Can a single-phase motor run backward when start and run are swapped? The answer is (generally) yes. Is the motor designed to run backward by simply swapping run and start? The answer is (generally) no, with a few notable exceptions. Before we jump in, this article has two purposes. #1 – it helps you understand […]

If you went to school and learned the “gas laws” early on, you probably thought it seemed LAME. Then, later, things like mass flow rates, airflow conversions, and compression ratios seemed HARD. Well… It's because HVAC is hard if you don't understand the concepts behind the gas laws, even if you never learn to do […]

I recently received a message asking for a discussion of relative humidity (RH), wet-bulb (WB), and dry-bulb (DB). Time and time again, I hear techs say that condensation occurs when “hot meets cold,” which may be true in some cases. However, that is only a shorthand way to describe it and doesn't really address what […]