HVAC Terms & Definitions

AFUE – Annual Fuel Utilization Efficiency. Indicated as a percentage, your furnace’s AFUE tells you how much energy is being

converted to heat. For example, an AFUE tells you how much energy is being converted to heat. For example, an AFUE of 90

means that 90% of the fuel is being used to warm you home, while the other 10% escapes as exhaust with the combustion


AIR HANDLER– Fan blower, filter and housing parts of a system.

ARI– Air Conditioning and Refrigeration Institute – a non-profit, voluntary organization comprised of manufacturers of air

conditioning, refrigeration, and heating products. It publishes standards for testing and rating heat pumps and air conditioners. The information provides the consumer with a standardized unit of comparison between equipment from various manufacturers and ensures a level of quality within the industry.

BLOWER– Fan or air handler devise for moving air.

BTU-British Thermal Unit. Used for both heating and cooling. BTU is a measure of heat given off when fuel is combusted. Or for cooling, it’s a measure of heat extracted from your home. One BTU is equal to the heat given o by a wooden kitchen match.

BTUH-Btu’s per hour

CFC CERTIFICATION-Chlorouorocarbon, a compound consisting of Chlorine, Fluorine, and Carbon. Technicians who repair or service R-12 or R134a refrigerant must be trained and certified by an EPA-approved organization. Training programs must include information on the proper use of equipment, the regulatory requirements, the importance of refrigerant recovery, and the effects of ozone depletion. To be certified, technicians must pass a test demonstrating their knowledge in these areas.

CFM-Cubic Feet per Minute. A measurement of airflow that indicates how many cubic feet of air passes by a stationary point in one minute. The higher the number, the more air is being forced through the system.

CAPACITY-The ability of a heating or cooling system to heat or cool a given amount of space. For heating, this is usually expressed in BTU’s. For cooling, it is usually given in tons.

CARBON MONOXIDE-A colorless, odorless highly poisonous gas produced when carbon-based fuels, such as natural gas, burns without sufficient air nearby.

CHARGE-Amount of refrigeration placed in a refrigerating unit (air conditioner).

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

CONDENSATION-Formed by more heating being absorbed into the air leaving less temperature to carry the water vapor produced in gas combustion to pass out the venting system.

CONDENSER COIL-Part of the outdoor portion of a split system air conditioner or heat pump. By converting refrigerant that is in a gas form back to a liquid, the coil sends heat carried by the refrigerant to the outside.

CONDENSER UNIT-The outside unit, handles the refrigerant providing the cooling (and heating in a heat pump.) It consists of a condensing coil, compressor, fan motor, and control valves.

DAMPER-A device that is located in ductwork to adjust airflow. This movable plate opens and closes to control airflow to certain rooms of your home.

DECIBEL– Decibels (db) are a unit measuring the intensity of noise.

DIRECT VENT-Pulls outside air for combustion and vents combustion gases directly outside.

DOE-Department of Energy is the Federal agency in charge of monitoring the consumption of energy sources.

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

DUAL-FUEL-See Hybrid Heat

DUCTWORK -Hollow pipes used to transfer air from the Air Handler to the air vents throughout your home. Ductwork is one of the most important components of a home heating and cooling system.

ELECTRONIC AIR CLEANER-An electronic device that filters out large particles and contaminants in indoor air. It then electronically pulls out tiny particles and contaminants in indoor air. It then electronically pulls out tiny particles that have been magnetized, such as viruses and bacteria, drawing them to a collector plate.

EVAPORATOR COIL -Part of split system air conditioner or heat pump indoors. The evaporator coil cools and dehumidifies the air by covering liquid refrigerant into gas, which absorbs the heat from the air. The warmed refrigerant is then carried through a tube to the outdoor unit.

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.

FILTER -A device for removing particles from the air.

FLUE-A duct, pipe, or chimney for conveying exhaust gases from a furnace boiler, replace, or water heater to the outdoors.

HVAC-Term used for Heating, Ventilation, and Air Conditioning.

HSPF-The heating Seasonal Performance Factor is a measure of the heating efficiency of a heat pump. The higher the HSPF number, the more efficiently the heat pump heats your home.

HEAT EXCHANGER-The part of a furnace that transfers heat to nearby air.

HEAT PUMP-A product that works just like an air conditioner in cooling mode; however, in heating mode, the refrigerant flow is reversed and heat is extracted from the outside air to heat you home.

HORIZONTAL FLOW-A type of furnace, installed on its “side”, that draws in the air from one side, heats it, and sends the warm air out the other side. Most often used for installations in attics or crawl spaces.

HUMIDIFIER-A piece of equipment that adds water vapor to heated air as it moves out of the furnace. This adds necessary moisture to protect you furnishings and reduce static electricity.

HUMIDISTAT-A control that measures and regulates moisture in the air similar to the way a thermostat measures and regulates heat in the air.

HYBRID HEAT -A Hybrid Heat system is a fuel-savings alternative to traditional heating and cooling systems that combines a furnace with a heat pump, rather than an air conditioner.

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 or door areas, insulation quality, and local climate to determine the heating and cooling capacity needed by your furnace, heat pump, or air conditioner. When referring to heating, this is often known as Heat Loss Analysis, since a home’s heating requirements are determined by the amount of heat lost through the roof, entryways and walls.

MATCHED SYSTEM -A Heating and cooling system comprised of products that have been certified to Perform at promised comfort and efficiency when used together, and used according to design and engineering specifications.

OPERATING COST -The day-to-day cost of running you home comfort equipment, based on energy use.

OUTDOOR UNIT -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.

PLENUM -A sealed chamber, located at the inlet and outlet of an air handler, where conditioned air collects before being distributed or returned through ductwork.

PURON (CARRIER ONLY) -Puron refrigerant is an environmentally sound refrigerant designed not to harm the earth’s ozone layer. Federal law requires that all manufacturers phase out ozone-depleting refrigerants in the next few years. Puron is approved by the US Environmental Protection Agency as a replacement for Freon R22. See Puron vs. R-22. R22 -R22 is a single component HCFC refrigerant with low ozone depletion potential. It has long been used in a variety of air conditioning and refrigerant applications in a variety of markets. Production of R22 will cease in 2015 per the Montreal Protocol.

RECLAIM – Returning used refrigerant to the manufacturer for disposal or reuse.

REFRIGERANT – Substance used in refrigerating mechanism. It absorbs heat by changing from a liquid to a gas, and releases its heat in a condenser as the substance returns from the gaseous state back to liquid state.

REGISTER -Combination grill 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.

SEER -The Seasonal Energy Efficiency Ration is a measure of the cooling efficiency of you air conditioner or heat pump. The higher the SEER number, the more efficient the system is at converting electricity into cooling power.

SCROLL COMPRESSOR-A specially designed compressor that works in a circular motion vs. an up and down piston action.

SPLIT SYSTEM -Refers to an air conditioner or heat pump that has components in two locations. Usually, one part of the system is located inside components in two locations. Usually, one part of the system is location inside (evaporator coil) and the other is located outside (condenser coil).

SUPPLY– The ductwork through which air leaves the source after being conditioned.

THERM-A measurement of 1000,000 BTU’s

THERMIDISTAT -The Thermidistat Control monitors temperatures both inside and outside, as well as indoor humidity and adjusts system operation to maintain the temperature and humidity levels set by the Homeowner.

THERMOSTAT-Unit that monitors and controls you HVAC system products.

TON-A unit of measurement for cooling capacity. On ton = 12,000 BTU’s per hour.

UPFLOW-A type of furnace that draws cool air from the bottom and blows the warmed air out the top into the ductwork. This type of furnace is usually installed in a basement or an out-of-the-way closet.

VENTILATOR-A ventilator captures heating and cooling energy from stale indoor air and transfers it to fresh incoming air.

ZONING-A way to increase you home comfort and energy efficiency by controlling when and where heating and cooling occurs in a home. Programmable thermostats are used to control operating times or the equipment. Dampers are used to direct airflow to certain parts “zones” of the home. There is more to a heating and air conditioning system than its ratings. The quality of the construction and materials used as well as the reliability of the manufacturer and installing contractor can all affect the homeowner’s long-run satisfaction with the purchase. Top-quality, high-efficiency equipment will cost more initially, but it will save you money on utility bills and service calls for years to come.


CONTACT Pensacola Air Repair to find out how we can help you make the right choice.