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It’s always good to reaffirm some of the basics of energy, work, and matter. The five rules below are some of the most basic and important. The First Law of Thermodynamics States that energy cannot be created or destroyed. It can only change forms or be transferred from one object to another. If you’d like […]

If you are new to the trade, I’d like to welcome you. Like many skilled trades, the HVAC/R trade has many opportunities and can help you make a good living. We need those of you who are young and new to the trade, and we are grateful to have you. But as a word of […]

Some quick basics: An ohmmeter is used to measure the resistance to electrical flow between two points. The ohmmeter is most commonly used to check continuity. Continuity is not a “measurement” as much as it is a yes/no statement. To say there is continuity is to say that there is a good electrical path between […]

A while back, I had a tech who was having some trouble finding a 35 PSI (2.41 bar) make-on-fall pressure switch. One adjustable switch in the catalog said (SPDT), but he didn’t quite understand what that meant. In that case, it means single-pole, double-throw, and the “double-throw” part means that the switch has terminals in both the […]

  The most common—and often most frustrating—questions that trainers and senior techs get asked sound something like this: “What should my ______ be?” or “My _____ is at ______. Does that sound right?” Usually, when the conversation is over, both the senior and junior techs walk away feeling frustrated because the junior tech just wanted […]

Delta T is the difference in temperature between two points of the same medium. It is commonly used by scientists and engineers to analyze the amount of heat transfer in a system. In general HVAC terms, it is the measurable change in temperature between an air input and air output. However, it could also be […]

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 […]

Let’s start with the basics. Water freezes at 32° Fahrenheit (0° Celsius) at sea level and at atmospheric pressure. When any surface is below that temperature, and the air around it contains moisture, ice/frost will form. You can see how water freezes at the molecular level in the GIF below:   In some situations, ice […]