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Basic HVAC Vocabulary Terms for Homeowners

The HVAC industry uses terms and vocabulary that may not be easily understood by the average homeowner. In fact, there are probably a lot of people who don’t even know that HVAC itself stands for Heating, Air Conditioning, and Ventilation. Hopefully this glossary list will help you understand are some of the more common HVAC vocabulary terms used regularly in the industry so you can become more educated about the heating and cooling system in your home.


AFUE – an acronym for Annual Fuel Utilization Efficiency. It measures how efficiently your furnace can use fuel. Find out more here.

Air cleaner (air purifier) – an installed system that removes allergens and other particles out of the heated or cooled indoor air.  Learn more here. 

BTU – term used to define heating capacity of a furnace. BTU stands for British Thermal Unit, and is the amount of heat required to raise a pound of water by one degree Fahrenheit.

Capacitor – The run capacitor provides extra energy to the condenser fan motor and blower motor when they are in operation.

Compressor – the part of the air conditioner unit that is located outdoors. It compresses, circulates, and pumps refrigerant to cool the air.

Condenser coil – (outdoor coil) The outdoor part of the heat pump or air conditioner that releases or collects heat.

Condensing unit – the outdoor equipment that consists of the compressor, condenser coils, a fan motor, and their controls.

Damper – plates that can be adjusted to restrict air flow in the ductwork

ENERGY STAR® – HVAC products that meet or exceed EPA guidelines for high-efficiency.

Evaporator Coil – the part of the air conditioner or heat pump that is located indoors and attaches to the furnace or inside the air handler. It exchanges heat, working with the air conditioner in summer and furnace in winter.  Sometimes known as the indoor coil.

Heat Exchanger – Located inside the furnace, it transfers heat through the ductwork and vents potentially harmful combustion byproducts out of the home.

Heat Pump – a HVAC unit that heats or cools by moving heat. It removes heat from the indoors out in the summer, and reverses to bring heat inside from the outdoors in the winter.

HFPF – HSPF stands for Heating Seasonal Performance Factor, and is used to measure the heating efficiency of a heat pump.

HVAC – abbreviation for Heating, Air Conditioning, and Ventilation

MERV Rating – This acronym for “Minimum Efficiency Reporting Value” refers to the size of the holes in a filter that air can pass through. Higher MERV ratings mean smaller holes in the filter that can trap more particles. You can find out more here.

NATE – North American Technician Excellence – the only certification program for HVAC professionals that is supported by the entire industry. NATE certification is a useful place to start to help determine which HVAC technician to choose for the job.

R-22 – a refrigerant (also known as Freon) that is found in older air conditioning and heat pump systems. Since it depletes the ozone layer, R-22 has been banned for use in any HVAC equipment manufactured after January 1, 2010; after 2020, manufacturers will no longer be able to produce R-22 for use with heat pumps and air conditioners. Learn more here.

Refrigerant – a chemical substance used with most air conditioning units that helps cool the air.

Thermostat – A mechanism that detects temperature levels to activate and shut off your furnace or air conditioner. Learn about the benefits of remote access thermostats here.

SEER – Seasonal Energy Efficiency Ratio rates energy performance. A high SEER rating means higher energy performance and savings.

Zones – refers to separate rooms or areas in the home.  Some thermostats can control the heating, cooling, and humidity in different zones in your house.

For other definitions and further details, please visit the Carrier website.