The piston (fixed orifice) and TXV (thermostatic expansion valve) are the two most common metering devices in use today, though some modern systems utilize an electronically-controlled metering device called an EEV (electronic expansion valve). It should be noted that there are other types of fixed-orifice metering devices, like capillary tubes; however, their use is not […]

  You've probably heard the famous last words, “Dude, watch this,” before a concussion, burn, shock, broken bones, or some other bodily harm. This phrase has become synonymous with young guys doing something dumb to impress their friends. Technicians have two common phrases that may not lead to bodily harm (although sometimes they might), and […]

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 […]