HVAC School - For Techs, By Techs

In this short podcast episode, Bryan talks about some tips you can use when working with a multi-position service valve. A service valve will have a line connection, which connects the valve to your line set. You also have a gauge port that you can connect to, a valve stem, and a packing gland nut (directly beneath the valve stem). If your stem is completely back-seated, then your gauge port is co...

In this podcast episode, Bryan and Trevor Matthews from Emerson talk through scroll compressors in commercial refrigeration equipment. Scroll compressors are not a monolith; although they all function similarly, they have different fine details and manufacturing protocols by application. Low-temp, medium-temp, high-temp, and A/C scroll compressors each have unique designs, operating conditions, an...

In this episode, Bryan and Bert talk about soft skills. They also discuss why soft skills are important in highly technical trades. Bert's class defined "soft skills" as communication skills; these can be verbal but may also include body language and how we respond to emotional situations. Bert thinks these skills are some of the most important skills you can develop in the HVAC industry and in li...

In this podcast episode, Bryan and Jim Bergmann talk about gas furnace diagnosis and inspection. They cover the ins and outs of furnace assessment. A gas furnace diagnosis requires a few important measurements, but a solid visual inspection is perhaps even more vital. You'll want to look at the venting and condensate disposal systems. You'll want to make sure the flue gas can escape properly and t...

In this short podcast episode, Bryan talks about the differences between pitot tubes and static pressure probes. He also explains how each one works. People often mix up static pressure probes and pitot tubes. A pitot tube is a tube within a tube, and a static pressure probe is just a tube with holes in the side but not at the end. When we measure static pressure, we're measuring the pressure agai...

In this podcast episode, Bryan and Nathan discuss balancing evaporators in a multi-coil circuit. They specifically focus on using the TXV to do so. When we say "balancing evaporators" in a multi-coil circuit, we're referring to the temperature of the air leaving the system; we are worried about the air keeping the product cool in grocery refrigeration. If everything works correctly, the evaporator...

In this short podcast episode, Bryan discusses the difference between mass flow and volume flow when referring to HVAC equipment processes. When you are confused as to whether you're dealing with mass or volume flow, think about the units. For example, cubic feet per minute (CFM) is a measure of volume  because we're talking about cubic units. We care about the volume when we think about air mixin...

In this episode, Bryan and Sam discuss freezing evaporator coils. They explain why frozen coils happen and how to address them. When the coil's surface temperature drops below freezing (32 degrees), the moisture in the air that condenses on the coil can freeze to the coil. In those situations, your suction saturation will probably be in the mid to high twenties. Generally, freezing evaporators wil...

Mike Klokus and Corey Cruz from Kalos come on the podcast to talk about drain cleaning. They discuss their tips and some best practices. Approximately 50% of the calls in the light commercial division have to do with drains, and drain cleaning is a common PM procedure. The procedure starts off when you pull the panel off the air handler and look in the drain pan. Muck can accumulate in the pan and...

In this short podcast episode, Bryan talks about the differences between single-phase and two-phase refrigeration. This particular episode is about the fundamentals of physics, chemistry, and science in general. When we talk about phases, we're referring to the changes in the states of matter. We typically think of the states of matter as solid, liquid, and gas. In refrigeration systems, the refri...

In this episode, Bryan talks with Peter Capuciati and Bryan Johnson from Bluon. They discuss how refrigerant regulations keep changing and how technicians can make sense of it. We've begun phasing out R-22; the refrigerant can no longer be imported or manufactured in the United States. We can still recover and reclaim R-22, but the recovered refrigerant on the market can't meet the usual demand. R...

In this short podcast episode, Bryan talks about the differences between single-phase and two-phase refrigeration. This particular episode is about the fundamentals of physics, chemistry, and science in general. When we talk about phases, we're referring to the changes in the states of matter. We typically think of the states of matter as solid, liquid, and gas. In refrigeration systems, the refri...

Don Gillis joins us again to talk more about common types of CO2 systems and how they differ

In this episode, we are joined by three people who know a lot about heat pumps and cold weather. We also cover everything from the way technologies have changed, some of the pitfalls to keep away from, and why heat pumps work even in really cold climates nowadays. Chad Gillespie: Chad is a senior manager, part of Mitsubishi Electric's Performance Construction Team. He currently leads a national te...

Trevor Matthews is back and dropping more compressor knowledge on us. This time, he talks about demand cooling and liquid and vapor injection. In low-temperature applications, the discharge temperature would get very high and lead to oil breakdown and thermal overload, so demand cooling is a means of cooling the compressor. Demand cooling injects saturated refrigerant into the compressor body to c...

Don Gillis with Emerson joins us on the podcast to teach us the basics of CO 2 as a refrigerant. He explains how it works and its applications. Carbon dioxide is a colorless, odorless gas that is becoming an important refrigerant for commercial refrigeration (R-744). It is desirable because it has a low critical point and high triple point, so we can use subcritical (below the critical point) and...

Sam Myers of Retrotec joins Bryan and Kaleb on the podcast to discuss building performance. He also answers some of our listeners' questions. Checking airflow is important for building science as well as HVAC. However, "airflow" is vague and can refer to static pressure readings (which isn't actually "airflow" at all), air from whole-home ventilation systems, or CFM per ton. We can also look at to...

The great Ed Janowiak (Jon-Oh-Wok) joins us to talk about what correct airflow really looks like. He also explains how to design for it appropriately. The ACCA design series (Manuals J, S, and D) all go hand in hand to design HVAC systems properly for a given space. Correct airflow will depend on how a technician or designer uses the ACCA design series. When we say "correct airflow," we mean that...

Have you ever heard a compressor that keeps changing in sound as it runs? Trevor with Emerson tells us more about what that is all about and how the digital compressor operates.

Joe and Eric join us, and we have a general conversation about small self-contained refrigeration units, including residential and commercial. Small refrigeration includes self-contained reach-ins and small walk-ins. These units typically use capillary tube metering devices. Some of the biggest failures that occur in small refrigeration systems happen because of dirty condensers and user error (le...

Kaleb, Joe, and Eric join us again to discuss some myths about single-pole contactors. We also cover some weird crankcase heater wiring configurations. When you have a single-pole contactor on a unit with no other resistance crankcase heater attached, the contactor energizes the compressor but is NOT a source of crankcase heat. That myth about single-pole contactors likely stems from a misundersta...

Trevor Matthews with Emerson Canada comes on the podcast once again to talk about electronic expansion valves (also known as EEVs). He explains how they work, what they do, and how to diagnose them. Trevor compares electronic expansion valves to TXVs on steroids; they accomplish similar tasks, but EEVs have faster response times, better accuracy, and can improve system efficiency. The valve operat...

Trevor Matthews from Emerson Canada joins us on the HVAC School podcast again to talk about CoreSense by Emerson. Each CoreSense module has the potential to protect compressors. The technology can detect issues like overheating, short cycling, locked rotor, missing phase, low oil, and more. In short, the goal is to notify the technician or mechanic that something happened; sometimes, the control c...

Alex Meaney from MiTek/Wrightsoft joins us again because he's an awesome trainer and knows a thing or two about how to more out of online education for the trades. During the COVID-19 pandemic, we've seen a dramatic shift from in-person to online education. The transition has been hard on students and educators alike, but there are still ways to make it work. Preparation is the key. Before you ent...