HVAC Glossary of Terms
- A patented sealing process; the most effective, affordable, and viable
method of sealing the central heating and cooling ductwork in your home.
- Annual Fuel Utilization Efficiency, a rating that reflects the efficiency
of a gas furnace in converting fuel to energy. A rating of 80 means that approximately
80 percent of the fuel is utilized to provide warmth to your home, while the
remaining 10 percent escapes as exhaust.
- British Thermal Unit. In scientific terms, it represents the amount of
energy required to raise one pound of water one degree Fahrenheit. One BTU is
the equivalent of the heat given off by a single wooden kitchen match. For your
home, it represents the measure of heat given off when fuel is burned for heating
or the measure of heat extracted from your home for cooling.
- Cubic feet per minute, a standard of airflow measurement. A typical system
produces 400 CFM per ton of air conditioning.
- The output or producing capability of a piece of cooling or heating
equipment. Cooling and heating capacity are normally referred to in BTUs.
- The heart of an air conditioning or heat pump system. It is part
of the outdoor unit that pumps refrigerant. The compressor maintains adequate
pressure to cause refrigerant to flow in sufficient quantities in order to meet
the cooling requirements of the system.
- Located in the outdoor unit, the coil dissipates
heat from the refrigerant, changing the refrigerant from vapor to liquid.
- Found in ductwork, this movable plate opens and closes to control airflow.
Dampers are used effectively in zoning to regulate airflow to certain rooms.
- A furnace that pulls in return air from the top and expels
warm air at the bottom.
- Pipes or channels that carry air throughout your home.
- The coil that is inside your house in a split system. In the
evaporator, refrigerant evaporates and absorbs heat from air passed over the
- A device for the transfer of heat energy from the source to
the conveying medium.
- A furnace that lies on its side, pulling in return air from
one side and expelling warm air from the other.
- A device that injects water vapor into heated air as the air is
expelled from the furnace.
- The amount of moisture in the air. Air conditioners remove moisture
for added comfort.
- Heating Seasonal Performance Factor. Refers to the efficiency of the heating
mode of heat pumps over an entire heating season. The higher the number, the
more efficient the unit.
- Heating, ventilation and air conditioning.
- Integrally Controlled Motor. A specially engineered, variable-speed motor
used in top-of-the-line indoor units. ICM motors are more than 90 percent efficient
versus 60 percent efficiency for conventional motors. Continuous comfort, quiet
operation and ultimate system efficiency are the benefits of the indoor products
graced with the ICM motor.
- A piece of air conditioning and heating equipment in which
all components are located in one cabinet. Used occasionally in residential applications,
the packaged unit is installed either beside or on top of the home.
- A substance that produces a refrigerating effect while expanding
- Set of two copper lines connecting the outdoor unit and the
- Seasonal Energy Efficiency Ratio, a rating that measures the cooling efficiency
of a heat pump or air conditioner. The higher the number, the more efficient
- Refers to a comfort system configuration consisting of components
in two locations. Common examples include an outside unit, such as an air conditioner,
and an indoor unit, such as a furnace and coil.
- A device in a heat pump that reverses the flow of refrigerant
as the system is switched from cooling to heating. Also called a reversing valve
or four-way valve.
- A temperature control device, typically found on a wall inside the
home. It consists of a series of sensors and relays that monitor and control
the functions of a heating and cooling system. Programmable thermostats allow
you to program different levels of comfort for different times of the day.
- A unit of measurement used for determining cooling capacity. One ton is
the equivalent of 12,000 BTUs per hour.
- A furnace that pulls return air in from the bottom and expels
warm air from the top.
- A method of dividing a home into zones, which enables you to control
the amount of comfort provided to each.