HVAC School - For Techs, By Techs

In this episode of the HVAC School podcast, host Bryan dives deep into the topic of vacuum in HVAC and refrigeration systems. He addresses two questions from social media about vacuum, expanding them into a comprehensive discussion of best practices, common issues, and techniques for effective vacuum procedures.

Bryan starts by explaining where to ideally locate a vacuum pump when working on a refrigeration system. He emphasizes the importance of pulling from the largest volume locations possible, often at multi-position service valves on the compressor or wherever accessible ports are available. He notes that systems that have...

In this short Q&A podcast episode, Bryan answers a question about drain traps and static pressure. This question was sent by Stephen with The Comfort Squad when he noticed an uptick in nuisance calls on retrofit systems that kept having their secondary drain pans filled.

In negatively pressurized systems (i.e., straight-cool or heat pump units, not gas furnaces), air can pull water back into the drain line. The evaporator coil is under negative pressure because the blower is on top of the evaporator coil.

The rule of thumb for trap depth is that...

In this informative episode, Bryan Orr speaks with Andre Patenaude from Copeland about CO2 refrigeration systems. They dive deep into the unique characteristics and challenges of working with CO2 as a refrigerant, providing valuable insights for HVAC and refrigeration professionals looking to expand their knowledge in this growing field.

Andre explains the reasons behind the increasing adoption of CO2 systems, including regulatory pressures and environmental benefits. He details the peculiarities of CO2 refrigerant, such as its high triple point and lower critical point, which create unique operating conditions not seen in traditional refrigerants. The conversation covers the...

In this short Q&A podcast episode, Bryan answers Kenton's question about how to stop vents from condensating, especially when sealing and insulation don't do the trick.

When approaching a condensation problem, we have to consider the source of moisture and where the condensation is happening. Moisture that builds up on top of the vent comes from attics with a high dew point. (It's not because hot meets cold! Relative humidity and dew point are a lot more important, though hot air is able to hold more moisture.) Warm, moist air with a high dew point hits...

In this episode, Bryan and Max discuss commercial supermarket startup and commissioning with comparisons to residential HVAC work. Max, who has transitioned from residential air conditioning to supermarket refrigeration, shares his insights on the unique challenges and requirements of this specialized field.

The conversation begins by emphasizing the critical importance of safety in supermarket refrigeration work. Unlike residential jobs, technicians often work alone in potentially hazardous environments with high-voltage equipment and large quantities of refrigerant. Hearing protection is stressed as a crucial safety measure due to the extremely loud environments in motor rooms.

Max then...

In this episode, Matthew Taylor joins the podcast to dive deep into the world of pressure-limiting valves and regulators used in refrigeration and air conditioning systems. They explore the intricacies of Maximum Operating Pressure (MOP) expansion valves, Evaporator Pressure Regulators (EPR), and Crankcase Pressure Regulators (CPR), discussing their functions, applications, and differences.

The conversation begins with an explanation of MOP expansion valves, which are commonly used in low-temperature refrigeration applications and air conditioning systems. Matthew describes how these valves work by using a vapor-charged thermal element to limit the suction pressure, protecting compressors from operating outside their...

In this episode of the HVAC podcast, Bryan and Max Johnson from Kalos discuss the critical role of a startup and commissioning technician in the HVAC industry. Max, who has experience in both residential and commercial HVAC, shares his insights on the importance of understanding the scope of work, equipment specifications, and code requirements.

One of the key responsibilities of a startup and commissioning technician is to prevent any costly issues that may arise during the installation process. This includes identifying and addressing potential problems with ductwork, refrigerant charge, electrical wiring, and airflow. A comprehensive checklist ensures...

In this short podcast of the Q&A series, Bryan answers a question about "stubborn old techs" (submitted by Luke via Speakpipe).

In several cases, old-school techs are "being positional," which means they feel that they have a piece of turf to protect; they see challenges to the status quo as a threat. They may want to defend the way that they do and have always done things. Many of these people also have insecurities and have dealt with a lot of frustration and disrespect over the years, but they also have a lot to offer. Younger...

In this episode, Josh Souders from Copeland joins the HVAC School Podcast to discuss modulating and variable capacity technologies in HVAC systems. Josh provides an in-depth look at the different levels of modulation available in residential HVAC equipment, from traditional fixed-speed systems to two-stage, multi-stage, and true variable-speed compressors.

The conversation covers the benefits of modulating systems, including improved energy efficiency, better comfort, and enhanced humidity control. Josh explains how modulating technologies allow systems to more closely match the actual cooling or heating load of a building, reducing temperature swings and providing more consistent comfort. He also...

In this short podcast episode of the Q&A series, Bryan answers a question about testing dehumidifiers (submitted by Steven via Speakpipe). 

Dehumidifiers run air over a cold evaporator coil (to pull moisture out of the air and drain it out) and then reheat it over a condenser coil. The air leaving a dehumidifier is of a higher sensible temperature than the air going in, but there are fewer overall grains of moisture.

To see how well a dehumidifier is working, you will need to know the dehumidifier's rating and have the manufacturer's charts at y...