Tech Tips

Modulation motors are not often seen in residential equipment, but we see them a lot in commercial and industrial applications on many different types of equipment. I see them primarily on larger burners to control the fuel firing rate, but they also control water flow through heating coils, the water level on cooling towers, and […]

This question was submitted on the site in response to the recent GFCI tip. It's a good question with several possible answers. What do you think? Hey Bryan, I have had a few instances where we are firing off a furnace in a new build with a temporary power pole outside with gfci outlets installed […]

When you work on a heat pump system and want to test defrost, you can follow many different test procedures to test the board and sensors. Most involve “forcing” a defrost by shorting out pins on the board or advancing the time of the defrost initiation and installing a factory-provided pin jumper. Lots of pins […]

Have you ever wondered why your old refrigerator never needs service or gauges installed and can run for 30 years that way, maybe only needing an occasional cleaning of the condenser? For crying out loud, utilities are buying these old energy hogs through some programs because they never seem to die. Why do they last […]

This article was written by technician and HVAC School community star Kenneth Casebier. Thanks, Kenneth! When looking at replacing a single-phase A/C motor with an aftermarket motor from your van, there are a few things you should know and pay attention to. First, the factory OEM motor will always be the best option, especially when […]

First, a thermocouple is not a flame rectifier like a modern flame sensor. A thermocouple actually generates a millivolt potential difference when it is heated by a flame—just to get that out of the way for any of you newer techs who are used to modern flame sensors. With higher efficiency gas-fired equipment being the […]

Title: NATE Testing & Review Description: Bryan Orr with HVACRSchool.com will offer a general, technical NATE review from 8am-11:30am and proctor a session of North American Technician Excellence (NATE) technician certification testing in the afternoon from 1pm-5pm. The Review will cover elements of the CORE, Air Conditioning and Heat Pump exams and how the concepts apply […]

Brake horsepower (BHP), motor nameplate HP, and the actual electrical power (watts) a motor will consume are different but related concepts. They can get confusing. So, we will tackle them one at a time. Let us start with simple definitions of work, power, and horsepower. Work = distance in feet x force in pounds, both […]

This is a VERY in-depth look at ACFM vs. SCFM and why it matters to airflow measurement from Steven Mazzoni. Thanks, Steve! Imagine your job is to figure out how fast baseballs were traveling before they hit a sheet-rock wall. The only method you have is to measure the depth of the dent left in […]