Understanding HVAC Terms

Though your definitions of "comfort" may be different than your neighbor's, knowing these terms can help make your search for improved comfort and efficiency much less confusing and much more effective.

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

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

BTU -British Thermal Unit. Used for both heating and cooling, BTU is a measure of the 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 off by a wooden kitchen match.

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 BTUs. For cooling, it is usually given in tons.

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 in heat to warm your home or getting rid of heat to keep your home cool.

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.

Damper -A type of "valve" used in duct work that opens or closes to control airflow. Used in zoning to control the amount of warm or cool air entering certain areas of your home.

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

Electronic Air Cleaner (EAC) -An electronic device that filters out large 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.

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 a Heat Loss Analysis, since a home's heating requirements are determined by the amount of heat lost through the roof, entry ways and walls.

Evaporator Coil -Part of a split-system air conditioner or heat pump located indoors. The evaporator coil cools and dehumidifies the air by converting liquid refrigerant into a gas, which absorbs the heat from the air. The warmed 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.

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.

Horizontal Flow -A type of furnace, installed on its "side," that draws in 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 your furnishings and reduce static electricity.

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 day-to-day cost of running your home comfort equipment, based on energy use.

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.

PuronT Refrigerant -Puron is an environmentally sound refrigerant designed to protect the earth's ozone layer. Federal law requires all manufacturers phase out ozone depleting refrigerants in the next few years. Puron is approved by the US Environmental Protection Agency as a replacement from Freon 22*.

Reclaiming -Returning used refrigerant to the manufacturer for disposal or reuse.

Reciprocating Compressor -A type of compressor used in air conditioners that compresses refrigerant by using a type of "piston" action.

Recycling -Removing, cleaning and reusing refrigerant.

SEER -The Seasonal Energy Efficiency Ratio is a measure of the cooling efficiency of your 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.

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.

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 (evaporator coil) and the other is located outside your home (condenser coil).

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 your HVAC system products.

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

Upflow -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 an out-of-the-way closet.

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

Zoning -A way to increase your 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 of the equipment. Dampers are used to direct air flow to certain parts or "zones" of the home.

* Freon is a trademark of E.I. Dupont.