HVAC Glossary – What Do All Those Words Mean?

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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. At Michael Bonsby HVAC & Plumbing, we want you to have the best service possible, so we’ve made a list of all the most common HVAC terms you might hear when the serviceman comes to your home!

**Note: you can view even more terms on our HVAC glossary page!**

Air handler – the air handler is the term for the blower fan and heat transfer coil, as well as the housing of those components.

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

Attic vent – your attic vent is a mechanical device used to ventilate an attic space, primarily to reduce heat buildup and moisture condensation.

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 outdoor unit on a split system air conditioner. The compressor puts pressure on the refrigerant in the air conditioner so that it can flow through the system.

Condenser – the condenser 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.

Duct fan – a fan that helps blow air through your ducts. That one was easy.

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 – once a very popular refrigerant, it has been phased out in recent years because of a tendency to harm the environment.

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

HEPA filters – High Efficiency Particulate Arrestance filters. HEPA filters are the most effective air filters available and are commonly found in high-end air cleaners.

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.

We hope this glossary has been helpful! If you have any more questions about HVAC service, or if you need an air conditioner tune up or air conditioner repairs, call Michael Bonsby HVAC & Plumbing today!

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