Tech Tips

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 […]

Humidifiers are a big part of HVAC systems in dry locations, especially in the winter. I have no experience with them personally because they aren't prevalent at all in Florida. I asked some of the HVAC School contributors to weigh in with some of their top humidifier tips. Thanks to Nathan Perney, Steve Domansky, and […]

This is an internal guide we use at Kalos, and it works for our climate and the type of HVAC equipment we work on. Consult with your company leadership before implementing this or any process. Keep in mind that some of these guidelines are “made up” by me and are only useful in the absence […]

This article was written by HVAC/furnace technician Benoît Mongeau. Thank you, Ben.     High efficiency (or 90%, or condensing) furnaces use a set of two heat exchangers to retrieve more heat from the combustion products than their mid-efficiency counterparts. Because of this, they generate flue gases much colder than those of a mid-efficiency or […]