First, a thermocouple is not a flame rectifier like a modern flame sensor. A thermocouple actually generates a millivolt potential difference when it is heated by a flame—just to get that out of the way for any of you newer techs who are used to modern flame sensors. With higher efficiency gas-fired equipment being the […]

Probably the most popular measurement method for indirect airflow readings is total external static pressure (TESP). A dual-port manometer or two Bluetooth single-port manometers are essential to the HVAC technician toolbag. Here’s a quick review of TESP, why it’s important, and how to make the measurements. TESP is a pressure reading of the “balloon” pressure […]

Compressibility is the ability of a substance to be squeezed into a smaller volume. It is the change in volume and increase in density that results from an increase in pressure. The subject of compression should be familiar to HVAC techs. After the return air passes over the boiling refrigerant in the evaporator coils, the […]