HVAC Glossary

Serving South Carolina From Two Convenient Locations

Columbia
1125 Sparkleberry Ln. Ext
Columbia, SC 29223
803.788.8081

Bluffton
591-K2 Browns Cove Rd.
Ridgeland, SC 29936
843.757.6247

AFUE
Annualized Fuel Utilization Efficiency is a measure of your furnace’s heating efficiency. The higher the AFUE percentage, the more efficient the furnace. The minimum percentage established by the DOE for furnaces is 78%.

AHRI
Air-Conditioning, Heating, and Refrigeration Institute

Air Circulation
The natural or forced movement of air within a conditioned space.

Air Conditioner
A system of machinery and devices that control the temperature, moisture, and cleanliness of the air that flows through the equipment.

Air Handler
An equipment cabinet that contains a blower (and other devices, such as coils and filters) that moves air throughout the air distribution system.

Air Leakage
The uncontrolled exchange of air between the interior of a dwelling and the outdoors through unintended openings in the building envelope and /or unintended openings in ducts that run through unconditioned spaces.

Blower
A ducted fan used to distribute air to a dwelling.

Blown Insulation
Loose insulation commonly used in hard to reach places that might be difficult to insulate with batts or rigid board. Typically, installed in attics and walls by a blowing machine.

British Thermal Unit (BTU)
The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit (Equivalent to the amount of heat produced by burning one wooden match). (12,000 BTUs = 1 Ton)

Burner
A device that introduces fuel, with or without air or oxygen to a combustion chamber for combustion.

Carbon Monoxide
An odorless, colorless, tasteless, poisonous and flammable gas that is produced when carbon burns with insufficient air.

Central System
Heating and cooling for a collection of rooms is provided by one piece of equipment that uses duct or pipes to condition the rooms.

Central System (Single Zone)
One thermostat controls the output of the primary equipment (with no regards to the conditions in remote rooms and spaces).

Central System (Multi Zone)
A collection of room thermostats controls the output (CFMs) of the supply air outlets according to the conditions in the various rooms and spaces. A master control panel monitors the action of the local thermostats and operates the function of the primary equipment accordingly.

Cubic Feet per Minute (CFM)
Cubic Feet per Minute of air flow: Flow rate for ducted flow; or the flow through primary heating and cooling equipment, supply outlets, returns, and so forth.

Compressor
The part of the outdoor air conditioner or heat pump that compresses and pumps refrigerant to meet household cooling requirements.

Condenser
A heat transfer device used to convert vaporized refrigerant into liquid refrigerant.

Condensing Unit
A package of refrigeration equipment consisting of a compressor, condenser, controls, and associated hardware.

Damper
A movable plate, located in the ductwork that regulates airflow. Dampers are used to direct air to the areas that need it most. Typically used in a zoning application.

dB
A decibel is a unit used to measure the relative intensity of sound.

Dehumidification
The use of mechanical cooling equipment or chemical-process equipment to extract water vapor from air.

Dual Fuel
A comfort system that pairs an electric heat pump with a gas furnace, providing an energy-efficient alternative to the conventional furnace/air conditioner combination.

Duct System
A network of tubular or rectangular pipes and connectors (elbows, tees, branch fittings, and boot fittings) used to move air from one point to another.

EER
Energy Efficiency Ratio.

Evaporator
The refrigeration system heat exchanger used to evaporate liquid refrigerant.

Fan
A motor driven device that has rotating blades that move air.

Flue
A duct used to move gases from the combustion chamber to the atmosphere.

Germicidal UV Lamp
A lamp installed on a forced air system to disinfect air, removing harmful micro-organisms out of the air flow and from forming around the drain pan and coil.

Grille
A supple or return air fixture that has a frame and a perforated covering.

Heat Exchanger
A device in which heat is transferred from one fluid to another, such as a condenser or evaporator.

Heat Pump
A heat pump is an HVAC unit that heats or cools by moving heat. During the winter, a heat pump draws heat from outdoor air and circulates it through your home’s air ducts. In the summer, it reverses the process and removes heat from your house and releases it outdoors.

Humidifier
A device that adds moisture to air being introduced into the occupied space by a duct system or a device that directly adds moisture to the space.

HVAC
Heating, Ventilation, and Air Conditioning.

Infiltration
Uncontrolled outdoor air leakage into a conditioned space through cracks and openings in the exposed surfaces; leakage through an attic ceiling; and leakage through the interior partitions that are air-coupled to an attic, a leaky crawlspace or a leaky basement.

Mastic
A flexible adhesive for joining building materials (ductwork).

MERV (Minimum Efficiency Reporting Value)
The rating of a filter describes the size of the holes in the filter that allow air to pass through. The higher the MERV rating, the smaller the holes in the filter, the higher the efficiency.

Programmable Thermostat
A thermostat with the ability to record different temperature/time settings for your heating and/or cooling equipment.

R-410A Refrigerant
A chlorine-free refrigerant that meets the EPA’s newest, most stringent environmental guidelines.

Refrigerant
A chemical that produces a cooling effect while expanding or vaporizing. Most residential air conditioning units contain the standard R-22 refrigerant, or Freon.

Register
A supply air grille equipped with a damper.

Return Air
Air removed from a conditioned space to be processed by the heating and cooling equipment.

SEER
The Seasonal Energy Efficiency Ratio is an energy efficiency rating for air conditioners. The higher the SEER, the better the energy performance, the more you save. The DOE’s established minimum SEER rating for cooling is 13.00.

Sensible Heat
The heat (loss or gain) associated with the temperature change of a substance that does not experience a change of phase during the heat transfer process.

Supply Air
Air delivered to the conditioned space by heating and cooling equipment.

Thermostat
An instrument that senses a change in the temperature at a point and uses this information to control the operation of a mechanical device.

Variable Speed Motor
A motor that automatically adjusts the flow of warm or cool air for ultimate comfort.

Zone
A room or collection of rooms under control of one thermostat.