’s extensive piping and multiple indoor units, but improper refrigerant charge—either overcharging or undercharging—can disrupt oil return and lead to gradual compressor death. They emphasize the importance of correct installation, accurate charge calculation, and diligent maintenance. Bryan adds that measuring discharge superheat is a key diagnostic tool: high discharge superheat with normal suction superheat signals poor lubrication and impending failure. The discussion then shifts to the dangers of liquid refrigerant returning to the compressor. Even small amounts can wash oil off the scroll plates, leading to metal-on-metal contact, galling, and eventual mechanical breakdown. Roman details the difference between high-pressure shell and low-pressure shell compressors, noting that VRF systems are more susceptible to operational flood back, which can cause elevated amp draws and catastrophic failure. They also highlight the role of contamination—such as copper shavings or sand from installation—which can damage expansion valves and lead to chronic flood back issues. Maintenance, including regular oil analysis and monitoring of expansion valve performance, is crucial for long-term reliability. Finally, the episode covers electrical failures, often the result of underlying mechanical issues rather than true electrical faults. The hosts advocate for using insulation resistance testing (megohmmeters) as a maintenance tool to track winding degradation over time. They stress that proper cleanup after a compressor failure is vital, recommending temporary filter dryers and oil analysis to mitigate contamination. The conversation closes with practical advice: always investigate the root cause of a compressor failure, communicate findings with clients, and prioritize best practices in installation and service to prevent repeat issues. Topics Covered in This Episode: The history and rise of VRF technology in North America Why VRF systems earned the nickname “chiller killer” The three primary causes of VRF compressor failure: Oil lubrication issues (overcharge/undercharge, oil return) Liquid refrigerant return (flood back, expansion valve failures) Electrical failures (mechanical causes, insulation degradation) Diagnostic techniques: discharge superheat, suction superheat, amp draw analysis The impact of installation practices and system contamination Maintenance best practices: oil analysis, filter dryers, insulation resistance testing The importance of root cause analysis after compressor failures Resources for ongoing VRF education: VRF Tech Talk podcast, Facebook group, and Roman’s YouTube channel 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 some no-serve situations he's encountered as a technician and HVAC business owner. He also talks about situations that may be unpleasant but aren't quite no-serve situations. Some common and obvious no-serve situations are when a client threatens a technician, especially with lawsuits, bad reviews, or even bodily harm. However, some clients are just naturally defensive, so we want to be careful and give people a chance if they're angry and might just need to calm down. Unrealistic expectations can also cause no-serve situations. Some complaints are tricky to deal with but can be solved, but other problems are impossible to solve. We have every right not to serve clients who have problems that don't have realistic solutions (such as wanting a thermostat that doesn't make a clicking noise at all). In those cases, Kalos usually gives some degree of a refund and agrees not to do business with the customer again. Dirtiness of the living space can also be a no-serve situation. Unless a home is dangerously filthy (e.g., it can cause a respiratory disease) or the equipment is not accessible, we can serve them. Even if the home is filthy or the equipment is inaccessible, we can ask the owner to clean up and return to serve them. On the other side of the coin, hypochondriacs can be a challenge to deal with, but no-serve situations are rare; we can take precautions, including more thorough testing and hold-harmless agreements. Other no-serve situations are people who don't pay, people who regularly pay extremely late, customers who aren't the owner (such as tenants or family members), and clients who try to drag you into drama with other contractors. 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 informative HVAC podcast episode, Bryan and Bert dive deep into the complex world of locked and internal overload compressors, focusing specifically on single-phase residential units. The discussion begins with Bert explaining one of the most common challenges technicians face: diagnosing a locked compressor. He describes how compressors that are locked will typically run for only a second before overheating and stopping, creating a cycle that can be difficult to detect if technicians aren't carefully monitoring at the right moment. The hosts share personal experiences and practical diagnostic techniques, with Bert recounting how he once simulated a locked compressor by cutting the start winding wire and concealing it beneath other wires and zip ties. This demonstration highlights the importance of thorough inspection, including checking terminal connections. Bryan shares a story from his early career when he mistakenly condemned a compressor with damaged terminals, not knowing about terminal repair kits - a candid moment that illustrates how even experienced technicians continue to learn throughout their careers. A significant portion of the podcast is dedicated to explaining the electrical fundamentals of compressor operation, including an enlightening discussion about start windings, run windings, and common connections. Bryan passionately clarifies misconceptions about current flow through these different windings, explaining that the start winding actually has consistently lower amperage due to its connection through a capacitor. The hosts also detail the critical differences between a compressor that's overheating versus one that's truly locked, emphasizing that the physical temperature of the compressor often provides the key diagnostic clue. Key Topics Covered: · How to identify a locked compressor versus one that's out on internal overload · The importance of checking terminal connections and wire continuity · Why compressors that are truly locked don't have time to physically overheat · Common causes of compressor overheating: condenser fan failure, refrigerant issues, airflow problems · The proper diagnostic method for catching a locked compressor "in the act" · The mechanics of start windings versus run windings and their amperage differences · When and how to use hard start kits appropriately (and why they shouldn't be used universally) · How to communicate with customers when diagnosing compressor issues · The role of crankcase heaters in preventing flooded starts · Terminal repair techniques and when they're appropriate 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 covers some unique electrical cases: when 0v isn't safe. When you measure voltage, you're finding out the electrical potential between two points. Just because there is 0v between one point and another doesn't mean there will be 0v between those points and other points. Non-contact voltage detectors are good tools that measure the flux from the wiring, but they have their limitations. A common mistake is measuring voltage across a switch. When you measure 0v across the switch, that could mean there is 0 potential to ground, neutral, or the other leg, but it could also represent a closed switch where power is actively being passed. You need to measure voltage across a load or with neutral as the other point. You will also measure 0v when one of the legs of 240v power (with a two-pole breaker) stops making contact. You'll measure 0v between the legs, but that's because one of the legs is open. There may still be a complete path on the other leg; therefore, you will want to check for voltage between each leg and ground, not leg to leg. This condition is particularly common in pool heaters. In some cases, the meter isn't working and will read 0 when it's set to another unit setting, isn't on (if an analog), or the leads aren't fully plugged in. Check to make sure your meter is on the correct setting, is in proper working order, and has a good connection to the leads. 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 episode, Bryan and Bert dive into the often misunderstood world of compressor testing, focusing on common mistakes technicians make when using ohmmeters, compressor testers, and megohm meters. The conversation highlights how diagnostic errors can lead to unnecessarily condemned compressors and wasted time and resources. The hosts begin by discussing fundamental concepts like the difference between "open" and "short" conditions, emphasizing that a path doesn't necessarily indicate a short circuit—it simply means there's a low-resistance path. They explore how many technicians get confused when testing terminals, mistakenly thinking that normal winding-to-winding measurements indicate a problem. Through practical examples from their field experience, they illustrate why understanding normal readings is crucial before taking any measurement. A significant portion of the discussion centers on proper testing techniques for scroll compressors, which often show different measurements to ground compared to other compressor types due to their design, with windings submerged in refrigerant and oil. Bryan and Bert explain why standard motor testers can lead to false diagnoses when they indicate "bad" at threshold levels like 20 megohms—a reading that would be normal for many functional scroll compressors. They recommend proper megohm meters calibrated to appropriate voltage levels for accurate testing. Key Topics Covered: 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 what the ambient rating means on a motor. These ratings can be found on both condensing fan motors and blower motors. They have Cs in their rating, which represents the maximum ambient temperature the motor can handle in degrees Celsius (like 40C or 60C). Heat and overvoltage kill motors, and motors with higher ratings can withstand higher temperatures and last longer in hot conditions. Be careful not to confuse this rating with the insulation class (which is classed by letters and corresponds to temperature limits). You could have a condition where you exceed the insulation's rating but not the ambient rating. Air over operations (especially in the case of TEAO motors - totally enclosed air over motors) also play a role. The airflow helps cool the motor, and airflow restrictions like dirt and soil can create conditions that cause the motor to exceed its rating. Motor bearings also matter. Ball bearings tend to last longer and withstand higher temperatures than sleeve bearings, but they are noisier. Many motors use sleeve bearings, and replacing a sleeve bearing motor with a motor that uses ball bearings may negatively affect the homeowner's comfort due to the noise, so that's a conversation you'll want to have with the customer and set realistic expectations. 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 episode of the HVAC School podcast, host Bryan discusses superheat with guest JD, who recently co-authored an article on the topic with Ty Branaman. The conversation explores the often misunderstood concept of superheat, its importance in HVAC diagnostics, and common misconceptions technicians have when measuring and interpreting it. Bryan begins by sharing how superheat was initially taught to technicians in the late 1990s and early 2000s, primarily as a method for charging fixed metering device systems. He explains how this limited view led to problems, as technicians would often add or remove refrigerant based solely on superheat readings without considering other system factors or giving the system time to stabilize. JD points out how the industry shifted when TXVs (Thermostatic Expansion Valves) became standard, with many technicians abandoning superheat measurements altogether in favor of subcooling measurements, missing crucial diagnostic information in the process. The discussion then evolves into a more sophisticated understanding of superheat as an indicator of evaporator coil "fullness." Bryan explains that lower superheat indicates a fuller evaporator coil, while higher superheat suggests a starved coil. They discuss the importance of measuring superheat in the correct location, noting that TXVs control superheat at the evaporator outlet, not at the condensing unit where technicians often measure. This misunderstanding leads to many incorrect diagnoses of "bad TXVs" when the real issues might be related to airflow, heat pickup in line sets, or other factors. Both experts emphasize the value of measuring superheat both inside at the evaporator outlet and outside at the condensing unit to get a complete picture of system operation. Key Topics Covered: JD and Ty's superheat tech tip and worksheet: https://hvacrschool.com/solving-superheat/ 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, Bryan talks about how to deal with too much at work and in life. He gives some practical tips to help you when you feel overwhelmed. One of the best ways to get ahead is to wake up early, exercise, get sunlight, stay hydrated, eat healthy, and get enough sleep. Taking care of yourself and giving yourself ample opportunities to set your mind and body up for success can ensure that you have the energy to tackle the challenges at work and in other areas of your life. When you're in the middle of an overwhelming mix of tasks, it helps to take a small break and take some deep breaths. Some people take smoke breaks. Once you have an opportunity to step back and clear your head, try to document all of the things you need to do. You can use a Google Doc with the help of ChatGPT to lay everything out. Once you have all of your tasks in front of you, pick 3-5 things that must get done today and then use your calendar, silence your notifications, and use all the tools at your disposal to focus on those things. Perfectionism and people-pleasing can also get in the way of achieving all of your tasks. You have to be able to accept work that isn't perfect and say no to meetings or unnecessary tasks. You can use tools like Loom to document quick notes instead of holding a meeting. When you can't avoid meetings, try to batch them all at once. Batching, delegating, and automating tasks also come in handy, especially before tasks pile up and spiral out of control. 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

Bryan from HVAC School interviews JD Kelly, known as "student of HVAC" on Instagram, about Delta T measurements in HVAC systems. This episode dives into the fundamentals of Delta T, common misconceptions, and proper measurement techniques. JD explains that Delta T is simply a temperature difference between two points of the same medium, which is often misunderstood in the industry. Many technicians are taught to measure between return grills and supply registers, but this approach can lead to inaccurate readings due to external factors like duct leakage or heat gain from attics. The proper measurement should be taken directly at the equipment to evaluate how the evaporator coil is performing. Humidity plays a significant role in Delta T measurements, which JD discovered when researching the fundamentals. Bryan elaborates on this point, explaining that in high-humidity environments (like Florida), more energy goes toward removing moisture (latent heat) rather than cooling the air (sensible heat), resulting in lower Delta T readings. This is why a newly repaired unit in a humid house might initially show lower readings but improve as the home dries out. The discussion highlights why the common "20-degree Delta T" rule of thumb isn't universally applicable and requires context. Key Topics Covered: JD's Delta T tech tip: https://hvacrschool.com/solving-delta-t/ 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 fire sprinklers and how to avoid setting them off on job sites. Fire sprinklers have an element in the center that expands when exposed to heat (like a TXV sensing bulb) and breaks the glass. When the glass breaks, the fire sprinkler starts pouring out water. In some cases, fire sprinklers are linked to a larger fire suppression system in which several may go off at once, but most of the time, only a single fire sprinkler will go off if bumped or exposed to heat. If you're using torches or doing any form of hot work in a closet or other location with a fire sprinkler, make sure to keep torches away from the heat-sensitive bulb or at least cover the sprinkler with a wet rag (and follow your company's guidelines). Blunt force is another possible issue, so we want to avoid hitting the sprinklers with lifts, ladders, or building materials like studs. Keep clearances in mind, and watch out for your colleagues. You can get some specialty-built cages to protect the sprinklers, but awareness is one of the best ways to protect fire sprinklers. If possible, make sure signage is posted or that you alert other people in the area about the fire sprinklers. If the fire sprinkler does go off, make sure you can quickly reach the person(s) who can access the fire shutoff or direct you to the fire shutoff. While fire sprinklers won't pose much of a personal safety hazard, property damage is a major concern. Training and awareness are the keys to preventing property damage due to fire sprinklers. 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 engaging session, David Richardson breaks down the concept of high-performance HVAC, offering a clear roadmap for industry professionals looking to elevate their craft. Richardson argues that the HVAC industry has long been focused on equipment rather than complete systems, leading to widespread inefficiencies. The average system delivers only about 57% of its rated capacity into buildings, while even code-approved systems barely reach 63%. By implementing high-performance HVAC principles, contractors can achieve up to 88% efficiency while improving safety, health, comfort, and energy performance. Richardson presents a practical framework using the acronym "PATH" - Pressure, Airflow, Temperature, and Heat (BTUs) - as a step-by-step approach to implementing high-performance HVAC. He emphasizes starting with static pressure testing, which he calls "the foundation of airflow" and one of the most misunderstood principles in the industry. Just as doctors check blood pressure as a vital sign during every visit, Richardson advocates for measuring static pressure on every call, or at minimum, when encountering "red flag" issues like repeated equipment failures. From there, professionals can progress to measuring airflow, temperature, and finally BTU delivery to create complete system diagnostics. The presentation offers a journey-based approach, acknowledging that implementation takes time and requires breaking old habits. Richardson introduces the "one degree principle," suggesting that change happens incrementally, with small improvements eventually leading to breakthrough moments. He urges contractors to apply this methodology not just to equipment, but to extend testing into duct systems and even the building envelope. By making these changes visible through measurement, contractors can prove value to themselves, their teams, and ultimately their customers, transforming the way HVAC work is perceived and delivered. Key Topics Covered: 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 episode of the HVAC School Podcast, host Bryan sits down with Phil, the executive electrical team leader at Kalos who has transitioned into the world of estimating. Phil shares his extensive background in electrical work dating back to 1994, from his high school electrical elective to running his own business for eight years before joining Kalos and eventually establishing their estimation department. The conversation delves deep into the fundamentals of estimating in the trades, contrasting traditional qualitative approaches with more rigorous quantitative methods. Phil emphasizes that good estimating is about "finding the truth" - understanding the actual costs of materials and labor for a project. They discuss how traditional estimating often relies on heuristics and past experiences with similar jobs, while more detailed estimating involves comprehensive takeoffs and assembly-based counting. The pair explores how estimation isn't just about producing a final number but should provide valuable information that transfers to the production phase. A highlight of the episode is Phil's introduction of his self-developed estimating software called Unity Build. He explains how his interest in AI technologies led him to learn programming and eventually create this cloud-based solution that integrates AI assistance while maintaining the fundamental tools needed for thorough estimating. The software allows for collaboration between team members, is entirely browser-based, requiring no downloads, and is priced at $125 per month per seat. Bryan emphasizes that this is Phil's own business venture that he's taken an interest in, and they both stress that potential users should buy it for what it currently offers, not future promises, though they are committed to continuous improvement. Topics Covered: Check out Unity Build Estimation at https://unitybuildestimation.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 short podcast, Bryan answers a listener-submitted question about Nylog, oil, and where you put them when you're making flares. Nylog is a thickened refrigerant oil (which is either POE for Nylog Blue or mineral oil for Nylog Red), and it's miscible with the refrigerant and moves with it through the circuit. You don't want to put excess Nylog on valves, but a small amount won't do harm. There are a lot of concerns about Nylog voiding the warranty, but it doesn't actually do that because it's nearly impossible to prove that Nylog caused the issue. Like oil, Nylog helps connections fit together (even threaded connections) and prevents galling. However, oil and Nylog also reduce friction, which will affect your torque specs when you use a torque wrench to tighten a connection. You don't need to tighten it as much, as you risk overtightening otherwise. When you apply Nylog, put a little bit on the front and back face of a flare (and the cone of the flaring block if you wish). You can put a small bead on the threads, but it's not an issue as long as you stay aware of your adjusted torque specs (low range). In our experience at Kalos Services, Nylog is particularly useful under vacuum and has helped us make high-quality flares that last a long time. Remember: Nylog is NOT leak lock, and it's not a traditional thread sealant. 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 episode of the HVAC School podcast, Bryan and Jim discuss strategies for growing an HVAC business, focusing on the importance of maintenance contracts, consistent service, and effective branding. Drawing from Jim's 15 years of experience running a successful HVAC company in California, they explore how maintenance contracts not only provide consistent revenue but also create valuable training opportunities for technicians. The conversation emphasizes that maintenance contracts are fundamental to building company value. Jim shares that when he sold his business, the number of maintenance contracts was a key valuation metric. These contracts tie customers to your company, provide consistent work during shoulder seasons, and offer technicians crucial repetitive practice with equipment. Bryan adds that maintenance provides technicians with opportunities to observe normal equipment operation repeatedly, which builds troubleshooting skills through pattern recognition. Both hosts stress the importance of consistency in growing a business. They note that large, successful HVAC companies aren't always the most technically excellent, but they deliver consistent service that customers can rely on. Jim introduces the marketing concept of "TOMA" (Top Of Mind Awareness), sharing how he used branded coffee bags as thank-you gifts to keep his company in customers' minds even after service calls were completed. The discussion concludes with an examination of White Rogers' contractor branding program, which allows HVAC companies to put their name and logo on thermostats, creating another touchpoint for customer awareness. Key topics covered: Get contractor branding on your Sensi thermostats today at https://hvacrschool.com/contractor-branding. 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 answers a listener-submitted question about oversized evaporator coils, particularly when they're half a ton or a full ton larger than the condenser. The expanded performance data contains the information that'll tell you whether the coil is right for the system. However, when it comes to the specific issue of oversizing, there is a common misconception that coil size affects the saturated suction temperature. The truth is that they're not related; you could fully insulate different-sized coils and move the same amount of refrigerant, but they will behave similarly. The saturated suction temperature (suction pressure, evap temperature) is driven by the heat entering the system. Coils are designed to handle refrigerant flow rates and airflows, so having a lower airflow over a large coil allows for greater cooling due to the bigger surface area, lower bypass factor, and dwell time. When more heat enters the evaporator coil, the saturated suction temperature increases, but some of that heat enters as latent heat and helps with dehumidification. However, a larger coil also takes longer to get colder, and the superheat settings become more important. You have to be careful with lower face velocities across the evaporator coil, as laminar flow isn't as good at transferring heat as turbulent flow. That is one of the limitations of using a larger coil with lower airflow. If the expanded performance data has a rated match for a larger coil, then that same data will also contain information about the required airflow. Testing in and testing out is also important. 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 episode of the HVAC School podcast, host Bryan sits down with building science expert Allison Bailes to dive deep into the world of Energy Recovery Ventilators (ERVs). The conversation explores the critical role of ventilation in modern homes, highlighting how ERVs have become an essential component of maintaining indoor air quality and energy efficiency. Bailes breaks down the technical nuances of ERVs, explaining how these systems not only bring fresh air into a home but do so while recovering both temperature and moisture energy. The discussion goes beyond simply explaining what an ERV is, delving into the practical considerations of ventilation strategies. Bailes shares personal experiences, including challenges he faced with over-ventilation in his own home, which led to extremely dry indoor conditions. The podcast explores the complex balance of bringing outdoor air inside while managing humidity, temperature, and air quality. Listeners gain insights into why simply bringing in outdoor air isn't always the best solution, especially in climates with extreme humidity or air quality challenges. Throughout the episode, Bailes and Bryan emphasize the importance of thoughtful ventilation design. They discuss the evolution of home construction, noting how increasingly airtight buildings have made proper ventilation more crucial than ever. The conversation touches on key considerations for selecting and implementing ERVs, including motor efficiency, boost capabilities, filtration, and the impact of outdoor air conditions. The experts provide practical advice for contractors, technicians, and homeowners looking to improve their understanding of indoor air management. Key Topics Covered: Resources Mentioned: energyvanguard.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 short podcast episode, Bryan answers a listener-submitted question asking whether you can use another surge protector at the disconnect panel with an ICM 493 already in place. Using multiple surge protectors in the configuration described does NOT count as daisy-chaining. Surge protectors with MOVs (metal oxide varistors) shunt current from high voltage to ground by reducing their resistance. MOVs are sacrificial, so they wear out over time. Surge protectors don't last forever, so installing multiple is a fine idea. You can have whole-home surge protection with additional surge protectors positioned at the appliances/electronics. While it can be done and doesn't hurt anything, it's not the most cost-effective solution. When you install a surge protector, wire it in parallel with the circuit to ground. It should be wired properly with the shortest possible path to ground. In any case, many surge protectors won't hold up against direct lightning strikes, but they will protect the equipment from power surges after power comes back on or constant overvoltage. Our company, Kalos Services, now uses DITEK's Kool Guard 2 as our surge protector and voltage monitor of choice. They also provide warranties for their products, which have come in handy for customers. Learn more about the DITEK Kool Guard 2 at https://www.diteksurgeprotection.com/product-series/intelligent-voltage-monitoring/. 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 podcast episode, HVAC professionals Chris Hughes and Adam Mufich discuss the intricate challenges technicians face when commissioning modern inverter-based heating and cooling systems. Unlike traditional single-stage or two-stage HVAC equipment, inverter systems introduce a new level of complexity that can leave even experienced technicians feeling uncertain about proper installation and startup procedures. The presentation highlights a fundamental shift in how HVAC systems operate, moving from straightforward single-stage systems to sophisticated inverter-based technologies that modulate compressor, fan, and refrigerant flow dynamically. This technological evolution creates significant challenges for technicians, who previously could rely on simple, consistent commissioning processes. The speakers emphasize that modern inverter systems require a much more nuanced approach, with specific temperature ranges, wait times, and verification methods that are not always clearly documented in manufacturer manuals. Recognizing the industry-wide need for clarity, Chris and Adam have developed a comprehensive spreadsheet resource that consolidates commissioning information across multiple HVAC brands. Their goal is to empower technicians by providing accessible, standardized guidance for working with these complex systems. By sharing their research and encouraging collaboration, they aim to address what they see as a critical gap in manufacturer support and technical documentation. The podcast serves as both an educational resource and a call to action for HVAC professionals and manufacturers alike. Chris and Adam argue that the industry needs more transparency, better documentation, and a collective effort to standardize inverter system commissioning practices. Their work represents a significant step towards demystifying these advanced HVAC technologies and ensuring that technicians can confidently and effectively install and service modern heating and cooling equipment. Key Topics Covered: 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, Roman Baugh takes over the HVAC School podcast to answer a listener-submitted question about VRF (or VRV) system evacuation. Evacuation is a critical step of making repairs on VRF systems, which are very diverse and versatile but require a high level of understanding. VRF systems have multiple indoor units per outdoor unit, and they achieve that with the help of several components and accessories down the refrigerant line that can pose issues in evacuation and pressure testing. In heat recovery units, some manufacturers use solenoid valves (or even electronic expansion valves) in branch selector boxes or branch collector boxes. These valves act as little traffic guards, and the system needs to be put in its refrigerant recovery or vacuuming mode. If not, then you won't be able to evacuate all of the refrigerant and non-condensables from the system. Even if the system passes a decay test, contamination is a major concern when the system starts up and the valves open (due to nitrogen and oxygen mixing with pure refrigerant being put into the system). You can trust and verify that the system is in its proper operating mode at the thermostat to ensure that the valves are open 100% and ready for evacuation or pressure testing. Failure to do so not only poses a contamination risk but likely won't maintain its pressure during the pressure test. Assumption or trust alone is not enough. Heat pumps only have two lines, and the vacuum pulls from both sides of the valve. There's less of an issue because there are no branch selector or collector boxes, but it's still good to ensure that the valves are responding and communicating. 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 podcast episode is of Bryan's session from the HVAC School Symposium, "10 Things I've Learned in the Last 10 Years." Delivered as HVAC School approaches its 10-year milestone and Kalos hits 20 years, Bryan blends technical know-how with personal stories, revealing how his “expertise” is a product of constant learning—often from the very audience he’s addressing. Bryan’s presentation weaves together practical HVAC lessons and relatable anecdotes, offering a glimpse into his growth as a technician, educator, and leader. He tackles wire sizing versus breaker sizing, debunking outdated myths tied to the National Electrical Code and sharing tales of sparring with inspectors over code-compliant innovations. On vent sweating and duct leakage, he provides actionable fixes—like sealing boots and tackling attic moisture—while urging techs to look beyond bandaids. Bryan also dives into coil corrosion, distinguishing formicary from galvanic causes and advocating for field-driven research over manufacturer spin. His interactive style shines as he pauses for audience questions, fostering a dynamic exchange where attendees refine his insights. The talk balances technical depth with human wisdom, spotlighting patience, joy, and consistency as cornerstones of his journey. Bryan recounts Eureka moments—like unraveling why high-latent markets defy evaporator temperature expectations—and credits mentors like Jim Bergmann and peers like Jordan Cummings for sharpening his perspective. He wraps up with a personal touch, addressing work-life balance as a father of 10 and business owner, advocating for mutual sacrifice with family over unilateral trade-offs. Topics Covered: Wire Sizing vs. Breaker Sizing: Debunks NEC myths and shares strategies for navigating inspector challenges. Vent Sweating Solutions: Offers practical fixes like sealing boots and managing attic moisture sources. Evaporator Temperature in High-Latent Markets: Explains unexpected suction pressure behavior with lower airflow. Control Layers in Ducts and Walls: Clarifies roles of vapor, air, and thermal barriers in system design. Formicary vs. Galvanic Corrosion: Differentiates coil leak causes, highlighting VOCs and flux issues. Low-Level CO Monitoring: Stresses its importance for safety in homes with combustion appliances. Duct Leakage: Links leaks to moisture and pressure woes, with visual diagnostic tips. Filtration Importance: Pushes for larger, sealed filters over inadequate factory setups. Compression Ratio and Dehumidification: Explores why ductless/inverter systems falter at moisture removal. Personal Growth and Joy: Ties patience, consistency, and community to a rewarding career. Work-Life Balance: Shares lessons on balancing family and work through shared sacrifice. 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