Heating & Air Conditioning Expert with 25 years of experience

Mon-Fri: 08:00 am-5:00 pm

24h Emergency Service

Call Today 888-628-0691

We're Standing By

Glossary of HVAC Terms Q-Z

HVAC Glossary

HCFC (hydro chlorofluorocarbon) refrigerant, commonly known as Freon. It is primarily used in residential air conditioning systems. It is being phased out due to its higher global warming potential (GWP) and ozone depleting properties. Starting January 1, 2020 R-22 will no longer be produced or imported into the United States.

A refrigerant that is non-ozone depleting that has replaced R-22 as the preferred refrigerant in the USA, Japan and Europe. R-410A works at a higher pressure than R-22 and requires the use of different equipment than with R-22. R-410A is also being slowly phased out in certain areas of the US, with California leading the charge and promising to ban the sale of new R-410A equipment in California by 2023.

A chemical, usually a gas, which can be used in a mechanical system to produce a cooling heat transfer effect while changing the pressure of the refrigerant. Many air conditioning and refrigeration systems use refrigerants which change from gas to liquid and back to a gas during the heating and cooling process. See R-22 and R-410A above.

Refrigerant Lines
Refrigerant lines are the pipes connecting your outdoor air conditioner or heat pump to your indoor evaporator coil.

A grille assembly that covers the opening or end of an air duct on floors walls or ceilings. They can have fixed or adjustable openings.

Relative Humidity
The ratio of the amount of moisture in the air compared to the amount of moisture the air could hold at the current temperature, expressed as a percentage.

Return Air
The air drawn into the heating unit after having been circulated through a room.

A rating that expresses the efficiency of air conditioning equipment throughout an entire average cooling season, including both the hottest and coolest days. It stands for Seasonal Energy Efficiency Ratio. The higher the SEER rating, the more efficient the system.

Single-stage heating
Single-stage heating means a furnace has one level for heat output, regardless of the temperature outside your home.

Split System
The most common type of residential system, it consists of two main components – a compressor and condensing unit installed outdoors, and an air-handler installed indoors.

A temperature-control device, typically found on a wall inside the home. It consists of a series of sensors and relays that monitor and control the functions of a heating and cooling system.

A unit of measure used to describe the cooling capacity of an air conditioning system. One ton of cooling is the amount of heat needed to melt a one-ton block of ice in a 24-hour period.

Two-stage heating
Two-stage heating means a furnace has two levels, high and low, as opposed to a single-stage heating system which only has one level.

Variable-speed motor
A variable-speed motor inside your air handler or air conditioner can run at a wide range of speeds, giving you precise control over the temperature in your home.

A method of providing independent heating or cooling to different areas or rooms within a building or home, typically controlled by separate controls or by opening or closing the vents and ducts in each zone.

Having an issue with your HVAC? Contact the experts at Millian-Aire who don’t need this glossary!

AC & Heating Connect
American Standard Heating & Air Conditioning