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Tech Tips:

How Attic Designs Need to Account for Heat and Moisture

This tech tip was heavily inspired by one aspect of Rick Sims’s 2021 HVACR Training Symposium session titled “Conductsation.” The entire presentation is worth a watch, but the advice in “Conductsation” and this tech tip are tailored to hot, humid climates. The contents of this tech tip may NOT work for colder climates. Dr. Allison […]

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HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

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

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