Fan laws and fan curves are a deep subject with a lot of nuance and variation. Just to get our heads around the subject, let's focus on two different types of fans that we see all the time in HVAC: the prop/axial type and the radial/centrifugal type. Centrifugal/Radial As we increase the pressure differential across […]

This article deals heavily with entropy. Entropy is not a simple topic, so we highly recommend checking out HVAC School’s Entropy in Refrigeration and Air Conditioning for some background information. Describing isentropic compression is a daunting endeavor. We all recognize the term compression, and I’m sure most of us can deduce that isentropic has something […]

When I first started in the trade, I used to advise customers with hot attics to install powered attic ventilators (PAVs) to “suck” that hot air out of the attic. It just made sense to me at the time; if the attic is hot, get the hot out! When I started learning more about design, […]