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Expert Heating and Air Conditioner Definitions

When you want to get the most out of your Heating, Ventilation, and Air Conditioning (HVAC) system, you’ll likely want to be familiar with some of the main HVAC terms. By knowing these terms, you can make a more informed decision next time you need to buy a new HVAC system or determine what needs to be repaired. Since you’ll know more about the main parts of an HVAC system and key terms, you’ll be in a better position to understand a technician’s recommendations.

Air Conditioner

What is an air conditioner? Usually abbreviated to AC or A/C, an air conditioner is a system or appliance used to dehumidify and extract heat from a room or entire facility. 

Air Handler

What is an air handler? Sometimes called air handling units, air handlers refer to an internal part of a heat pump or AC designed to transfer heated or cooled air through a home’s ductwork. Usually, air handlers are relatively large metal boxes, with various HVAC parts located inside them responsible for controlling filtration and airflow.

British Thermal Unit

What is a BTU (British Thermal Unit)? A British Thermal Unit (BTU) refers to a type of heat energy measurement. A single BTU will have enough heat to raise a pound of water by one degree Fahrenheit. When you’re looking for a new heating system or evaluating an old one, keep in mind that higher BTU ratings will mean the system has a greater heating capacity.


What is a compressor? Heat pump and AC compressors are pieces of equipment in a heat pump or AC made to compress the refrigerant and then pump it out to meet a home’s heating and cooling needs.


What is a condenser? A condenser is a unit in an HVAC system designed to hold all of the parts needed for removing heat. You’ll usually find condenser units located outside a home. 

Condenser Coil

What is a condenser coil? Condenser coils are mounted inside a system’s ductwork or air handling unit and are a piece of equipment responsible for heat transfer to air. The coil releases a system’s heat by condensing refrigerant into a liquid.

Condenser Fan

What is a condenser fan? A condenser fan is located near the condenser coil and is responsible for circulating air over it.


What is ductwork? Ducts are made up of specially manufactured plastic, metal, or fiberglass tubing. This tubing connects a home’s air diffusers to its air handler. Ductwork refers to the entire series of ducts within a home.

Electronic Air Purifiers

What is an electronic air purifier? Sometimes called electronic air cleaners or ionizers, electronic air cleaners reduce a home’s airborne contaminants by using filters featuring an electric charge. When air goes through an HVAC system, the ionizer will capture dangerous particles with its filters before the contaminants can recirculate through a home’s air.

Energy Efficiency Ratio

What is an Energy Efficiency Ratio (EER)? Energy Efficiency Ratio (EER) refers to an AC’s ratio of cooling capacity to the power input, with the power input measured in watts. When an AC has a higher EER rating, it will be more efficient than those with lower ratings.


What is ENERGY STAR®? When looking for HVAC equipment with exceptional energy efficiency, you’ll want to look for an ENERGY STAR label. ENERGY STAR is an EPA and U.S. Department of Energy program designed to promote energy efficiency. These labels indicate a piece of HVAC equipment meets or exceeds the federal government’s guidelines surrounding energy-efficient performance. 

Evaporator Coil

What is an evaporator coil? Evaporator coils are parts of heat pumps or AC’s designed to absorb the heat in a house’s air. You can usually find these coils connected to a furnace or placed inside the air handler.

Heat Pump

What is a heat pump? An HVAC unit’s heat pump is made to cool or heat air by moving heat. Over the summer, a heat pump will take heat from inside the house and distribute it outside. In the winter, a heat pump will capture heat from the outside air and then transfer it to the home’s HVAC system.

Packaged Units

What are packaged units? Packaged units contain a home’s cooling and heating system’s in a single outdoor unit.


What is refrigerant? Air conditioners rely on refrigerant, as this chemical will create a cooling effect during vaporization or expansion. Generally, the most common type of refrigerant in residential AC systems is freon, which is made up of stable chlorofluorocarbon gas.

Refrigerant Lines

What are refrigerant lines? An AC’s refrigerant line refers to the two copper lines in an HVAC system designed to connect the indoor evaporator coil with the exterior heat pump or AC.

Seasonal Energy Efficiency Ratio

What is SEER? Seasonal Energy Efficiency Ratio (SEER) is a popular air conditioner energy efficiency rating. If a unit has a higher SEER rating, it will be more efficient.


What is a thermostat? Thermostats are devices responsible for monitoring a home’s temperature. Alongside monitoring temperature, they’ll automatically change a cooling or heating system to ensure a system stays at the level a user sets.

Variable Speed Motor

What is a variable speed motor? A variable-speed motor is a kind of motor made to operate at a wide variety of speeds. Since it can operate at such a broad range, it excels at precisely controlling a home’s cooled and heated air distribution.

Choose Bonney for AC Service and Heater Service Near You

Now that you’re familiar with some of the main HVAC terms, you might be interested in receiving AC repair services near you. If you’re located in the greater Sacramento area, our team at Bonney can help diagnose HVAC problems, make repairs, and perform routine maintenance to ensure your AC runs as efficiently and reliably as possible.  We can even install a new unit if you need us to. Alongside our extensive repair and installation services, we offer several coupons to ensure you get premium service at a cost-effective price. Turn to Bonney for AC service services near you by scheduling an appointment today.