Do you feel like you’re trying to understand a foreign language when learning about your home’s heating, ventilation, and cooling (HVAC) systems? Here is a glossary of common terms to help.
AFUE
The Annual Fuel Utilization Efficiency is a measurement of a heating system’s efficiency in turning fuel into energy. An 85 percent AFUE rating means that 85 percent of the fuel the system uses is turned into energy.
Air handler
The indoor part of a split heating and/or cooling system that circulates air.
Boiler
A boiler is part of a heating system that heats water to provide steam or hot water for heating. The steam or heated water is distributed through pipes to radiators or baseboards.
BTU
Stands for British Thermal Unit. It is a measurement of heat energy. For heating systems, the BTU number measures the heat output; for air conditioning systems, BTU measures the cooling capacity.
Central air conditioning
A system where air is cooled at a central location and then distributed throughout the house using ductwork. Most residential central air conditioning systems are split systems, so that part of the system is indoor and part is outdoor.
Condenser
In a central air conditioning split system, this is the part of the unit that is outside the home. The condenser’s job is to release the heat accumulated by the indoor portion of the air conditioner.
Condensate line
As your air conditioners’ condenser cools heated air, it produces condensation. This water drips down a through a drain line. The condensate line can get clogged, causing water to overflow.
Ductless mini-split
These cooling systems have indoor and outdoor units, but do not require ducting. Single-zone systems are designed for one area and have one indoor air handler and one outdoor condenser unit. Some ductless mini-split systems let you have up to four indoor units for cooling multiple areas in your home.
Ductwork
The system of ducts (metal or plastic) that distribute air from your central heating or cooling system throughout your house.
Evaporative cooler
Also known as a swamp cooler, works by cooling air through the evaporation of water. This type of cooling works best when the humidity is 60% or less, such as in the southwestern U.S., where the air is hot and dry.
Evaporator coil
In a central air conditioning system, this resides indoors with either the furnace or air handler. It holds the chilled refrigerant that is used to draw out the heat from the air in your home.
Furnace
A heating system that heats air and distributes it through the house using ducts. Often combined with central air conditioning.
HVAC
Stands for heating, ventilation, and air conditioning. This term is typically used to describe home heating and cooling systems.
Heat pump
Handles both heating and cooling. Heat pumps transfer heat between your home and the outside to provide both heating and cooling. They work best in moderate climates where temperatures do not regularly fall below freezing.
Packaged system
Also called an all-in-one system. All parts of the system are contained in one outdoor unit that is usually installed on a roof or next to the home on a slab.
Refrigerant
Used in an air conditioning system to absorb heat from indoor air.
R-22 refrigerant
Also called Freon. The production and use of R-22 is being phased out, as it depletes ozone. Other, more environmentally friendly types of refrigerant are replacing R-22.
SEER/SEER2
Seasonal Energy Efficiency Ratio 2 measures the efficiency of heating and air conditioning systems. A higher SEER/SEER2 rating means that the system is more efficient.
Split system
The most common type of residential HVAC system, it has two main components: an indoor component (the air handler), and an outdoor one (the condenser).
Swamp cooler
See evaporative cooler.
