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Class is in Session: A Glossary of Common HVAC Terms & Acronyms

If you believe your HVAC system is experiencing issues, will you know how to describe the problem to a technician? There is an easier way for homeowners to explain what’s going on than using terms like, “thing-a-ma-jig “ or “what-cha-ma-call-it.”

Our technicians are always happy to help, but they understand that the components and functions of heating and air-conditioning systems are not common knowledge, especially for first-time homeowners.

That’s why we have assembled a list of the most common HVAC terms, acronyms, and their meanings.  We want our customers to speak about their systems with confidence. And, don’t worry- there’s no Pop Quiz at the end. :)


HVAC Terms & Acronyms:

- Annualized Fuel Utilization Efficiency (AFUE): A measure of furnace heating efficiency. The higher the AFUE, the more efficient the furnace.

- BTU: stands for British Thermal Unit. The amount of energy needed to heat up 1 lb of water by 1 degree Fahrenheit.

- Coil: There are typically two HVAC coils in a system—the condenser coil in the outside air conditioning condenser unit and the evaporator coil in the indoor unit. The coils are what increase or decrease the temperature via heat transfer.

- Combined Annual Efficiency (CAE): Combined Annual Efficiency (CAE) is a measure of the amount of heat produced for every dollar of fuel used to heat your home’s air and water. It is used to compare efficiencies of integrated water and space heaters.

- Compressor: 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.

- Condenser: a heat exchange system that removes warm air and transfers it to an external location.

- Controller: the technical device that controls part or all of the system. Often, these devices control the power to your system, and are automatic.

- Damper: An HVAC damper (also called a duct damper) is a movable plate, located in the ductwork, that regulates airflow and redirects it to specific areas of the home

- Duct: the system by which the airflow travels.

- Energy Efficiency Ratio (EER): The ratio of cooling capacity to the power input (in watts). The higher the EER rating, the more efficient the air conditioner.

- Heat Exchanger: A heat exchanger is a heating component that is located in the furnace and transfers heat to the surrounding air, which is then pumped throughout the home.

- HVAC: Heating, Ventilation and Air Conditioning.

- MERV Rating: The Minimum Efficiency Reporting Value (MERV) rating is used to rank the efficiency of air filters

- Refrigerant: A chemical that produces a cooling effect while expanding or vaporizing.

- Seasonal Energy Efficiency Ratio (SEER): Seasonal Energy Efficiency Ratio (SEER) is an energy efficiency rating for air conditioners. The higher the SEER, the more efficient the unit.

- Split system: a heating and cooling system in which certain components are outside the home, while others are inside.

- Ton: Unit of measurement for determining cooling capacity.


With these basic terms, you will begin to have a much better frame of reference for troubleshooting problems with your technician. We know there will still be situations that will not be solved with this short glossary. In those cases, we would be GLADD to come out for a home visit. Please give us a call at 866-830-5444.

About Us

Gladd Heating and Air Conditioning is a family owned and operated company. Gladd team members have service Orange County/South Los Angeles areas

Our goal is to “Simply be the best”. We provide expert, professional and personable service because our technicians are focused on fixing your equipment and not on upselling you with unnecessary repairs or new equipment.


Homeowners Turn To Us Because We Deliver 100% Customer Satisfaction, Guaranteed.

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