Plain-language definitions of the heating and cooling terms you will meet in our guides and in a contractor's quote.
- Air Filter — A mesh or fibrous panel that traps dust and other particles as air passes through your heating or cooling system. A clogged filter restricts airflow, so it should be checked regularly and changed when dirty.
- Air Handler — The indoor unit that moves air through your ductwork. It usually holds the blower fan and the indoor coil, and it works together with the outdoor unit.
- BTU — British Thermal Unit — a measure of heat. For air conditioners, the BTU rating tells you roughly how much heat the unit can remove from a room in an hour. Bigger is not always better; the right size depends on the space.
- Compressor — The part of an air conditioner or heat pump that squeezes refrigerant gas, raising its pressure and temperature so heat can be released outside. It is the heart of the cooling cycle.
- Condenser — The outdoor coil where hot refrigerant releases its heat to the outside air. Keep the area around it clear of leaves, grass, and stored items so air can flow freely.
- Damper — A movable plate inside ductwork that opens or closes to control how much air reaches a room or zone. Dampers are the basic hardware behind zone control.
- Dehumidifier — A device that pulls excess moisture out of indoor air. It helps in damp climates and basements, and it can make a home feel more comfortable at a higher thermostat setting.
- Ductless Mini-Split — A heating and cooling system without ductwork: one outdoor unit connects to one or more indoor units mounted on walls or ceilings, each cooling its own room.
- Ductwork — The network of metal or flexible tubes that carries heated or cooled air from your system to the rooms of your home. Leaks and poor design waste energy.
- Evaporator Coil — The indoor coil where cold refrigerant absorbs heat from your home's air. If it gets dirty or freezes over, cooling suffers.
- Furnace — A heating appliance that warms air — usually by burning gas or using electricity — and pushes it through ductwork to heat a home.
- Heat Exchanger — The part of a furnace where heat from burning fuel transfers to the air that warms your home, without letting combustion gases into that air. A cracked heat exchanger is a serious safety problem.
- Heat Pump — A system that moves heat rather than making it: it pulls heat out of your home to cool it in summer, and pulls heat in from outside air to warm it in winter. One system does both jobs.
- Humidifier — A device that adds moisture to dry indoor air, usually fitted to a heating system so it treats the whole home at once.
- HVAC — Heating, Ventilation, and Air Conditioning — the whole system that keeps a home warm, cool, and ventilated, taken together.
- PTAC — Packaged Terminal Air Conditioner — a self-contained heating and cooling unit installed through an exterior wall, common in hotels, apartments, and offices.
- Refrigerant — The fluid inside an air conditioner or heat pump that carries heat: it evaporates indoors to absorb heat, then condenses outdoors to release it. Handling it requires a licensed technician.
- SEER — Seasonal Energy Efficiency Ratio — a rating of how efficiently an air conditioner uses electricity over a whole cooling season. A higher number generally means lower running costs, but the right choice also depends on your home and climate.
- Thermostat — The wall control that senses room temperature and tells your heating or cooling system when to run. Where it sits — away from drafts, sunlight, and heat sources — affects how well it works.
- Ventilation — The exchange of indoor air with outdoor air, which keeps indoor air fresh and controls moisture and odors. Good ventilation works together with heating and cooling, not against it.
- Zone Control — A setup that heats or cools different parts of a home to different temperatures, using dampers, separate thermostats, or separate indoor units.
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