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 […]

Double traps are no good. That's the end of this tech tip. Okay, here's some detail: Anytime your drain goes up and down more than once, you have a double trap UNLESS you place an air vent between the two traps that vents ABOVE the drain inlet. The double trap causes drainage issues because air […]

If you are primarily a residential technician working on equipment under 5 tons, there are many similarities between the systems you are used to and 5-20 ton rooftop units common to the light commercial market. There are MANY additional things to consider on larger equipment, and here are just a few. Wash Fresh Air Filters […]