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richard HVAC/R Evacuation Quiz May 12, 2022, 10:58 pm
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Techs are Under Pressure
The amount of pressure you're under depends on where you live. I live in Florida, so I'm very close to sea level. Therefore, the weight of the atmosphere is exerting exactly 14.7 pounds per square inch (PSIA) of pressure on every surface in every direction. There is no such thing as negative pressure—only pressure lower […]Read more
Why is 240V called "Single-Phase"?
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 […]Read more
Start Capacitor and Inrush Facts & Myths - Part #2
Thought Experiment #3 – The Start Winding Has No “Inrush” with a run capacitor only The name “start winding” is an antiquated term for the single-phase residential industry. It came from the days when CSIR (capacitor start, induction run) motors were still used commonly. In a CSIR motor, the start relay removes the start winding […]Read more