Glossary of common terms

Here you will find an explanation of common terms in the HVAC industry


an appliance fired by gas, oil, or wood in which air or water is heated to be circulated throughout a building in a heating system.

Heat Pump

a device that transfers heat from a colder area to a hotter area by using mechanical energy, as in a refrigerator.

Air Conditioner

a system for controlling the humidity, ventilation, and temperature in a building or vehicle, typically to maintain a cool atmosphere in warm conditions.


An AC or heat pump compressor is the part of an outdoor air conditioner or heat pump that compresses and pumps refrigerant to meet household cooling requirements


A condenser (or AC condenser) is the outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the time of the year. ... The condenser fan is a vital component and circulates the air across the coil to facilitate heat transfer.


a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator.

Hot surface ignitor

The hot surface ignitor (HSI) is the most commonly used electronic ignition system. It works like a light bulb filament, heating up when electricity is passed through it. Most are made from silicon nitride or silicon carbide. The igniter is positioned in the flow of gas entering the burners.

Pilot light

a small gas burner kept continuously burning to light a larger burner when needed, especially on a gas stove or water heater.

Heat exchanger

a device for transferring heat from one medium to another.


a substance used for refrigeration, such as R22 or 410

Circuit Board

a thin rigid board containing an electric circuit; a printed circuit.


a device for making and breaking an electric circuit