In this live episode from the AHR 2026 Podcast Pavilion, Bryan sits down with Copeland's Josh Souders (Manager of Commercial Unitary Product Management) and Jeff Kukert (Compression Senior Technical Trainer) to dive deep into Enhanced Vapor Injection (EVI) technology and its transformative impact on HVAC systems. This conversation offers both technical professionals and industry newcomers a comprehensive look at how vapor injection is revolutionizing heat pump performance, particularly in challenging climate conditions.

The discussion centers on how EVI technology addresses one of the industry's most persistent challenges: maintaining high heat pump capacity in extremely low-temperature conditions. Josh and Jeff explain that vapor injection can deliver up to 20% added capacity and 10% improved efficiency while simultaneously enhancing compressor reliability. This technology, which has been a staple in refrigeration applications for years, is now becoming increasingly prevalent in commercial and residential HVAC systems, especially as cold climate heat pumps gain traction across North America. The guests make the complex topic accessible by breaking down how the system works—taking liquid refrigerant from the condensing line, running it through an expansion device and brazed plate heat exchanger (economizer), and injecting the cooled vapor directly back into the compressor scroll at a specific intermediate point.

What makes this episode particularly valuable is the practical guidance offered for field technicians. The conversation moves beyond theoretical explanations to address real-world implementation challenges and troubleshooting strategies. Josh and Jeff emphasize the importance of understanding operating envelopes, pulse-width modulated (PWM) valves, pressure transducers, and modern control systems. They introduce Copeland's latest product developments, including the YAW variable speed vapor injection platform (1.5 to 25 tons) and the upcoming YAB two-stage vapor injection system launching later in 2026. The discussion also touches on applications beyond traditional HVAC, including commercial water heating and boiler replacement systems where high discharge temperatures are crucial.

Throughout the episode, the guests maintain an encouraging tone toward technicians who may feel intimidated by these advancing technologies. They stress that while EVI systems may appear complex with additional tubing, heat exchangers, valves, and sensors, the underlying thermodynamic principles remain the same. The key is familiarizing oneself with new components like PWM valves and modern controllers, and leveraging tools like Copeland Mobile to verify system performance against operating envelopes. This episode serves as both an educational resource and a call to action for HVAC professionals to embrace these emerging technologies that are rapidly becoming industry standard.

Topics Covered

• Enhanced Vapor Injection (EVI) fundamentals – How EVI works, its history in refrigeration, and why it's now critical for commercial and residential HVAC applications
• Capacity and efficiency benefits – Achieving up to 20% capacity boost and 10% efficiency improvement, particularly in low-ambient heating conditions
• Compressor reliability improvements – How injecting cooled vapor into the scroll set manages discharge temperatures and extends compressor life under high compression ratios
• Operating envelope management – Understanding compressor operational limits and using tools like Copeland Mobile to verify field conditions stay within safe parameters
• Cold climate heat pump technology – Meeting DOE's Cold Climate Heat Pump Challenge requirements for 100% capacity at 5°F ambient conditions
• System architecture and components – Detailed explanation of economizers (brazed plate heat exchangers), pulse-width modulated (PWM) valves, pressure transducers, and advanced controllers
• Compression ratio challenges – Managing the increased work required when outdoor temperatures drop while indoor condensing temperatures remain constant
• New Copeland product platforms – Introduction to YAW variable speed vapor injection (1.5-25 tons), YAB two-stage vapor injection (launching 2026), and tandem variable speed configurations
• Applications beyond traditional HVAC – Water heating systems, commercial boiler replacement, and managing high discharge temperatures for Legionella protection
• Technician training and tools – Practical advice on learning PWM valves, thermistors, transducers, and system controllers; emphasis on using Copeland Mobile for dynamic performance analysis
• Market trends and adoption – How vapor injection is becoming standard in premium residential systems and increasingly common across commercial rooftop units and dedicated outdoor air systems
• Installation and service considerations – Proper system design to avoid oversizing, humidity control in hot-humid climates, and troubleshooting techniques for complex control systems

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

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In this short podcast episode, Bryan breaks down the differences between a thermostatic expansion valve (TXV) and an electronic expansion valve (EEV). He highlights their strengths and weaknesses.

In the basic refrigerant circuit, the metering device drops the pressure. TXVs and EEVs are both metering devices that cause the liquid refrigerant to drop in pressure and become a liquid-vapor mixture; they control evaporator feeding and maintain a constant superheat.

TXVs achieve this by mechanical means; the bulb responds to suction line temperature and evaporator pressure at the valve. They are self-contained and easy to diagnose with basic refrigeration measurements. However, they are prone to mechanical failures, including clogged orifices and screens, cracked capillary tubes, and powerhead leaks. Installation errors are also easy to make, and TXVs can hunt in low-load conditions. Overall, failures are often mechanical and refrigerant-related. They win in the simplicity department.

EEVs receive inputs from sensors and modulate in response to those digital signals. They have a wider modulation range and maintain stable control in low-superheat applications, and they do well in conditions with highly variable loads or where coordination across multiple coils is required. EEVs come in two types: stepper motor (small, discrete steps) and PWM (controlled solenoid valves). Stepper-style EEVs excel at fine positioning, and PWM-style EEVs are in applications that require a more robust valve (like CO2 refrigeration). EEV failures are often electromechanical or related to sensor control. They win in the controllability department.

There is no "best" metering device; they merely have different strengths that make them better suited to different applications. However, EEVs are the future due to the greater degree of controllability we will need in newer equipment. Commissioning and airflow are also crucial for getting the most out of both metering device types in terms of longevity and reliability.

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

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In this informative episode, host Bryan welcomes guest Bert for an in-depth discussion on the often-overlooked but critically important topic of electric heat in HVAC systems. The conversation takes listeners through both the common and uncommon issues that arise with electric heat installations, offering practical insights drawn from years of field experience. Bryan and Bert balance technical expertise with relatable storytelling, making complex electrical concepts accessible to both HVAC professionals and homeowners interested in understanding their heating systems.

The discussion begins with some of the more dramatic (and rare) scenarios, including tales of objects left on heat strips during installation—from instruction manuals to spray glue cans—that have led to fires and property damage. These cautionary tales serve as memorable reminders of the importance of proper installation practices. The conversation then shifts to the far more common issues technicians encounter regularly, particularly loose electrical connections. With electric heat strips drawing substantial continuous amperage—often 20 amps per 5kW or more—poor connections can quickly lead to melted wire nuts, damaged terminal blocks, and potentially dangerous situations. Bryan and Bert emphasize that these connection problems often don't manifest until the heating season begins, making proper installation and inspection critical.

Bryan and Bert also address widespread confusion around emergency heat versus auxiliary heat, explaining why emergency heat settings are largely obsolete in most modern heat pump applications. They clarify that in typical residential installations with 5-10kW heat strips, the electric backup cannot efficiently heat an entire home on its own, making the emergency heat function impractical. Instead, auxiliary heat should work in tandem with the heat pump to supplement heating during extremely cold conditions or defrost cycles. The hosts advocate for implementing lockout controls that prevent auxiliary heat from activating unless outdoor temperatures drop below 40 degrees, helping homeowners avoid unnecessarily high electricity bills while still maintaining comfort.

The technical discussion extends to critical safety mechanisms, including interlocks, thermal overloads, and fusible links that prevent catastrophic failures. Bryan provides historical context on how interlock systems have evolved from high-voltage relay-based designs to modern control board logic, while warning against improper retrofitting that can create new hazards. The episode concludes with practical guidance on proper sizing, voltage considerations, airflow requirements, and the economics of electric heat versus other fuel sources. Throughout the conversation, Bryan and his guest stress that while electric heat is simple and reliable, it demands respect for proper electrical practices and thoughtful system design to ensure both safety and cost-effectiveness.

Topics Covered

• Installation Horror Stories and Safety Hazards: Objects left on heat strips causing fires, including the infamous spray glue can incident
• Loose Electrical Connections: The #1 issue with electric heat systems and why continuous high amperage makes proper connections critical
• Wire Sizing and Breaker Matching: Common mistakes when replacing furnaces with heat pumps and the dangers of undersized wiring
• Emergency Heat vs. Auxiliary Heat: Why emergency heat is largely obsolete in modern residential applications and when auxiliary heat should actually engage
• Heat Output Calculations: Understanding BTU production per kilowatt (3.41 BTUs per watt) and why 5-10kW strips can't heat most homes alone
• Lockout Controls and Outdoor Thermostats: Implementing temperature-based restrictions to prevent unnecessary auxiliary heat operation above 40°F
• Interlock Systems Evolution: How blower/heat strip safety interlocks have changed from relay-based to control board logic
• Thermal Overloads and Fusible Links: The two types of safety devices that prevent overheating and fire hazards
• Defrost Cycle Operation: How auxiliary heat integrates with heat pump defrost sequences
• Balance Point and Dual Fuel Considerations: Economic and operational factors in choosing between electric and gas backup heat
• Voltage Variations and Sizing: Working with different voltage ratings (208V vs. 240V) and how they affect heat output
• Diagnostic Techniques: Using Ohm's law and resistance measurements to verify heat strip operation and specifications
• Airflow Requirements: Why proper air movement is critical for preventing overload trips and premature failures
• Electrical Safety Practices: Avoiding dangerous shortcuts like bypassing thermal limits or using undersized relays
• Energy Efficiency and Economics: Comparing the true cost-effectiveness of electric heat versus gas and heat pump operation

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

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In this short podcast episode, Bryan talks about some building science concepts, including vapor diffusion ports, hygric buoyancy, and... fruit packaging?

Much of building science wisdom over the past couple of decades has dealt with air sealing (just seal it tighter!). However, building tightness has a darker side: more difficulty drying. When buildings can't dry, moisture accumulates and leads to rot.

Air leaks and vapor diffusion are NOT the same thing. Vapor diffusion refers to water vapor diffusing through surfaces into the home (through the materials of walls, floors, etc.). Air moves much more water than vapor diffusion, so air leaks are a bigger problem in terms of moisture. Therefore, air barriers matter more than vapor barriers... until the air barrier battle has been won.

Hygric buoyancy refers to moist air's lower density than dry air, so wet air rises toward the attic (and then the attic peaks). While sealed attics are excellent, moisture can accumulate at the roof deck, especially when the roofing cools at night. The condensation is worsened by using open-cell foam, as open-cell foam is air-closed but vapor-open (whereas closed-cell foam is air-closed AND vapor-closed). Drying isn't needed if you can KEEP the moisture out of closed-cell foam. Open-cell foam requires a place for vapor to go.

Vapor diffusion ports are airtight, controlled vapor-open outlets at the highest points of sealed attics. A cap protects them from bulk water, and they consist of a membrane that blocks air but allows vapor to exit. Unlike a ridge vent, ventilation is not the goal of a vapor diffusion port; it is drying by diffusion rather than airflow and acts as a controlled pressure-relief valve for moisture. Vapor diffusion ports have been proven to be effective at drying and preventing roof rot in humid climates (but NOT ALL climates). They do not work against bulk water intrusion, in cold climates, or when used as vents. Vapor diffusion ports work like fruit packaging, which is designed to let oxygen in and CO2 out, while controlling moisture and slowing decay.

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

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In this informative episode, Bryan and Bert dive deep into gas appliance safety and combustion analysis from the unique perspective of Florida HVAC technicians. While they humorously acknowledge that Florida's mild winters mean they don't work on gas furnaces daily, they make a compelling case that this actually makes their training even more critical. When technicians only encounter gas appliances occasionally, the stakes are higher—which is why they've developed rigorous protocols to ensure safety every single time.

The conversation covers everything from the basics of gas leak detection to the nuances of carbon monoxide monitoring, combustion air zones, and proper venting. Bryan and Bert share real-world stories of dangerous situations they've encountered, from exploding pool heaters to improperly capped gas lines at vacation rentals. Their approach emphasizes that every gas leak is your problem when you're on site, regardless of why you were originally called out. This episode is packed with practical wisdom for both seasoned professionals working in gas-heavy markets and those who encounter these systems less frequently.

Throughout the discussion, the hosts stress fundamental safety principles that apply across all markets: using your nose to detect leaks, understanding the difference between unspent gas and carbon monoxide, ensuring proper combustion air zones, and never ignoring warning signs like delayed ignition or flame rollout. They also tackle common misconceptions about equipment like flexible gas connectors, orphaned water heaters, and the real risks of cracked heat exchangers.

The conversation wraps up with important reminders about company lockout/tagout procedures, the critical importance of low-level carbon monoxide detectors, and the tools every technician should carry. Bryan and Bert's candid, no-nonsense approach makes complex safety topics accessible while never losing sight of how serious the consequences can be when gas work goes wrong.

Topics Covered

• Gas leak detection and response protocols - Why every gas leak on site becomes your responsibility, using your nose as the first line of defense, and never leaving a leak for someone else to fix
• Carbon monoxide safety and monitoring - Understanding CO as a combustion byproduct, the limitations of standard UL-rated detectors, and the critical importance of low-level CO monitors
• Combustion air zones and depressurization - Identifying risks from sealed spaces, return air leaks, exhaust fans, and other equipment that can create dangerous negative pressure
• Delayed ignition and flame rollout - Recognizing warning signs, understanding causes, and why you should never ignore scorched wires or tripped rollout switches
• Proper gas line assembly and materials - Selecting appropriate materials for different environments, avoiding flexible connector failures, and ensuring proper sizing
• Combustion analysis fundamentals - Measuring CO levels in the flue, targeting air-free CO under 100 ppm, and understanding when adjustments are needed
• Natural draft vs. induced draft systems - Differences in safety considerations, orphaned water heaters, and the myth of oversized flue pipes
• Venting requirements and back drafting - Identifying improper venting, looking for evidence of back draft on water heaters, and ensuring proper flue design
• Gas pressure testing and adjustment - When to adjust and when not to, reading data tags, and understanding that most flame problems are air-related, not gas pressure
• Cracked heat exchangers in context - Why they're less common in warm climates, the role of proper airflow, and focusing on actual safety risks vs. edge cases
• Tools and equipment recommendations - Combustion analyzers, personal protective CO detectors, combustible gas detectors, precision manometers, and low-level CO alarms
• Lockout/tagout procedures - Following company protocols, communicating clearly with customers, and balancing safety requirements with homeowner autonomy

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

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In this short podcast episode, Bryan dives a bit into equipment sizing rules of thumb and why square footage does NOT equal tonnage in today's world. Many rules of thumb exist in the industry, and one is a load calculation rule stating that you can size the HVAC for a house at 500 square feet per ton.

Old houses are leaky and poorly insulated compared to new homes, which results in large energy loads but allows the homes to dry themselves out, as moisture could leak out before it could cause trouble indoors. Large loads and leaky envelopes made 500-600 square feet per ton a sensible rule.

Homes built within the last few decades have a lot more insulation and are tighter, and they have smaller sensible heat loads. However, they're a lot more moisture-prone, especially when moisture can't escape via proper ventilation paths. The 500 square-foot rule of thumb overshoots the latent capacity and leads to short cycling due to oversized equipment. Enter ACCA Manual J, which presents a load calculation method that is very good, but it has barriers to entry; it is very rigorous, has a learning curve, and can be a hassle. One thing is clear, though: load management is key, especially latent load management.

At this time, we measure energy efficiency in terms of metrics like SEER, but the future is pointing to peak load management as the answer: getting the right power draw at the right moments instead of high general efficiency. Modernizing hot deck-cold deck systems with steady-state, constantly running systems might be the way to go, especially if we utilize energy storage and modern variable-speed technologies.

The new rule of thumb is to think like a building scientist and apply new tools to concepts that have stood the test of time. Low peak loads and steady-state operation are often the way to go with high latent loads in homes built to the most recent building codes and standards.

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

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Matthew Taylor delivers an expert-level presentation on EPRs, building on his previous work on parallel rack systems. While his earlier content focused on the similarities between air conditioning and refrigeration, this session explores what makes commercial refrigeration unique—particularly the critical role of EPRs in maintaining optimal operating conditions across multiple evaporators running at different temperatures. This presentation was shared at the 6th Annual HVACR Training Symposium.

The discussion begins with a fundamental review of the refrigeration cycle in a typical supermarket setting, where 30 to 80 evaporators may share a common suction line. Matthew explains why EPRs are essential: when multiple cases need to operate at different temperatures (ranging from -13°F for frozen foods to 24°F for fresh products) but all connect to the same compressor rack, EPRs become the solution that makes this possible. Without them, cases would cycle on and off constantly, creating efficiency nightmares, oil management problems, and potential food safety issues.

Matthew walks through the mechanical principles of various EPR types, from the high-efficiency Sporlan SORIT valve with its pilot-operated design to the Parker A8 valve that can be installed directly in the store. He also addresses the industry's shift toward electronic EPRs, particularly the CDS modules that offer temperature-based control rather than just pressure regulation. Throughout the presentation, Matthew emphasizes practical considerations: how EPRs affect compressor staging, oil system pressure, defrost cycles, and ultimately, the core product temperatures that determine food safety. The session includes real-world troubleshooting insights and addresses common misconceptions about setting superheat on systems with EPRs.

This technical presentation provides HVAC professionals with the knowledge needed to understand, diagnose, and service EPR-equipped refrigeration systems confidently. Matthew's approach demystifies a component that many technicians find intimidating, breaking it down into understandable principles while highlighting the critical role EPRs play in modern commercial refrigeration efficiency and reliability.

Topics Covered

• Basic Refrigeration Cycle in Supermarket Applications – Understanding parallel rack systems with 30-80 evaporators sharing common suction and liquid lines
• Oil Management Systems – Oil separators, oil reservoirs, oil regulators, and the critical pressure differential required for proper oil flow
• Compressor Staging and Capacity Control – How parallel rack compressors operate as multi-stage units to match system load efficiently
• Saturated Suction Temperature (SST) – Why racks are designated by temperature (e.g., "13-degree rack" or "-13 degree rack") and how this relates to the coldest evaporator requirement
• Temperature Difference (TD) Engineering – The relationship between evaporator temperature and case leaving air temperature, typically 10 degrees in traditional systems
• EPR Fundamentals – Why EPRs are necessary to maintain different evaporator pressures on cases operating at various temperatures while connected to a single rack
• Mechanical EPR Types – Comparison of Sporlan SORIT valves (pilot-operated, low pressure drop) versus Parker A8 valves (self-contained, higher pressure drop)
• Electronic EPR Systems – Modern CDS modules and other electronic controls offering pressure control, temperature control, or hybrid approaches
• System Stability and Load Management – How proper EPR settings prevent compressor hunting, reduce energy consumption, and protect oil management systems
• Subcooling Requirements – Why liquid receivers eliminate natural subcooling and how mechanical subcoolers restore it before expansion devices
• Core Product Temperature – The critical relationship between runtime, EPR settings, and food safety in refrigerated cases
• Dual-Temperature Applications – Converting medium-temp cases to low-temp operation (like holiday turkey displays) using EPR pilot solenoids
• Superheat Setting Procedures – Why EPRs must be overridden to 50-100% open position when setting TXV superheat
• High Glide Refrigerants – Special considerations for setting EPRs with refrigerants that have significant difference between dew point and bubble point temperatures
• Troubleshooting Philosophy – Understanding EPRs and TXVs as independent systems that don't directly affect each other due to non-critically charged liquid receiver systems
• Pressure Drop Considerations – How EPR pressure losses (0.5-2 psi depending on type) affect compressor suction setpoints and energy efficiency
• Electronic Control Integration – Various controller brands and approaches to managing electronic EPRs, from pressure transducers to temperature sensors and PID algorithms

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

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In this short podcast episode, Bryan covers the history of the great heating debate: furnaces vs. heat pumps or combustion vs. compression. He also gives a breakdown of each other's strengths and gives his two cents on the winner of the debate.

Fire kept humans warm for much of history, but engineers developed a way to move heat by manipulating refrigerant pressures. Early heat pumps got a bad rap because they didn't live up to the hype; they had frequent operational issues, didn't heat effectively, and were largely unable to be serviced effectively by technicians.

However, heat pumps have evolved and now outperform furnaces in many areas. Ones with COPs between 2 and 5 can be anywhere from 200-500% efficient in terms of watts in, BTUs out. They also have many safety benefits over gas furnaces, including no risk of flame rollout, carbon monoxide poisoning, and gas leaks; removing the gas meter and all its risks entirely is a possibility.

Nevertheless, some people still insist that combustion is king due to its comfort, as furnaces' heat is more intense than that of heat pumps. Furnaces also require little electricity, making them more sensible in markets with weak or dirty electrical grids. Combustion appliances also only need to work part of the year, meaning they run fewer cycles and experience less mechanical wear over the same period of time as heat pumps (thus may have longer lifespans).

Dual fuel allows you to get the best of both worlds; it allows the heat pump to handle the cooling and most of the heating for the energy efficiency benefits, and the furnace can step in when more intense heat is needed. Ultimately, the "winner" of this debate, at least to Bryan, is the most sensible solution for energy costs, safety, comfort, and reliability; the real answer will depend on the climate, infrastructure, and other factors.

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

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In this engaging episode of the HVAC School podcast, host Bryan Orr sits down with Leo and Paul Sharkey, a father-son duo of mechanical engineers who made the leap into the HVAC business. Leo and Paul share their remarkable journey of purchasing an HVAC company in September 2020 and quadrupling its revenue within five years. Their engineering backgrounds bring a refreshing, data-driven perspective to an industry that often relies on rules of thumb and outdated practices.

The Sharkeys operate in the challenging Northeast market, where homes can date back to the 1600s and 1700s. They discuss the eye-opening discovery that traditional HVAC sizing methods—like the simplistic "one ton per 400 square feet" rule—fail dramatically in older housing stock. Their commitment to running thousands of Manual J calculations has transformed their approach, often resulting in smaller, more efficient systems than competitors propose. The conversation dives deep into the unique challenges of working with centuries-old New England homes, including extreme infiltration rates, non-linear heat loss curves during harsh winters, and the complications of mixing modern additions with ancient construction.

Beyond sizing, Leo and Paul tackle the practical realities of heat pump installations in cold climates. They explain why turndown ratio is critical, how they handle homes with heat loads that triple their cooling loads, and when backup heating systems are truly necessary. Their consultative approach rejects the "one-size-fits-all" mentality that has flooded the market with incentive-chasing installations. They candidly discuss the problems created by Massachusetts' generous rebate programs, which have attracted fly-by-night operators who prioritize rebate qualifications over proper design and long-term performance.

The episode also explores the balance between ductless and ducted systems, revealing when each approach makes economic and technical sense. The Sharkeys share fascinating case studies, from a 1748 house with the equivalent of a full-size door's worth of air leakage to underground concrete dome homes requiring specialized dehumidification. Their willingness to take on complex projects that other contractors avoid demonstrates how engineering thinking, combined with trade expertise, can solve challenging HVAC problems. This conversation is essential listening for anyone serious about understanding cold climate HVAC design, building science principles, and what it takes to deliver quality comfort solutions in real-world conditions.

Topics Covered

• Engineering background transition to HVAC - How mechanical engineering experience in semiconductors and manufacturing informed their HVAC business approach
• Manual J calculations and proper sizing - Running 7,000-9,000 Manual J calculations over five years and why they typically specify smaller systems than competitors
• Old New England housing challenges - Working with homes from the 1600s-1700s, extreme infiltration rates, and heat loss characteristics of ancient construction
• Heat load vs. cooling load imbalances - Managing homes where heat loads can be triple the cooling loads and how this affects system design
• Heat pump turndown ratios - Why equipment turndown capability is critical for shoulder seasons and preventing short cycling in cold climates
• Cold weather performance and derating - Equipment capacity loss at low ambient temperatures and the importance of proper backup heat sizing
• Ductless vs. ducted system economics - When to choose multi-zone ductless over ducted systems based on home layout, infrastructure, and cost
• Retrofit complications in mixed construction - Dealing with homes that combine 200-year-old sections with modern additions on the same heating system
• Massachusetts incentive programs - How Mass Save rebates (up to $25,000 financing + $10,000 rebates) have impacted market quality and contractor behavior
• Installation challenges at low temperatures - Field issues including undersized ductwork, poor equipment placement, defrost cycle complications, and electric backup heat requirements
• Building science fundamentals - Blower door testing, weatherization impacts, infiltration effects on heat load, and wind loading considerations
• Consultative sales approach - Rejecting one-size-fits-all solutions and customizing system recommendations based on home characteristics and homeowner needs
• Backup heating strategies - When and why fuel-based backup systems are necessary, including power outage considerations and client comfort levels
• Complex project examples - Case studies including underground concrete dome homes, storage closet air handler installations, and severely under-designed retrofit corrections

Learn more about Leo and Paul's business, Jay Moody HVAC, at https://jaymoodyhvac.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.

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

In this short podcast, Bryan answers a listener-submitted question and explains why heat pumps get a bit weird: when it comes to superheat in heat mode. He also explains how we can move heat from outdoors to indoors, even in temperatures below freezing (cold temperatures just have less heat, not zero heat).

In order to move heat in very cold conditions, we need very low suction pressures and cold coils, which gives us a high compression ratio. Superheat will be affected by these conditions. Remember: superheat that is too low can cause floodback, and superheat that is too high can cause the compressor to overheat.

Superheat is easy to check in cooling mode, but it's harder in heating mode, especially since the suction line is at the outdoor unit. In heating mode, we can only measure superheat between the coil outlet and the reversing valve inlet, which is a very short run of tubing.

The superheat will also be less stable in heat mode in cold weather, and it will have a wider range of "normal" values than cooling mode, depending on the conditions. Superheat could even drop to zero with some fixed-orifice metering devices (which would cause floodback). That's why many of these heat pumps have accumulators, which collect liquid refrigerant to protect the compressor. Even though TXVs attempt to maintain superheat, you may still see some variation in heat mode during cold weather. EEVs are common in ductless systems and are highly controllable but maintain relatively low superheats by design; fast metering control, intelligent logic, accumulators, and low refrigerant charges allow them to avoid floodback in low temperatures.

In any case, spikes and drops in temperature can cause the superheat to jump or collapse because the load changes (as the outdoor coil is the evaporator). Frost buildup on the coil also inhibits airflow and heat transfer, causing the superheat to change as the evaporator pressure and temperature drop. Defrost also introduces chaos to the equation. All of these should influence your judgment when checking superheat to diagnose or commission a system in heat mode.

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.

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In this engaging and informative episode, Bryan sits down with Elliot to discuss his recent training experience with the National Comfort Institute (NCI), covering two intensive courses on duct system optimization and residential air balancing. The conversation offers valuable insights for HVAC professionals looking to improve their technical skills and provide better service to their customers. With a mix of technical expertise and practical field experience, this episode breaks down complex HVAC concepts into actionable strategies for contractors and technicians.

Elliot shares his key takeaways from the NCI training, emphasizing how the courses filled critical knowledge gaps about the "invisible stuff" in HVAC systems—the air itself. The discussion reveals a common industry problem: most HVAC professionals focus heavily on equipment while neglecting proper duct design and air balancing. Elliot explains how he learned to move beyond guesswork in duct design, discovering that flex duct has actual CFM ratings and that proper system design requires understanding static pressure, equivalent length of fittings, and the science behind airflow. The conversation highlights the importance of oversized return air systems—a point both hosts stress repeatedly—and explains why Florida (and possibly the entire nation) suffers from chronically undersized returns. The hosts discuss various duct system approaches, from traditional trunk lines to the flex-and-fitting systems, acknowledging that different markets require different solutions based on climate, building construction, and supply chain availability.

Throughout the episode, Bryan and Elliot tackle practical installation challenges that technicians face daily. They discuss the importance of proper flex duct installation, explaining how compressed or sagging ductwork dramatically reduces airflow efficiency. The conversation covers the critical role of balancing dampers in every branch run, the impact of proper duct strapping, and how simple adjustments like straightening kinked flex duct can immediately improve CFM delivery. The hosts also address the limitations of builder-grade installations, noting that most new construction lacks the dampers necessary for proper air balancing. They emphasize a practical, process-based approach to HVAC work that focuses on getting clients measurable results without requiring perfect conditions or unlimited budgets.

The episode concludes with a strong endorsement of the National Comfort Institute's training programs and tools, particularly the TrueFlow Grid and measureQuick technologies that simplify complex air balancing calculations. Bryan and Elliot stress the importance of ethical, high-performance contracting that delivers real value to customers rather than just marketing sizzle. They encourage HVAC professionals to invest in training and proper tools, acknowledging that while the initial investment may seem steep, the ability to provide superior service and reduce callbacks makes it worthwhile. The conversation serves as both a technical deep-dive and a call to action for contractors to elevate their skills and focus on the whole system—equipment, ductwork, and building envelope—to truly solve customer comfort problems.

Topics Covered

• NCI Training Experience - Elliot's overview of the duct system optimization and residential air balancing courses, including instructor quality and course relevance to Florida's HVAC market
• Duct Design Fundamentals - Moving from guesswork to calculated design using CFM ratings, square footage calculations, and proper system output considerations
• Static Pressure Management - Understanding static pressure drop across coils, the importance of variable speed fans, and strategies to reduce total external static pressure
• Return Air Systems - Why bigger returns are always better, the critical importance of oversized return grills, and the impact of filter face velocity on system performance
• Equivalent Length of Fittings - How fittings add "phantom" duct length to runs, techniques to reduce equivalent length, and the dramatic impact of turning vanes on 90-degree turns
• Flex Duct vs. Trunk Lines - Comparing different duct system approaches across various markets, the pros and cons of metal, duct board, and flex systems, and the flex-and-fitting methodology
• Proper Flex Installation - The importance of stretching flex duct correctly, proper strapping techniques, and how sagging or compressed flex drastically reduces airflow
• Air Balancing Techniques - The necessity of balancing dampers in every branch run, methods for achieving proper air distribution, and using velocity comparisons for troubleshooting
• Throw and Mixing in Rooms - Understanding that grills, not duct size, control air throw and mixing, and the role of Manual T in selecting appropriate terminal devices
• Practical Installation Tips - Simple improvements technicians can make during service calls, like straightening kinked ductwork and adding straps to reduce sag
• High-Performance Tools - The TrueFlow Grid, measureQuick app, hot wire anemometers, and other technologies that simplify complex air balancing calculations
• Building Performance Perspective - Moving beyond equipment-only focus to consider the entire system: ductwork, building envelope, and how they all interact
• Ethical Contracting - Delivering real value to customers, avoiding the "all sizzle, no steak" approach, and providing solutions that work within real-world budgets and constraints

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