ACCA: Air Conditioning Contractors of America.
AFUE: Annual Fuel Utilization Efficiency. A measure of a gas furnace’s efficiency in converting fuel to energy. The higher the rating, the more efficient the unit. The unit is more efficient when the rating is higher.
AGA: Abbreviation for American Gas Association, Inc.
Air Cleaner: A piece of machinery that removes unwanted particles from moving air.
Air flow Volume: The amount of air the system circulates through your home, indicated in cubic feet per minute (cfm). Correct airflow depends on the indoor unit, the ductwork, the outdoor unit, and even whether the filters are clean.
Air handler: The portion of the central air conditioning or heat pump system that moves cooled or heated air throughout a home’s ductwork. In some systems a furnace will handle this function.
ARI: Air Conditioning & Refrigeration Institute.
ASHRAE: American Society of Heating, Refrigeration and Air Conditioning Engineer
Capacity: The ability of a heating or cooling system to cool or heat a given amount of space. For heating, this is usually expressed in BTU’s. For cooling, it is often given in tons.
CFM : The abbreviation for cubic feet per minute, commonly used to measure the rate of air flow in an air conditioning system.
Charge: Adding refrigerant to a system. Refrigerant is contained in a sealed system or in the sensing bulb to a thermostatic expansion valve.
Condenser Fan: The fan that distributes air over the aircooled condenser.
Contactor: A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the contacts to be pulled in or closed.
Defrost: The process of removing ice or frost buildup from the outdoor coil during the heating season.
Degreeday: A computation that measures the amount of heating or cooling needed for a building. A degreeday is equal to 65 degrees Fahrenheit minus the mean outdoor temperature.
Dehumidifier: An air cooler that removes moisture from the air. This unit reduces water vapor in air by cooling the air below the dew point; removing water vapor from the air by chemical means, refrigeration, etc.
Diffuser: A grille over an air supply duct having vanes to distribute the discharging air in a defined pattern or direction.
DOE: Department of Energy
Downflow Furnace: A furnace that pulls in return air from the top and discharges warm air at the bottom.
Drain Pan: Also referred to as a condensate pan. This is a pan used to catch and collect condensate (in residential systems vapor is liquefied on the indoor coil, collected in the drain pan and removed through a drain line).
Dry Bulb Temperature: Heat intensity, measured by a dry bulb thermometer.
Dry Bulb Thermometer: An device that measures air temperature independently of humidity.
Ductwork: A pipe or conduit through which air is supplied. Ducts are typically made of metal, fiberboard or a flexible material. In a home comfort system, the size and application of ductwork is critical to performance and is as principal as the equipment.
DX: Direct expansion. A system in which heat is passed on by the direct expansion of refrigerant.
EPA: Environmental Protection Agency. ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping us all save money and protect the environment through energy efficient products and practices.
Evaporator Coil (or Indoor Coil): The other half of an air conditioning system, this network of tubes filled with refrigerant which is located inside the home within the indoor unit, take heat and moisture out of indoor air as liquid refrigerant evaporates.
Expansion Valve: A refrigerant-metering valve with a pressure or temperature controlled orifice.
Flue: Any vent or duct, pipe, or chimney for carrying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors.
Furnace: That part of an environmental system which converts gas, oil, electricity or other fuel into heat for distribution within a structure.
Fuse: A fuse is a type of overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows, which breaks the circuit in which it is connected, thus protecting the circuit’s other components from damage due to excessive current.
Gas Furnace Heat Exchanger: Found in the furnace, the heat exchanger transfers heat to the surrounding air, which is then transported throughout your home.
Heat Loss: The rate of heat transfer from a building interior to the outdoors.
Heat Pump: An automated compression cycle refrigeration system that can be switched to either heat or cool the controlled space.
Heat Transfer: The movement of heat energy from one area to another. The means for such movement are convection , conduction, and radiation. Heat will flow naturally from a warmer to a cooler space or material.
Heating Coil: Any coil that serves as a heat source.
Hertz: A measure of the number of cycles or wavelengths of electrical energy per second; U.S. electricity supply has a standard frequency of 60 hertz.
Media: The material in a filter that traps and holds the impurities. These HVAC filter media include fiberglass filter media, polyester filter media, dog hair filter media, blue/green filter media, charcoal filter media, and others.
OEM: Original equipment manufacturer.
Refrigerant: A chemical substance that produces a refrigerating effect while expanding and vaporizing.
Sensible Heat: That heat which, when added to or taken away from a substance, causes a change in temperature.
Setpoint: The temperature or pressure at which a controller is set for desired comfort level.
