Evaporator temperatures below 32° are common and acceptable in refrigeration; that's why there is a defrost sequence. In a heat pump running in heat mode, it's the same; freezing is a part of the process, and defrost is necessary. In comfort cooling, we can't allow the evaporator to get below 32°, or it will freeze. […]

The chart above is from a Carrier heat pump, and it lists some common accessories. I have heard this common pressure switch (last on the list) called a low-pressure switch (because it opens on fall in pressure) and a high-pressure switch (because it's in the liquid line), but RARELY do I hear it called its […]

Humidifiers are a big part of HVAC systems in dry locations, especially in the winter. I have no experience with them personally because they aren't prevalent at all in Florida. I asked some of the HVAC School contributors to weigh in with some of their top humidifier tips. Thanks to Nathan Perney, Steve Domansky, and […]