Tech Tips

This tip comes from market refrigeration and controls technician Kevin Compass. Thanks, Kevin! A little tip when changing liquid cores: If you start pumping them down, begin bypassing discharge gas into the shell to warm it up, push out the remaining liquid, and bring the shell above the dew point so that it doesn't sweat […]

Before the fighting starts about term definitions, let's just settle on using “adjustable drive pulley” and “sheave” interchangeably to describe the belt-driven power transmission device shown above. Second, for the newer tech, you shouldn't be altering these sheaves so that the belt rides lower or higher in them unless you know EXACTLY what you are […]

Grounding is an area of many myths and legends in both the electrical and HVAC fields. This is a short article, and we will briefly cover only a few common myths. For a more detailed explanation, I advise subscribing to Mike Holt's YouTube Channel HERE. Myth – Current Goes to Ground Actually, current (electrons) will […]

What should the delta T (ΔT) be? What do you mean!? 20 degrees, of course! We are referring to the air temperature drop across an air handling unit or evaporator coil in cooling mode. Actually, depending on who you ask, the answer will range between 18-22 degrees Fahrenheit. Heck, I’ve heard some insist that the […]

Do you know how a solenoid valve works? Really? On the surface, I think we all understand how a solenoid valve works. The coil energizes, creating an electromagnet. That temporary magnetism lifts an iron plunger within the valve allowing refrigerant to flow. But is it really that simple? It turns out that the answer isn't […]

I heard a great presentation by Ron Auvil on VAV systems, and it got me thinking… Can you size a commercial system/perform a block load by the number of occupants? Yes!  No, I'm just kidding. That's crazy talk. There is way more to it than that. However, in a commercial environment, while the building's perimeter […]

Knowing how to combine capacitors in series and parallel properly is a great practical field skill to employ when you need to get a customer up and running, but you don't have the exact size. Increasing in size is easy. Just connect in parallel and add the two sizes together. For example, if you needed […]

This article is a quick, real-life diagnosis/find by Kalos Services senior commercial HVAC/R tech Eric Mele. Improper Defrost Timer installation While servicing this display cooler for an unrelated problem, I noticed the defrost timer installed in a way that will almost certainly cause early compressor failure. Because this is a cooler (not a freezer), it […]

Before we jump into the stuff that will make folks angry, let's start with some common ground. Most of us can probably agree that the desired result of education in the trades is: Knowing what you are doing and doing it as safely, efficiently, and correctly as possible. If we can agree that we all […]