Category: Tech Tips

The general law of perfect gas is a combination of Boyle’s and Charles’s laws. Each of those laws neglected pressure, temperature, or volume in their formulas. The law of perfect gas combines the two, clearly establishing the relationship between all three variables and giving those laws a much more practical use in our field. We […]

We’ll never run out of content to discuss as long as thermostatic expansion valves exist. Deal with it. Today, we’re going to focus on the powerheads of TXVs. This article will focus on what the powerheads do, how they work, and some basic troubleshooting procedures involving TXV powerheads.   What is a powerhead, and where […]

This article was submitted by Genry Garcia of Comfort Dynamics, Inc. It is the second part of his series on zonal pressure diagnostics. Thanks, Genry!   In Part 1 of this series, we outlined the basic understanding of ZPD—what it means and what it does. Most importantly, we showed how an effort to simplify a […]

DISCLAIMER: HVAC School is NOT an official OSHA safety training resource! Although we provide safety tips in good faith, our website is not a substitute for safety training from an authorized OSHA training source.   Although we primarily work with our hands, our eyes are one of our most valuable assets in the industry. After […]

DISCLAIMER: HVAC School is NOT an official OSHA safety training resource! Although we provide safety tips in good faith, our website is not a substitute for safety training from an authorized OSHA training source.   We have already touched on safety in previous tech tip features about recovery tanks, as recovering refrigerant can be a […]

John Dalton was an English chemist and physicist born in 1766. He was born into a Quaker family of tradesmen, though he and his brother became teachers early in life. His family bought a Quaker school in Kendal, where he and his brother taught around 60 students.  Dalton separated from the church as a young […]

DISCLAIMER: HVAC School is NOT an official OSHA safety training resource! Although we provide safety tips in good faith, our website is not a substitute for safety training from an authorized OSHA training source.   Many things may deter people from working in the HVAC industry. Perhaps surprisingly, exposure to heights could be the deal-breaker. […]

Jacques Charles was a French physicist (and a real looker based on that photo) born in 1746. Little is known about his educational and family background, but he began his career as a clerk at the Ministry of Finance in Paris. After a short time as a financial clerk, he began focusing on science. The […]

Why Defrost? Let's start with the basics and move on from there. Defrost is necessary when the coil temperature drops below 32°F. Defrost can be as simple as turning the compressor off for a period of time or as elaborate as reversing the flow of refrigerant for the whole system or for just parts of […]