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HVAC School - For Techs, By Techs

HVAC School - For Techs, By Techs

Auteur(s): Bryan Orr
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À propos de cet audio

 HVAC School is the ever growing online source for real training topics for technicians in the Air-conditioning, Heating and Ventilation Fields. In the podcast, we will share recorded training, tech ride alongs, share challenging diagnostic scenarios. All to help make the industry, your company, and your truck a better place to be. Développement personnel Gestion et leadership Réussite Économie
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  • Are Two Are Better Than One: Understanding Tandem Compressors

    Are Two Are Better Than One: Understanding Tandem Compressors
    Dec 4 2025
    In this comprehensive episode of the HVAC School podcast, host Bryan Orr sits down with three experts from Copeland to demystify tandem and trio compressor systems. Joining him are Gina Kahle (Multiples Engineering Manager with 12+ years at Copeland), Tyler Daniels (Product Management team member), and James Stevenson (Technical Sales veteran with 28 years of field experience). Together, they provide both the engineering perspective and real-world service insights that technicians need to understand these increasingly common systems. The conversation begins with the fundamentals: tandem and trio systems represent an evolution in compression modulation, allowing multiple compressors to work together on a single circuit rather than requiring separate circuits for each compressor. This design philosophy delivers significant advantages, including energy savings through better modulation, simplified system design, reduced costs, and the ability to meet stringent minimum modulation requirements (such as the 25% threshold for units under 60,000 BTUs per hour). The team emphasizes that tandems aren't just about pairing any two compressors together—Copeland engineers carefully consider application requirements, flow characteristics, and stress testing to ensure reliable oil management and system resonance control. A major focus of the discussion centers on practical service considerations that every technician needs to understand. James provides invaluable guidance on identifying whether a failed compressor in a tandem system can be replaced individually or requires replacing the entire tandem assembly. The "rule of thumb" is clear: compressors small enough to fit in residential systems (typically under 10 horsepower or about 7 inches in diameter) generally require full tandem replacement, while larger units may allow single compressor replacement. The distinction between "tandem ready" and non-tandem ready compressors becomes critical here—larger compressors (10+ horsepower) are typically sold tandem ready at wholesalers with the necessary oil equalization ports and sight glass connections, while smaller units are not. The episode also explores advanced topics, including the integration of Enhanced Vapor Injection (EVI) technology with tandem systems, particularly for cold climate heat pump applications. Gina explains how EVI extends the operating envelope down to -40°F, opening new markets and applications. The team discusses the transition to A2L refrigerants and how Copeland continues to innovate despite changing regulatory landscapes. Throughout the conversation, they emphasize the critical importance of proper oil management through oil equalization lines (OEL) and two-phase transfer lines (TPTL), and why maintaining these connections exactly as designed is non-negotiable for system longevity. Key Topics Covered: Tandem and Trio Basics: Definition and benefits, including energy savings, cost reduction, and design simplificationModulation Requirements: Meeting state-mandated minimum modulation thresholds (25% for units under 60,000 BTU/hr) Applications: Data centers, DOAS units, rooftops, chillers, and various commercial spacesCompressor Pairing Options: Fixed speed, digital, variable speed, two-stage, and mixed configurationsOil Management: Critical importance of oil equalization lines (OEL), two-phase transfer lines (TPTL), and gas equalization lines (GEL)Service and Replacement: How to identify tandem-ready vs. non-tandem-ready compressors; when to replace individual compressors vs. full tandem assembliesVisual Identification: Using compressor size (7" vs 9" diameter), port configuration, and horsepower ratings to determine replacement strategyPiping Configurations: Three-pipe vs. four-pipe designs and when each is necessaryInstallation Considerations: Importance of keeping oil equalization lines level (parallel to ground) and using proper mounting spacersEnhanced Vapor Injection (EVI): How EVI technology extends operating envelopes to -40°F for cold climate heat pump applicationsEnergy Efficiency Standards: Meeting IEER, IPLV, and upcoming IVEC standards through strategic tandem useCopeland Mobile App: Features, including parts lookup, resistance specifications, amperage mapping, AI Scout assistant, and technical bulletins Learn about the Copeland Mobile app at https://www.copeland.com/en-us/tools-resources/mobile-apps/copeland-mobile. 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.
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    50 min
  • The Tech That Tried to Beat the Compressor - Short #268

    The Tech That Tried to Beat the Compressor - Short #268
    Dec 2 2025

    In this short podcast episode, Bryan tells the story of the technology that tried to beat the compressor... and still may someday.

    We associate cooling with refrigerant... and all the things that come with it, including compressor noise, oil, recovery machines and tanks, leaks, superheat, and regulations. However, there is a means of providing cooling with two pieces of metal and several semiconductors; current runs through it, and one side becomes cold, and the other side becomes hot. This technology is called thermoelectric cooling, associated with the Peltier effect.

    In 1834, French watchmaker and amateur physicist Jean Charles Athanase Peltier was experimenting with electricity and dissimilar metals. When he joined two wires of different materials and ran current through the junction, one got colder, and the other one got hotter. This phenomenon was named the Peltier effect, and it describes how passing electrical current through two dissimilar conductors causes heat to move from one side to the other, like a tiny reversible heat pump. However, it didn't have any practical use at the time.

    Semiconductors arrived in the mid-1900s, and engineers could make thermoelectric devices strong enough to move meaningful amounts of heat. In the 1960s, NASA even began using the technology in spacecraft for precision temperature control, which was hardy and allowed them to stabilize sensors and electronics in space. We began using them on Earth in some specialized applications, including portable coolers, wine chillers, and CPU coolers in computers.

    However, this technology didn't replace vapor-compression refrigeration due to efficiency constraints and the need to reject heat. Thermoelectric modules are only 5-10% as efficient as vapor-compression systems, and they need heat sinks or fans to give the heat somewhere to go. We've still been pursuing a comfort cooling use of the Peltier effect, and we've gotten closer, but most applications still have the efficiency block. When efficiency isn't a problem, we encounter difficulties with moisture and latent heat removal. Nevertheless, thermoelectric cooling is still making a difference for sensors and in localized cooling applications.

    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.
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    13 min
  • VRF, Ductless and Humidity Control w/ Roman

    VRF, Ductless and Humidity Control w/ Roman
    Nov 27 2025
    In this comprehensive episode, Bryan and Roman dive deep into one of the most challenging topics in modern HVAC: making VRF (Variable Refrigerant Flow) and ductless systems perform effectively in humid climates like Florida. The conversation tackles a common misconception that inverter-driven equipment automatically handles humidity well simply because it can "turn down." Roman emphasizes that successful application of VRF technology in humid environments requires skilled professionals who understand building science, envelope integrity, and proper system sizing. The biggest takeaway? If you're going to err on sizing, undersize rather than oversize - these systems will run longer and maintain better humidity control when properly sized. The hosts explore the three critical factors for dehumidification: runtime, coil temperature, and surface condensation. They explain how traditional inverter systems were programmed for energy efficiency by allowing coils to warm up as they approached the set point, which unfortunately sacrifices latent capacity. Modern systems with active dehumidification capabilities use expansion valve control to "starve" the coil, lowering saturation temperature to around 35-37 degrees while extending runtime. Roman shares his personal experience with a 7,000 BTU unit serving his 700 square foot master bedroom suite, demonstrating how proper application and understanding of equipment capabilities can deliver excellent humidity control without oversizing. The discussion takes a practical turn as Bryan presents a comprehensive troubleshooting checklist for humidity problems, starting with bulk water leaks and progressing through envelope integrity, duct sealing, equipment selection, and pressure balancing. They debunk common "solutions" that actually make problems worse, like adding attic insulation or solar attic fans without addressing root causes. The conversation reveals a counterintuitive truth: reducing sensible load through excessive insulation can worsen humidity problems by reducing equipment runtime. They explain why "active dehumidification" through overcooling isn't true dehumidification, and why another solution - reheat - requires adding sensible heat back to spaces to maintain longer equipment runtime. Topics Covered: VRF and inverter sizing misconceptions - Why undersizing is often better than oversizing in humid climatesThree factors of dehumidification - Runtime, coil temperature, and surface condensation explainedActive dehumidification technology - How expansion valve control creates longer runtime and colder coilsEquipment capacity ratings - Understanding that a "12K" unit may actually perform at 18,000 BTULatent vs. sensible capacity - Why checking engineering specifications is critical for humid climate applicationsVRT (Variable Refrigerant Temperature) - When this energy-saving feature should be disabled in humid climatesFan operation strategies - Why continuous fan operation can worsen humidity problemsDuct and envelope leakage - How pressure imbalances drive moisture problemsSurface condensation - Why vents and ducts sweat and how to prevent itThe overcooling trap - Why lowering the set point creates interstitial space moisture problemsHumidity sensors in thermostats - Understanding what they do (and don't do)Load diversity and zone control - How multiple smaller units can outperform single large systemsReheat strategies - From electric resistance to passive solar gainCommon mistakes - Why attic insulation and solar fans often worsen humidity issuesTroubleshooting checklist - A systematic approach from bulk water to equipment selection 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.
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    1 h et 9 min
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excellent in every way, down to earth, straight forward decent people trying to make their part of the world better by sharing their knowledge and experiences.

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