Posted by: Valley Services HVAC | December 11, 2009

HVAC Glossary, Furnace Terms and Abbreviations

Hello there.  This is an installation to our Heating and Cooling seminar that I think is necessary because there are some HVAC (Heating, Ventilation, and Air Conditioning) words, abbreviations, and terms that not everyone understands (such as myself).  So we are going to learn together.  I will just pick a few important ones and will have a more detailed list of terms and definitions on the Valley Services website.

There are some pretty simple words and abbreviations that once you read this you will know a great deal more about your furnace and air conditioning and how to maintain them!


AC thermostat furnace

1.  Air Conditioner     2.   Evaporator Coil       3.   Furnace        4.     Air Cleaner         5.   Thermostat

Air Handling Unit (AHU) – AHU refers to the equipment that includes a blower or fan, heating and/or cooling coils, and related equipment such as controls, condensate drain pans, and air filters. Does not include ductwork, registers or grilles, or boilers and chillers.

AFUE – Annual Fuel Utilization Efficiency – This percentage represents the furnaces heating efficiency.  The higher the percentage, the more efficient the furnace.  Over time, your furnace becomes less and less efficient.  Maintaining your furnace annually can increase the efficiency and life of your furnace.


BTU – British Thermal Unit – This is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. When a technician sizes up your house for a furnace/air conditioner install, that would control the amount of Btus that your furnace would need to put out.

Freon – a general term for a group of simple hydrocarbons, used as refrigerants.

HEPA Filtration – high efficiency particulate air – high efficiency filter which removes 99.97% of all microns which one would normally breathe into lungs.  Removes tobacco smoke, dust, allergens, dust mite feces, and other pollutants that can cause one to get sick.

hepa filter diagram

HVAC – like I said above, HVAC stands for Heating, Ventilation, and Air Conditioning.

R-22 –  common, old refrigerant for heat pumps and air conditioners, a greenhouse gas, these hydrochlorofluorocarbons depletes the ozone, it is being phased out by January 1, 2010 and R-410A will be used instead.

R-410A – newer, safer refrigerant used in heat pumps and air conditioners, does not deplete ozone if it leaks out of system.

SEER – Seasonal Energy Efficiency Rating – This is a measurement of the efficiency of cooling products.  The higher the SEER, the more efficient the cooling product.

Hope this increases your knowledge of the HVAC terms and how the system in your home works.

If there are other questions you have, visit the FAQ Page, or email

Thanks again!



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