In this short podcast episode, Bryan covers some basics on bi-metal and magnetic switches. Bi-metal switches are made of two dissimilar metals that are bonded together and are often integrated into motors. When the temperature changes, the metals bend. In an overload circuit, they're designed to bend and open the circuit in an overheat condition. Mercury thermostats also use these; they have a bulb attached to a bi-metallic coil, which causes it to wind or unwind when heated or cooled. Fan limit switches also use bi-metallic coils. Bi-metallic discs also exist, and they snap open to make or break a circuit. Bi-metallic switches have a time delay and often auto-reset (with exceptions like rollout switches on furnaces), which is advantageous in some applications. However, they're also affected by the ambient temperature and are more likely to trip in warm weather and less likely to trip in cold weather. Nuisance trips are more common than in magnetic switches, and they may weld themselves shut and fail closed (though failing open is relatively common as well).  Magnetic switches are usually more external to the equipment or parts they're protecting (such as in the contactor or starter assembly instead of inside a motor itself). These switches are also more instantaneous and are better for mission-critical applications. These also respond to amperage and aren't affected by ambient temperature. They're more likely to fail open than closed. Compared to bi-metallic technology, magnetic switches trip faster and are better for sudden issues rather than long-term operational overheating. In many cases, we use both of them to get the benefits of each.   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 7th 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

_*]:min-w-0 !gap-3.5"> In this educational session, Adam from National Comfort Institute (NCI) delivers a comprehensive deep dive into Fan Law 2 and its practical applications for residential HVAC systems at the 6th Annual HVACR Training Symposium.  Adam begins by establishing the fundamental concepts of CFM (cubic feet per minute) and static pressure, explaining how these measurements relate to system performance. He shares a humbling personal story about learning to measure gas pressure from a homeowner, emphasizing that even experienced technicians can benefit from understanding basic measurement principles. The presentation focuses heavily on Fan Law 2, which allows technicians to predict how changes in airflow will affect static pressure in a non-proportional relationship - a critical concept for equipment sizing and replacement decisions. The core of the presentation revolves around practical applications of Fan Law 2 in real-world scenarios. Adam demonstrates how to calculate pressure drops across filters, evaporator coils, and entire duct systems when airflow changes occur. He emphasizes that static pressure increases exponentially when airflow increases, which explains why oversized systems often perform poorly. Through detailed examples using actual field measurements, he shows how a 16% increase in airflow can result in a 33% increase in static pressure, highlighting the importance of proper system sizing. Perhaps most importantly, Adam presents a systematic approach to equipment selection that goes beyond simply matching tonnage. He demonstrates how contractors can "back into" total external static pressure calculations by carefully selecting low-pressure-drop components like evaporator coils and filters. This methodology allows technicians to predict system performance before installation, preventing the common scenario where new equipment sounds "like a rocket ship" due to excessive static pressure. The presentation concludes with a compelling comparison showing how proper component selection can reduce system static pressure from over 1.0 inches to 0.64 inches while maintaining the same capacity and airflow. Topics Covered Static Pressure Fundamentals Definition and measurement using manometers Inches of water column explained Relationship between static pressure and system performance Fan Law 2 Mathematics Breaking down the intimidating formula into simple terms Step-by-step calculation examples Common mistakes when squaring numbers in calculations Practical Applications Filter pressure drop calculations at different airflows Evaporator coil pressure drop analysis Total External Static Pressure (TESP) predictions Duct system pressure calculations Equipment Selection Strategy How to select evaporator coils based on pressure drop ratings Filter sizing for optimal pressure drop Using manufacturer data sheets effectively AHRI matchup considerations beyond just capacity Real-World Problem Solving Preventing "rocket ship" installations Retrofitting existing systems with proper calculations Downsizing benefits for static pressure reduction System commissioning and performance verification Professional Development Moving beyond equipment replacement guesswork Using measurement tools like True Flow Grid Understanding manufacturer specifications Elevating installation quality through proper system design   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 7th 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 drops some knowledge to help with understanding voltage drop, a few different causes of it, and NEC recommendations. Voltage is electrical potential or "pressure," and voltage drop is the reduction in electrical potential energy. We often think of it happening across conductors (which add resistance), but it also happens across loads (like contactor coils). Voltage drop across loads is usually designed, but voltage drop across conductors is usually undesigned and undesirable.  Several factors contribute to conductor resistance. Length is a major one; long runs of wire introduce more resistance to the circuit than shorter runs. Size/gauge also matters; smaller-gauge wire has more resistance than larger-gauge wire. Copper is the most common material for wiring, but we use other materials (including steel or aluminum), and those have different resistance values. Temperature also affects resistance, as they both increase and decrease as the other one does.  When we measure voltage drop, we want to make sure we're doing it under load, NOT on startup. Voltage drops that happen on startup can be mitigated with more suitable infrastructure (including larger wires) or soft starts.  Undersized conductors don't have sufficient cross-sectional area for the applied load. To avoid voltage drop due to undersized conductors, we should size conductors based on minimum circuit ampacity (MCA), not breaker size (MOCP). Poor connections can also cause resistance to jump, which reduces voltage; we need to pay attention to the connection design (including torque specs and proper lugging) to avoid making mistakes. Long wires don't cause overheating by themselves, but they still contribute to voltage drop and cause reduced performance (including drawing higher current on startup).   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 7th 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

_*]:min-w-0 !gap-3.5"> In this enlightening presentation, Alex Meaney breaks down the fundamental concepts of airflow in HVAC systems using practical analogies and real-world examples. Rather than diving straight into complex mathematics, Alex focuses on helping technicians and contractors understand what's actually happening inside ductwork and why traditional design methods may be falling short in modern residential systems. Alex begins by addressing one of the most critical yet misunderstood aspects of ductwork: the exponential relationship between duct size and airflow capacity. He explains that the difference between a 6-inch and 7-inch duct isn't just 17% more capacity—it's actually 36% more, because airflow is determined by cross-sectional area (which increases geometrically) rather than linear measurements. This fundamental misunderstanding leads to significant underperformance in many HVAC installations. The presentation tackles the confusion surrounding pressure terminology in the HVAC industry, where the single word "pressure" is used to describe four distinct concepts: static pressure, velocity pressure, pressure loss, and external static pressure. Alex uses creative analogies, including a memorable demonstration with an inflatable tube dancer (referencing the "used car lot" in his title), to illustrate how static pressure and velocity pressure are always in balance—when one increases, the other decreases proportionally. A major focus of the discussion centers on why the traditional 0.1 inches of water column per 100 feet friction rate, long considered standard in residential duct design, is no longer adequate for modern systems. Alex explains that today's homes have evolved significantly: they're larger, use more restrictive filters for air quality, have more complex coil designs, and often place equipment in suboptimal locations. These factors combine to create much higher system resistance than the 0.1 standard was designed to handle. He advocates for using lower friction rates (like 0.06) and emphasizes that proper duct sizing is more critical than ever. The presentation concludes with practical insights about system design philosophy, emphasizing that while homeowners may not complain about poorly performing systems, HVAC professionals should use objective measurement tools rather than customer satisfaction as the primary indicator of system performance. Alex stresses that craftsmen in the field will make systems work regardless of design flaws, but this shouldn't excuse poor initial design practices. Key Topics Covered Duct Sizing Fundamentals The geometric relationship between duct diameter and airflow capacity Why linear measurements can be misleading when calculating system performance The critical importance of proper duct sizing in modern installations Pressure Concepts Demystified Static pressure vs. velocity pressure and their inverse relationship How pressure and friction work together in ductwork systems External static pressure as a measure of fan capability The role of pressure in airflow generation and control Friction and Resistance in Ductwork Understanding friction as the primary enemy of airflow How fittings create equivalent lengths of straight duct The impact of direction changes and system components on airflow Comparing flex duct vs. metal duct friction characteristics Modern System Design Challenges Why traditional 0.1 friction rates no longer work effectively The evolution of residential systems: larger homes, better filters, complex coils Equipment placement strategies and their impact on system performance The "war on sensible" and "war on blowers" affecting modern HVAC design Measurement and Verification Methods Tools for measuring static pressure and velocity pressure The importance of using objective measurement tools over customer satisfaction Available static pressure calculations and their practical applications Manual D design principles and their real-world limitations Practical Design Philosophy Working backwards from blower capacity rather than arbitrary friction rates Balancing system performance with budget constraints The importance of central equipment placement for optimal airflow Professional standards vs. "good enough" mentality in system design   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 7th 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  

_*]:min-w-0 !gap-3.5"> In this episode of the HVAC School podcast, Bryan Orr sits down with Adam and Matt to tackle one of the most misunderstood aspects of HVAC system design: return air systems. The conversation dives deep into the common myths surrounding returns, particularly the widespread belief that adding returns to rooms will automatically improve comfort and air mixing. The hosts explore why returns are often seen as mysterious - sometimes helping when added to a room, sometimes making things worse - and work to clarify the actual science behind how returns function versus how many technicians think they work. The discussion reveals a fundamental misunderstanding in the industry about the difference between supply and return air behavior. While supply air creates significant mixing effects through entrainment and the Coanda effect, returns have a much more limited impact on room air patterns. According to Manual T, laboratory tests show that return air intake influence is limited to just a few feet around the grille, even at high velocities. This leads to the key insight that returns serve primarily as pressure relief mechanisms rather than air mixing devices, which explains why their placement and sizing strategies differ significantly from supply air design principles. The hosts examine real-world scenarios, including Matt's experience with a two-story home where the homeowner requested an additional return on the second floor despite having adequate return pathways. They discuss the Manual D recommendation for returns on each floor while sharing field experiences where single central returns have successfully maintained temperature differentials within two degrees across multiple floors. The conversation emphasizes that proper system design, including accurate load calculations and right-sized equipment, often eliminates the need for complex return strategies. A significant portion of the discussion focuses on the practical considerations of passive versus active returns. The hosts lean toward passive return strategies (transfer grilles, jumper ducts, and door undercuts) for their simplicity, cost-effectiveness, and reduced ductwork requirements. However, they acknowledge the challenges of proper sizing - passive returns must be significantly larger than their active counterparts since they rely on minimal pressure differentials rather than mechanical assistance. The conversation also addresses privacy concerns with transfer grilles and the benefits of oversized jumper ducts for noise attenuation. Key Topics Covered Common Return Myths Debunked The belief that adding returns automatically improves room comfort Misconceptions about returns mixing air effectively The difference between supply air entrainment and return air influence Pressure Relief vs. Air Mixing Returns function primarily for pressure balancing, not air circulation How to measure pressure problems using flow hoods and micromanometers The impact of door closure on supply air delivery Manual D Guidelines and Field Reality Manual D recommendations for returns on each floor Real-world examples of successful single central return systems When to follow guidelines versus when field conditions allow flexibility Passive Return Strategies Transfer grilles, jumper ducts, and door undercuts as alternatives to active returns Proper sizing considerations for low-resistance return pathways Privacy and noise concerns with different passive return methods System Design Fundamentals The importance of accurate load calculations in reducing return requirements How right-sizing equipment reduces airflow and pressure management challenges The relationship between static pressure and airflow changes Zoning Considerations Whether to add dampers to returns in zoned systems Potential depressurization issues when zones are closed Passive solutions for zoned system return air management Practical Installation Tips Avoiding short-cycling by maintaining proper supply-to-return distances The risks of undersized return pathways Balancing damper selection and sealing strategies Advanced Concepts Destratification strategies using ceiling fans versus high returns The impact of conditioned versus unconditioned return air pathways Energy efficiency considerations in return system design   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 7th 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

If you're a fan of fans, this is the podcast for you! In this short podcast episode, Bryan shares how installing ceiling fans can be a smart HVAC design strategy (even though he wasn't a fan of fans!). Ceiling fans break the "don't blow air on people" rule we usually refer to in duct design, but they can solve quite a few basic comfort problems, especially in homes with lower loads than we've historically seen. They're great for creating high-velocity airstreams and mixing air. Low-load homes have systems with lower tonnages; they don't move as much air and could use a little bit of help from a ceiling fan. Air mixing is also poor in homes that have a greater distance between the air and the ceiling. Stratification of the air causes comfort problems due to temperature differences, and hot or cold surfaces can also contribute to these issues for similar reasons. Moisture and eventual growth are also concerns when we allow rooms to have those temperature differences (especially on the ceiling, as water vapor is lighter than air). Ceiling fans disrupt the stratification of air and water vapor. They solve air mixing problems while they dispel odors and maintain more consistent dew points throughout the air. Modern fans with ECMs can also run at a low speed without taking a large energy efficiency hit. Ceiling fans are great and relatively inexpensive solutions that can solve comfort and IAQ problems in high-performance homes.   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 7th 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 Orr sits down with Roman Baugh, a leading VRF (Variable Refrigerant Flow) specialist and co-host of the VRF Tech Talk podcast, for an in-depth exploration of VRF system maintenance. The conversation begins with some lighthearted back-and-forth before shifting to the technical realities of maintaining VRF equipment. Roman immediately addresses a common misconception: the idea that VRF systems are “maintenance free.” He explains that, contrary to some marketing claims, these systems require regular, specialized attention to ensure longevity and reliable performance. Roman shares real-world stories that highlight the consequences of poor installation and lack of serviceability. He describes situations where VRF units are installed in hard-to-reach locations—like cabinets or hard-lid ceilings—making even basic maintenance a costly and invasive process. This lack of foresight often leads to significant expenses for property owners, especially when major repairs require extensive drywall work just to access failed components. Roman emphasizes that proper maintenance starts with ensuring that systems are accessible and serviceable, a step too often neglected during installation. The discussion delves into the specifics of VRF maintenance, moving beyond the basics of filters and drain lines. Roman explains how improper drain line installation can lead to persistent error codes and system shutdowns, particularly when condensate pumps are forced to exceed their design limitations. He goes on to detail the critical role of temperature sensors (thermistors), which are prone to failure from corrosion, moisture, and environmental factors—especially in challenging locations like laundry rooms. These sensor failures can cause misleading error codes and even compressor damage if not addressed promptly. Roman recommends regular sensor checks, especially as components age past their typical five-year lifespan. A significant portion of the episode is dedicated to electronic expansion valves (EEVs), which are susceptible to rust, dried grease, and mechanical binding. Roman advocates for proactive inspection and, when necessary, preemptive replacement of EEVs to prevent catastrophic compressor failures. He introduces tools developed by technicians for technicians, such as the EEV Mate and custom EEV magnets, which allow for manual manipulation and diagnostics of expansion valves in the field. These innovations help HVAC professionals quickly triage and resolve issues, minimizing downtime and protecting expensive system components. The episode wraps up with a strong endorsement for ongoing education, technician communities, and the use of specialized tools and software to ensure VRF systems are maintained to the highest standard. Topics Covered: Debunking the “maintenance-free” VRF myth Access and serviceability challenges in VRF installations Proper drain line design, installation, and common failure points The role and failure modes of temperature sensors (thermistors) Environmental impacts on sensor and component reliability Electronic expansion valve (EEV) maintenance and troubleshooting Field-developed tools for EEV diagnostics (EEV Mate, EEV magnets) The importance of commissioning and using service software Application and installation quality as a foundation for long-term reliability Technician communities, podcasts, and resources for VRF learning and support This episode is essential listening for HVAC professionals seeking to deepen their understanding of VRF systems, avoid common pitfalls, and stay ahead with practical, field-tested maintenance strategies. For more insights, check out Roman Baugh’s VRF Tech Talk podcast and YouTube channel for additional resources on VRF technology and troubleshooting.   Check out the VRF Tech Talk podcast on YouTube HERE, or search for it on your favorite podcast app. 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 7th 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 explores the maintenance mindset. Maintenance procedures require a different skill set from troubleshooting, especially the customer service mindset and dedication to execution. Good maintenance is important, and it may be "boring" to some techs, but it provides value and is worth doing well. Clients purchase maintenance plans for better reliability and efficiency. Several also enjoy the health benefits of cleaner HVAC systems. The key to maintenance is having a "do no harm" mindset and a commitment to delivering value. A sales-oriented mindset should take a back seat to giving the equipment a thorough cleaning and making sure it's in proper working order; we don't want to upsell bolt-on IAQ products. Maintenance procedures are really about preventing problems and cleaning.  To give the equipment a thorough cleaning, you must pull the top off the condenser and wash it well. You may have to pull a blower wheel (which may be a quotable procedure). Good maintenance techs take pride in these types of cleaning procedures and ensure that they leave the equipment in better condition than they found it. Problem prevention is another aspect of the maintenance mindset. When you're thorough, you find things that can be fixed or adjusted to benefit the system, whether it's a wire rubout, a failing crankcase heater, a poorly fitted filter with significant bypass, or something else. Spotting and addressing these issues early requires technical expertise (just like troubleshooting) and is of excellent value to the customer.    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 7th 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 welcomes back Brynn Cooksey from Air Doctors and HVAC U to discuss critical topics facing the HVAC industry today. Brynn brings his unique perspective as both a successful contractor in southeast Michigan and an industry educator who has made the transition to focusing primarily on workforce development and training. The conversation begins with a deep dive into indoor air quality (IAQ), where Brynn challenges the common industry approach of throwing products at problems without proper testing. He emphasizes that effective IAQ solutions start with comprehensive testing to identify specific issues like high particles, volatile organic compounds (VOCs), or excessive carbon dioxide levels. Rather than relying on "magic bullet" products, Brynn advocates for a holistic approach that prioritizes ventilation strategies, source control, and proper filtration. He particularly stresses the importance of the "V" in HVAC, ventilation, which he believes is often overlooked in favor of flashier solutions. His company's protocol of testing on every customer visit, from first encounters to maintenance calls, has created a culture where technicians become comfortable discussing IAQ solutions based on actual data rather than assumptions. The discussion transitions into ethical sales practices, a topic that resonates strongly in an industry where pressure to sell can sometimes conflict with customer needs. Brynn defines unethical sales as pressuring customers into products that won't benefit them or failing to provide complete information about benefits and consequences. His approach centers on thorough customer surveys to understand actual problems and budget constraints, followed by tying specific solutions to identified issues. This methodology puts the customer in control of decisions while positioning the contractor as a trusted advisor rather than a high-pressure salesperson. Brynn argues that price alone doesn't determine ethics - rather, it's the intent behind recommendations and the transparency of communication that matters most. The final segment focuses on workforce development, an area where Brynn has found significant success. His company's registered apprenticeship program, developed through the Department of Labor, has become a competitive advantage in attracting talent while providing structured, in-house training. The program requires minimal cost beyond commitment to ethical treatment of apprentices and systematic tracking of their progress. Brynn's transition from contractor to educator demonstrates the growing need for comprehensive training programs that go beyond basic technical skills to include building science, customer service, and ethical business practices. His ongoing weekly training sessions focus on field trends and callback prevention, contributing to an impressive callback rate of less than 0.5%. Topics Covered Indoor Air Quality Testing and Assessment Using monitors like Air Advice for comprehensive IAQ evaluation Implementing testing protocols on every customer interaction Moving beyond product-focused solutions to holistic approaches Ventilation Strategies and Building Science The importance of mechanical ventilation and ERV systems Understanding the relationship between building envelope leakage and humidity issues Source control as the foundation of effective IAQ management Ethical Sales Practices Defining unethical sales and pressure tactics Customer survey techniques and solution-tying methodologies The concept of fiduciary duty in HVAC contracting Equipment Sizing and System Design The impact of oversized equipment on IAQ and comfort Proper load calculations and duct system design Static pressure testing and airflow optimization Workforce Development and Training Implementing registered apprenticeship programs Weekly training sessions focused on field trends and callback prevention Transitioning from contractor to educator and industry trainer Building Envelope and Duct System Integrity Air sealing strategies for improved humidity control The relationship between leaky envelopes and indoor air quality Duct modifications and system upgrades Customer Education and Professional Positioning Using testing data to support recommendations Overcoming price objections through professional credibility Building long-term customer relationships through transparency   Learn more about Brynn's work at hvactrain.com. You can also read his article in Forbes at https://www.forbes.com/sites/brynncooksey/2025/02/19/rescuing-children-from-traditional-post-k-12-school-paths/. Learn more about the GRIT Foundation at https://www.thegritfoundation.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 7th 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 crankcase heaters, including their different types, what they do, and when we need to use them. Crankcase heaters usually come in belly band varieties, but some can be inserted into the sump of the compressor. As their name suggests, crankcase heaters heat the crankcase when the compressor is off. They prevent flooded starts since the heat keeps refrigerant from condensing to a liquid in the compressor when the system isn't running. Long off times, long line sets, and cold temperatures all increase a system's risk of flooded starts. Hard shutoff TXVs, liquid line solenoid valves, and crankcase heaters are all ways to reduce these risks; the valves hold liquid refrigerant back, and crankcase heaters merely prevent refrigerant from condensing. Crankcase heaters have to be wired to the line side of the contactor or starter. They're often wired around one of the contacts (with a single-pole contactor). When the contact opens, there is a circuit from one leg, through the crankcase heater and compressor windings, to the other leg. This method does NOT use the compressor winding itself as a crankcase heater. When you use a crankcase heater on a compressor with a seam, you want the part of the heater that does the tensioning near the seam. Crankcase heaters should be installed at the base of the compressor, and you'll usually use OEM crankcase heaters.   "Crankcase Heaters and Single-Pole Contactors" tech tip: https://www.hvacrschool.com/crankcase-heaters-and-single-pole-contactors/  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 7th 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