What Do All Those Words Mean?

If someone asked you to locate the air handler on your air conditioner, what would you say? How about if they asked you what the BTU output is? There are a lot of industry specific terms in the HVAC world, and things like air conditioner service can be a little intimidating if you don’t know what those words mean.

Air handler the air handler is the term for the blower fan and heat transfer coil, as well as the housing of those components typically found inside your home in a closet, utility area or the attic.

Attic fan an attic fan is a fan mounted on your attic wall that exhausts warm attic air to the outside.

Blower fan the blower fan moves air from the return duct over the coil / heat exchanger. The circulated air is then heated or cooled and sent through the supply duct, past the dampers and into your home.

British thermal unit (BTU) most furnaces and heating systems measure their heating output in terms of BTUs. One BTU is the amount of heat required to raise the temperature of one lb of water by one degree – this is equal to 252 calories.

Compressor this is the heart of the unit on a split system air conditioner typically contained within the condenser. The compressor puts pressure on the refrigerant in the air conditioner so that it can flow through the system.

Condenser the condenser or outdoor unit is a device in an air conditioner or heat pump where the refrigerant condenses from a gas into a liquid when it is depressurized or cooled.

Dampers devices that change the way air flows through your ducts. Dampers can be usually be controlled, either manually or automatically if you have a zoned system.

Ducts round or rectangular tubes, usually made of sheet metal, fiberglass board or a flexible plastic / wire composite. Your ducts carry the conditioned air through your home.

Forced air HVAC system – any HVAC system that uses a fan to blow conditioned air through air channels or ducts.

Freon – a trade name for a specific refrigerant or coolant used within air conditioning systems. The Environmental Protection Agency ordered the phasing out of Freon R-22 because of its ozone-depleting properties and in its place is a new, more environmentally friendly coolant called R-410A. The new coolant, though, won’t work with A/C units manufactured before 2010.

Fuel efficiency – this refers to the amount of heat produced by your heating system vs. how much fuel you burn.

Heat PumpA heat pump works on the basic principle that the sun’s heat is always in the air, even in cold air. A heat pump extracts this heat from the outside air and transfers it into the interior of the house by way of the house’s internal duct work. It is a major energy saver when running your heat. If the outside temperature drops too low to extract heat from it, a backup heat strip will power on.

HEPA filters High Efficiency Particulate Air filters. HEPA filters are the most effective air filters available. The US Centers for Disease Control defines a HEPA filter as an air filter that removes more than 99.97% of particles 0.3 microns or larger at a specified flow rate of air.

Packaged air conditioner – air conditioner that had the evaporator, compressor and condenser all in the same unit.

Plenum any air compartment connected to a duct or ducts.

Return air “used” air that is returning to your HVAC system to be reconditioned.

Return duct a duct through which return air goes to be cycled back through your HVAC system.

Seasonal energy efficiency ratio (SEER) a measure of efficiency for air conditioners and heat pumps. Specifically, the average BTUs of cooling delivered for every watt-hour of electricity used.

Split system air conditioner – an air conditioner that houses the different components in separate units.

Supply duct – duct through which conditioned air flows into your room

Ton (in AC terms) one unit of cooling capacity or 12,000 BTU per hour

Zone (in AC terms) an area within your home that is individually heated or cooled. A zone has its own thermostat for individual temperature control.

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