Glossary of common terms


Here you will find an explanation of common terms in the HVAC industry. If you don't see a term listed, contact us and we will happily explain what the item is.

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.

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

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.

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.

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

a device for transferring heat from one medium to another.

a substance used for refrigeration, such as R22 or 410

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

a device for making and breaking an electric circuit

A drier as its name imply is used to remove the moisture from the refrigerant. Sometimes it is also referred to as dehydrator or dryer. It is necessary to remove moisture from the system otherwise it may freeze inside the tube causing the flow of refrigerant to be restricted.

The defrost sensor—also called a defrost bi-metal thermostat—shuts off the defrost heater if the heater gets hot enough to damage the evaporator. ... The defrost mechanism in a refrigerator heats the cooling element (evaporator coil) for a short period of time and melts the frost that has formed on it.

A service valve is a valve used to separate one piece of equipment from another in any system where liquids or gases circulate. Two types of service valves are marketed: the Schrader-type valve and the stem-type service valve.

A high-pressure switch is connected to the discharge, or “high” side of the system to sense discharge pressure. A low-pressure switch is connected to the suction, or “low” side of the system to sense suction pressure. Low pressures can occur in air conditioning systems when the refrigerant has escaped.

A transformer is a device which can increase or decrease the voltage of an alternating current or AC. It is a passive device which transfers electrical energy from one circuit to another. This is achieved through electromagnetic induction.

A draft inducer is a fan that's located inside of your furnace near the heat exchanger. By turning on before your furnace ignites its burners, the draft inducer is able to clear out any combustion gases that might be lingering in the heat exchanger from the previous heating cycle.

The roll out switch is a safety mechanism on your furnace. If the furnace overheats, the roll out switch shuts the furnace down to prevent a fire from starting in your furnace. This safety feature not only protects your home from fire, but also prevents damage to your furnace.

Gas valves are flow control devices used to handle and control the flow of gases such as liquefied petroleum, oxygen, and sour and natural gas.

Condenser Coil is the device in an air conditioner or heat pump system that is one of two coils, the other coil, the evaporator coil, is located indoors while the condenser coil is located outdoors (in a split system). The condenser coil is where the heat is removed from the refrigerant.

A device in a heat pump that reverses the flow of refrigerant as the system switches from cooling to heating.

The HVAC blower motor is the heating and cooling systems component that sends conditioned air from the furnace, heat pump, or air conditioner into the home.

The blower wheel is a component of the blower motor and its job is to move large volumes of air through the duct system.

The air conditioner fan motor drives the AC fan, which blows air in and out of the house. This is important for moving hot air to the outside of the building, as well as blowing cool air through the ductwork and into the rooms.

A suction accumulator is used to prevent liquid refrigerant flood-back to the compressor. Accumulators are commonly used on heat pumps, transport refrigeration systems, low-temperature supermarket refrigeration systems, and in any situation where liquid refrigerant is a concern.