Why is it called single-phase 240 when there are two opposing phases (or legs)? I wondered why we called two 120v opposing legs “single-phase 240” for years. Then someone pointed out to me that a typical “single-phase” pole transformer only has one power leg entering and two coming out. That freaked me out. How can […]

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 surprisingly […]

When I first started in the trade, I used to advise customers with hot attics to install powered attic ventilators (PAVs) to “suck” that hot air out of the attic. It just made sense to me at the time; if the attic is hot, get the hot out! When I started learning more about design, […]