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 […]

Belly band crankcase heater When I first started in the trade as an apprentice, we worked on many Trane heat pumps that used crankcase heaters. These crankcase heaters slid into the compressor sump on the big orange Tyler reciprocating compressors. They looked like the one in the picture below. It was very common for these […]

This website is for professional HVAC techs and those actively learning to become professional HVAC techs, not DIY homeowners. I feel like that needed to be said before I state these seemingly obvious facts, but these very obvious facts are so commonly mistaken that it needs to be covered. Take a look at the two […]