HVAC School - For Techs, By Techs

In this short episode, we review the basics of the refrigerant circuit. The standard HVAC refrigeration circuit has four main components: compressor, condenser, metering device, and evaporator. The compressor squeezes refrigerant vapor into a smaller volume by applying lots of pressure. It simultaneously moves and compresses gaseous refrigerant. The more a compressor has to compress a gas, the les...

Jon Bennert from Air Oasis teaches us about PCO and Bi-Polar air purification and how it improves indoor air quality through ionization. Photocatalytic oxidation (PCO) is a technology field that uses catalyst metals, hydration agents, and lights to help remove pollutants from the air. These technologies shine a light source on a photocatalyst metal that reacts with pollutants in the air. These pol...

In today's podcast episode, Eric Mele comes on to talk about reach-in coolers (refrigerators), freezers, and wine coolers with some mindset and technical tips. We mostly discuss self-contained equipment. Coolers are medium-temperature applications, while freezers are low-temperature applications. Wine coolers vary from normal coolers because they have slightly higher temperatures and controlled hu...

Stephen Rardon and Neil Comparetto join the podcast to talk about their headfirst dive into building performance as HVAC techs. They discuss jobs they do, how the transition has been, and important HVAC principles in building performance. Addressing duct leakage can help with indoor air quality and home performance overall, but it can also even help reduce noise. Building performance and HVAC both...

Dick Wirz, author of Commercial Refrigeration for Air Conditioning Technicians , talks to us about refrigerator and freezer defrost strategies. Check out Dick's book HERE . In commercial refrigeration, we deal with much lower evaporator temperatures than residential HVAC. Although an evaporator temperature of 40°F may be commonplace in residential HVAC, you can expect evaporator temperatures from...

In this episode, Bill and Bryan recap the 2018 AHR conference with what they learned and what you can expect to see in the HVAC/R trade in the next year. There were 2100 exhibitors who gave demonstrations and discussed products. AHR shows the real scope of the HVAC/R industry, and it is an excellent opportunity to learn more about the trade and do some networking. At the AHR conference, there were...

In today's podcast episode, Bryan talks to west-coast commercial tech Jim Loring about pneumatic controls and variable air volume (VAV) systems. People sometimes confuse pneumatics and hydraulics. Hydraulics use liquid to provide pressure; conversely, pneumatics use air to provide pressure. Pneumatic controls use a bit more energy than other controls, but they are less costly all around. Nowadays,...

Jeremy Smith goes over floating suction and floating head refrigeration strategies. He also talks a bit more about low-ambient equipment operation. Floating suction controls developed when we started using low-pressure controls on rack refrigeration. As the electronics advanced, we developed controls that could control temperature, which impacts pressure as well. Nowadays, controls can cross data...

Bryan talks with Jesse and Nathan about setting up dehumidification for residential equipment in general. They also discuss some of the required and recommended settings on an Ecobee thermostat. On typical single-stage residential equipment, dehumidification works based on CFM per ton. We control humidity by dropping the CFM across the indoor coil and extending runtime. However, as you cool the ai...

In this episode, we cover the skills and traits needed to be the best residential service techs you can be. We follow up on the last episode's tips for getting a raise and discuss how to become more valuable as an employee. All good service techs clearly have to be able to repair and maintain systems well. Commercial and residential techs need to demonstrate mechanical aptitude. However, soft skil...

As we ring in the new year, this episode focuses on how people in the HVAC/R trade can get a raise, promotion, or bonus without facing rejection or sounding selfish. Before you think about asking for a raise or promotion, evaluate your company. Is your company pragmatic? Does the company refuse to address conflict or let tempers run high? Do your leaders care about making decisions logically and p...

In this podcast episode, we discuss power distribution and some practical tips about three-phase, single-phase, and split-phase power. The power company generates three-phase power; a power pole transformer typically has three current-carrying conductors. Each phase of power runs at 60 Hz and generates a sine wave. That sine wave peaks and valleys in a wavy formation. Power is generated in a rotat...

Learn about large-scale desiccant dehumidification from the expert, Tom Peterson. Tom works with CDI (Climate By Design International). Dehumidification has several different methods and applications. Cooling is the most basic of those methods, but it has its limitations. For example, dehumidification by cooling may leave moisture on the coil and lead to freezing. Desiccant dehumidification can re...

Carter tells us why compression ratio is important, what it means, why it changes so much on heat pump systems, and the effect it has on system operation. We also talk a bit more about heat pumps and their unique challenges beyond compression ratio. Compression ratio is a comparison of discharge pressure to suction pressure. A ratio of 3:1 indicates that the discharge pressure is three times highe...

In today's podcast, Bryan talks about voltage (volts) and resistance (ohms), specifically using a voltmeter and an ohmmeter for diagnosis. We also discuss voltage drop. In many cases, Ohm's law is impractical for field usage because of the additional resistance from inductive reactance. We also don't typically measure impedance and only care about resistance on the windings. However, Ohm's law is...

Jamie Kitchen from Danfoss talks all about variable-speed motor technology. He discusses why those motors exist, what they do, and how to think differently about the future of HVAC/R. Most techs think about variable-speed motors as the X13 and ECM blowers in residential applications. Those motors can adjust their performance based on ambient temperatures and moisture levels. So, variable performan...

Jack Rise returns to the podcast to share some duct design facts with us and talk about his Manual D book on the ACCA website. Before we can even start thinking about duct design, we need to think about the total effective length; even before that, we also need to think about finding the critical path. The critical path is the path with the greatest resistance to airflow (from the return to supply...

Nate Adams joins the podcast to describe the method behind his madness of removing gas meters and installing heat pumps in Ohio. Nate is in the home performance business, and he focuses on its intersection with the HVAC industry We typically find heat pumps in milder climates, so removing gas meters and replacing them with heat pumps is a bold move in cold climates. However, high-performance heat...

Bill Johnson is one of the great educators and writers of our time in HVAC/R. In this podcast episode, he shares some information about his career and some of his top tips on keeping systems leak-free. Bill began his work on leak-free solutions by using Glyptal on centrifugal compressors. The Glyptal would harden around leaks and seal them up. Nowadays, this is an ineffective approach to sealing l...

Jim takes us all the way through the history of furnaces, from the Stone Age when he was a child to modern modulating condensing types. The goal of a furnace is to move heat, so a furnace uses heat exchangers to facilitate heat transfer. Furnaces have primary and secondary air. The primary air goes through the burner, and the secondary air goes around the flame and is pulled in around the heat exc...

This podcast episode on electrical circuits is a class recording. In it, Bryan discusses transformers, ground, common, and line vs. load sides of a circuit. Transformers use induction to pass alternating current signals to electrical appliances. Alternating currents (AC circuits) are tricky because the current switches direction each time. Therefore, the current flow is difficult to visualize beca...

In HVAC work, we deal with quite a few electrical components. But where does electricity come from? Why do electrons move? In this podcast episode, we talk about differential charges, sine waves, and some voltage measurement basics. A large chunk of electrical theory is centered on electron movement. We get electrons to move with differentials in charges or energy states. Nature tends towards equi...

Do you think of the building envelope as a duct? Do you test it? In this podcast episode, Joe Medosh talks to us about envelope testing and why it's the future of building health and comfort. The building envelope is the largest duct in the entire home. However, so many HVAC techs forget about it; they attempt to optimize comfort in the HVAC system and ducts, not the home itself. Techs use Manual...

Ductless expert Jesse Claerbout talks about his best maintenance practices for ductless air conditioners and heat pumps. This episode is part 2 of the two-part series.  Ductless outdoor units tend to have clean condensing coils. The only real issues are grass clippings (and cottonwood, in some locations). which typically don't affect performance too sharply. Jesse likes to clean outdoor units with...

Ductless expert Jesse Claerbout talks about his best practices for maintaining ductless air conditioners and heat pumps. This episode is part 1 out of 2. Ductless maintenance can be a bit more extensive than regular split system maintenance. Ductless filters are plastic; they are not high-MERV and can simply be washed off with water. Customers can clean their own filters with nothing but water fro...