Riteway Heating & Air Conditioning - Terms

Heating and air conditioning terms can be quite technical and confusing. So we have created a list below of the main terms that you may come across

Add On Heat Pump

Installing a heat pump in conjunction with an existing fossil fuel furnace. The result is a dual fuel system.

Advanced Reciprocating Compressor

Type of compressor that uses a more efficient process for compressing refrigerant for better cooling efficiency.


Abbreviation for Annual Fuel Utilization Efficiency. Indicated as a percentage, your furnace’s AFUE measures how efficiently your furnace is converting energy to heat. The U.S. government minimum AFUE furnace rating is 78%, which means that 78% of the fuel used is warming your home, while the remaining 22% is exhausted out the flue.

Air Change

The amount of air required to completely replace the air in a room or building; not to be confused with recalculated air.

Air Diffuser

Air distribution outlet or grille designed to direct airflow into desired patterns.

Air handler

The part of a heat pump system or central air conditioning that's indoors and pushes heating or cooled air through your home; an air handler is usually a blower and coil.


The distribution or movement of air.

Balance Point

The lowest outdoor temperature at which the refrigeration cycle of a heat pump will supply the heating requirements without the aid of a supplementary heat source.

Blower (Fan)

An air handling device for moving air in a distribution system.


British Thermal Unit. One BTU equals the amount of heat needed to raise 1 pound of water 1° F (approximately the amount of heat produced by a wooden kitchen match). For heating, a BTU measures the heat given off when fuel is burned. For cooling, it measures the amount of heat extracted from your home.


British Thermal Units per Hour. Usually expressed as capacity of heat moved per hour for your equipment size.


Combined Annual Efficiency. CAE is the amount of heat produced per dollar of fuel consumed for heating of your home and water.


How effectively a heating or cooling system can heat or cool a specified space. For heating, this is usually expressed in BTU’s. For cooling, it is usually given in tons.


Amount of refrigerant placed in a refrigerating unit.

Comfort Zone

The range of temperatures, humidifies and air velocities at which the greatest percentage of people feel comfortable.


Part of a split system heat pump or air conditioner’s outdoor unit that controls the pressure applied to the refrigerant, necessary for taking in heat to warm your home or getting rid of heat to keep your home cool.

Condenser Coil

A part of your heating and cooling system that's located outside, during the cooling cycle the condenser coil helps cool the refrigerant which removes heat from your home. The coil should be clean to operate at full potential.

Condensing Unit

Part of a refrigerating mechanism which pumps vaporized refrigerant from the evaporator, compresses it, liquefies it in the condenser and returns it to the refrigerant control. The outdoor portion of a split system air conditioner contains the compressor and outdoor coil.


A type of "valve" used in ductwork that opens or closes to control airflow. Used in zoning to control the amount of warm or cold air entering certain areas of your home

Defrost Cycle

The process of removing ice or frost buildup from the outdoor coil during the heating season.


The reduction of water vapor in air by cooling the air below the dew point; removal of water vapor from air by chemical means, refrigeration, etc.


A type of furnace that takes cool air from the top and blows warm air to the bottom - common when your furnace must be located in a second-floor closet or utility area


A pipe or closed conduit made of sheet metal, fiberglass board, or other suitable material used for conducting air to and from an air handling unit.


The pipes that move air from your heating and air conditioning system to the air vents in each room.

Electronic Air Cleaner (EAC)

A filter that uses electricity to create a slight magnetic charge to help collect smaller particles. The EAC then draws tiny particles that are magnetized, such as viruses and bacteria, to a collector plate to remove them from the indoor air in your home.

Emergency Heat (Supplementary Electric Heat)

The back up electric heat built into a heat pump system. The same as an auxiliary heater, except it is used exclusively as the heat source when the heat pump needs repair.

Evaporator Coil

A part of your heating and air conditioning system located in the air handler inside the house. The evaporator coil cools and dehumidifies the air by converting liquid refrigerant into a gas, which absorbs the heat from the air as it passes over the coil. The warmest refrigerant is then carried through a tube to the outdoor unit (condenser coil).

Fan Coil

An indoor component of a heat pump system, used in place of a furnace, to provide additional heating on cold days when the heat pump does not provide adequate heating.


A device for removing dust particles from air or unwanted elements from liquids.

Fresh Vent

Upgrade available for your heating and air conditioning system that mixes fresh, filtered air into your home at a controlled rate. The introduction of a controlled amount of fresh air creates a positive effect on indoor air quality. The FreshVent control also helps circulate air flow in each room to reduce temperature difference.


That part of an environmental system which converts gas, oil, electricity or other fuel into heat for distribution within a structure.

Heat Exchanger

A part of your heating and air conditioning system located in the furnace; the heat exchanger transfers heat from the burners to the surrounding air, and then the blower forces it through the ductwork to heat your home.

Heat Gain

The amount of heat gained, measured in BTU's, from a space to be conditioned, at the local summer outdoor design temperature and a specified indoor design condition.

Heat Loss

The amount of heat lost, measured in BTU's from a space to be conditioned, at the local winter outdoor design temperature and a specified indoor design condition.

Heat Pump

A unit located outdoors that looks similar to an air conditioner but which can heat or cool the air in your house by changing the direction of the refrigerant flow.

Horizontal Furnace

A type of furnace most often installed in attics or crawl spaces. The furnace is installed on its side and draws air in from one side, heats it and emits warm air out the opposite side.


Heating Seasonal Performance Factor; The total heating output of a heat pump during its normal annual usage period for heating divided by the total electric power input in watt-hours during the same period. The HSPF measures a heat pump's heating efficiency. The higher the HSPF measure, the more efficient the heat pump. The US government has established a minimum 6.8% HSPF.


A part of your heating and air conditioning system that adds moisture to heating air as it moves from the furnace into the ductwork and then throughout your house. The added moisture a humidifier provides can help preserve your furnishings and lessen static electricity. Humidistat A device designed to regulate humidity input by reacting to changes in the moisture content of the air.


Heating, Ventilation, and Air Conditioning.

Indoor Coil

Refrigerant containing portion of a fan coil unit similar to a car radiator, typically made of several rows of copper tubing with aluminum fins.

Indoor Unit

This is usually located inside the house and contains the indoor coil, fan, motor, and filtering device, sometimes called the air handler.


Air flow inward into a space through walls, leaks around doors and windows or through the building materials used in the structure.

Load Estimate

A series of studies performed to determine the heating or cooling requirements of your home. An energy load analysis uses information such as the square footage of your home, window and door areas, insulation quality and local climate to determine the heating and cooling capacity needed by your furnace, heat pump or air conditioner.

Matched System

A heating and cooling system comprised of products that have been certified to perform at promised comfort and efficiency levels when used together, and used according to design and engineering specifications.

Operating Cost

The cost of running your heating and air conditioning system, day-to-day, based on energy use.

Outdoor Coil

Refrigerant containing portion of a fan coil unit similar to a car radiator, typically made of several rows of copper tubing with aluminum fins.

Payback Analysis

Overall measure of the efficiency and value of your home comfort system. By combining your purchase price and ongoing operating costs, a payback analysis determines the number of years required before monthly energy savings offset the purchase price.

Puron™ Refrigerant

An environmentally-sound refrigerant specially designed to protect the ozone layer of the earth. Puron has been approved by the US Environmental Protection Agency as a replacement for Freon 22, which must be phased out, along with all ozone depleting refrigerants, by federal law in the next few years.

Reciprocating Compressor

A type of compressor used in air conditioners that compress refrigerant by using a type of piston action.


The practice of returning used refrigerant to the manufacturer for disposal or reuse.


The practice of removing, cleaning and reusing refrigerant.


The name for the chemical used inside heat pumps and air conditioning units. The refrigerant is used to absorb heat and move it another area while being pumped through the system. It absorbs heat in evaporator by change of state from a liquid to a gas, and releases its heat in a condenser as the substance returns from the gaseous state back to a liquid state.


Combination grille and damper assembly covering an air opening or end of an air duct.

Return Air

Air drawn into a heating unit after having been circulated from the heater's output supply to a room.

Scroll Compressor

A specially designed compressor that works in a circular motion versus an up and down piston action.


Seasonal Energy Efficiency Ratio, SEER measures the cooling efficiency in your heat pump or air conditioner. The total cooling of a central unitary air conditioner or unitary heat pump in Btu's during its normal annual usage period for cooling divided by the total electric energy input in watt-hours during the same period. The US government's minimum SEER rating is 10, and the higher the SEER rating, the more efficient the system.

Setback Thermostat

A state-of-the-art electronic thermostat with a built-in memory that can be programmed for different temperature settings at different times of the day.


The temperature to which a thermostat is set to result in a desired heated space temperature.

Split System

Term for a combination air conditioner or heat pump that includes components in two locations, usually one outdoors (condenser coil) and one indoors (evaporator coil).


Device that regulates your heating and air conditioning system so you can adjust the comfort level of your home with a button or a switch; usually located on an inside wall in your house.


A unit of measure for cooling capacity. One ton=12,000 BTUs per hour.


A type of furnace that draws cool air from the bottom and blows the warmed air out the top into the duct work. This type of furnace is usually installed in a basement or closet.


An exhausted fan that captures stale indoor air and vents it outside.


A term for dividing your home into two or more areas or zones, then controlling the comfort level of each separately with programmable thermostats and dampers.