BACK

#latent

Tech Tips:

Room Sensible Heat & CFM – Advanced Psychrometrics Part 1

This is the first of a three-part series of articles that will dive deep into advanced psychrometrics. The source material for each of these articles may be found in ACCA Manual P Sections 3, 4, and 5. This article is based on information found in Section 3. Psychrometrics is the study of the physical and […]

A Bit of Adiabatic Air Science For Techs – FB Live Video

In this video Bryan talks about Heat (Enthalpy) Adiabatic cooling Latent and Sensible heat Evaporative Cooling Humidity Blower Off Delay

Psychrometrics and the Magic Line – Short #265

In this short podcast episode, Bryan talks about psychrometrics and the magic line inside a messy-looking chart. The psychrometric chart is a key tool for understanding the relationship between air and water. “Psychrometric” comes from the Greek roots for “cold” and “measurement.” As such, a tool called the psychrometer (with paired wet-bulb and dry-bulb […]

The Hidden Cost of Killing Radiant Load – Short #260

In this short podcast, Bryan talks about the hidden cost of killing radiant load, especially when it comes to installing radiant barriers in attics. We sometimes get service calls about ducts sweating when they never used to sweat. If there are no problems with the system (i.e., the refrigerant charge, static pressure, airflow, supply […]

ADAM KICKER
#adiabatic #blower off delay #enthalpy #humidity #latent

Check out our most recent video

How to Evacuate an AC system, Full Vacuum Procedure

Our latest Podcast

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 raw and unfiltered episode, Bryan sits down with Elliot, a senior service tech and newly minted install supervisor, to discuss the realities of working with R-454B refrigerant in the field. What starts as a technical discussion about the new A2L refrigerant quickly evolves into a candid conversation about industry frustrations, manufacturer accountability, and the practical challenges technicians face with the latest refrigerant transition. With four years of hands-on experience, Elliot brings fresh perspectives on everything from charging procedures to equipment reliability issues.

The conversation takes an honest look at the R-454B rollout, which Bryan describes as a massive industry failure. Unlike typical manufacturer talking points, this episode dives into real problems technicians are experiencing: extended charging times, subcooling drift, and equipment component failures. Bryan and Elliot discuss how R-454B systems can take up to an hour to stabilize compared to the 15-20 minutes they were accustomed to with R-410A. This isn’t just an inconvenience—it’s affecting how technicians approach charging procedures and follow-up visits.

The episode also explores theoretical explanations for R-454B’s unusual behavior. Bryan presents two hypotheses about why the refrigerant takes so long to reach equilibrium: either density differences between R-32 and R-1234yf are causing stratification in the condenser, or one component is settling at the top and acting like a non-condensable. While admitting he’s “not a mathy details guy,” Bryan encourages field technicians to investigate these phenomena using thermal imaging cameras and careful observation. This practical, boots-on-the-ground approach to understanding new technology exemplifies the podcast’s commitment to real-world problem-solving.

Beyond technical discussions, the conversation touches on broader industry issues, including the politics behind refrigerant selection, manufacturer warranty support (or lack thereof), and the challenges faced by contractors trying to maintain fair pricing while dealing with new equipment failures. Bryan and Elliot also address the reliability concerns with new A2L safety components like dissipation boards and refrigerant sensors, noting that while failure rates aren’t dramatically higher than other components, they represent additional potential failure points that weren’t previously necessary.

Topics Covered

R-454B Charging Behavior: Extended stabilization times (up to 1 hour vs. 15-20 minutes for R-410A) and subcooling drift over time
Field Charging Strategy: Why technicians are intentionally undercharging slightly and relying more on line length specifications
A2L Safety Components: Dissipation boards and refrigerant leak sensors—their function, failure rates, and nuisance alarms
Refrigerant Stratification Theory: Potential explanations for delayed equilibrium involving density differences and non-condensable behavior
Industry Politics: The R-454B vs. R-32 debate, GWP legislation, and lobbying efforts that shaped current refrigerant standards
Manufacturer Accountability: Warranty support issues, untested components, and the financial burden on contractors
Recovery and Reuse Concerns: Questions about blend consistency when recovering R-454B and tank contamination issues
Future of HVAC: Discussion of heat recovery chillers, secondary fluid systems, and emerging refrigerant-free technologies
Pressure Testing Requirements: New legislation requiring extended pressure tests and improved brazing practices
Practical Field Advice: Using thermal imaging to diagnose condenser behavior and verify proper refrigerant distribution

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.

Search Episodes

An R-454B Ramble w/ Elliot

11/13/2025

Bryan Orr

Psychrometrics and the Magic Line – Short #265

11/11/2025

Bryan Orr