Tech Tips

In residential, most techs and installers size the suction (vapor) and liquid lines to the stubs on the equipment. In larger built-up systems, sizing the suction and liquid lines is rarely the responsibility of the technician. But what happens if we show up to a job where the lines cannot be (reasonably) replaced because the […]

Air changes per hour (ACH/ACPH) simply describes how many times the total quantity of air in a room (or structure) is completely replaced per hour. If you have a 10'x10'x10′ room, the room contains 1000 cubic feet of air. If the supply and return to the room provide a balanced 100 CFM (cubic feet per […]

This tech tip about non-invasive testing comes from a post in the HVAC School Facebook group by Ed Janowiak. Ed is the Manager of HVAC Design Education at ACCA, a longtime friend of HVAC School, and an educator who does a lot of great work for the industry. Thanks, Ed! This past Thursday, I taught […]

Fenestration is a fancy architectural term that means “openings in the outside of the building.” You will see this word a lot when you read ACCA Manual J or when you are doing a Manual J load calculation. Fenestration loads include heat losses and gains through windows, doors, skylights, etc., and they can make up […]

There are many brands and styles of evaporator pressure regulating valves (EPR), but none as common as the Parker/Sporlan SORIT and ORIT valves. Photo Courtesy of Parker/Sporlan The diagram above clearly shows some of the common applications. An EPR or “hold back” valve maintains a set suction line pressure and, therefore, coil temperature. That is […]

I hear the following phrase a lot: It's the amperage that will kill you, not the voltage. While there is truth to the statement, it is sort of like saying, “It's the size of the vehicle, not the speed that kills you when it hits you.” OK, so that's a pretty bad example, but hopefully, […]

The term “short” has become a meaningless phrase in common culture to mean “anything wrong with an electrical device.” In reality, a short circuits refer to a particular fault that can mean one of two things in technical lingo: 1. Any two circuits that are connecting in an undesigned manner. This issue would be the […]

Before I start on this one… At HVAC School, we focus on a wide range of topics. Many of them are very basic. My experience as a trainer for over 20 years has taught me that no matter what I assume others SHOULD know, it doesn't change the fact that they often do not. This […]

In this article, we’ll discuss solving superheat using this diagnostic sheet to help us better understand how it is calculated and from where it is derived. I want to thank Ty Branaman for helping me develop these sheets that will hopefully aid in a better understanding of some of the basic HVAC measurements that both […]