Commonly Used Terms

Making the right decision when it comes to purchasing a heating or cooling appliance is hard enough without having to decipher terms like "Advanced Reciprocating Compressor" or "Load Analysis."

Our simple guide to heating and cooling terms can help you feel like a pro when you choose your next appliance.

AFUE or 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 90 percent of the fuel is being used to warm your home, while the other 10 percent escapes as exhaust with the combustion gases.

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

Air Handler--The portion of your air conditioner or heating system that forces air through your home's ductwork.

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

BTUH or British Thermal Unit per Hour--The unit of heat required to raise one pound of water by one degree Fahrenheit.

CFM or Cubic Feet per Minute--A measurement of airflow that indicates how many cubic feet of air pass 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 BTUs. 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, burn without sufficient air nearby.

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 with a heat pump 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 in ductwork 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.

DB or Decibels--A unit measuring the intensity of noise.

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

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.

EAC or Electronic Air Cleaner--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.

EER or Energy Efficiency Ratings--Measure the efficiency with which a product uses energy to function. It is calculated by dividing a product's BTU output by its wattage.

Energy Saver Switch--An energy saver switch causes the air conditioner's fan and compressor to cycle on and off together, reducing energy use.

Energy Star--Energy Star is a government-backed program helping businesses and individuals protect the environment through superior energy efficiency. Products with the Energy Star rating are efficient and save costs on energy bills.

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 (or vice versa). A blower motor, typically in a furnace, then moves air over the coil to either heat or cool your home.

Fan Coil--An indoor component of an air conditioner or heat pump system, used in place of a furnace and evaporator coil, to change the refrigerant from a gas to a liquid (or vice-versa) and blow air over the coil to cool or heat your home.

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

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 your home.

Horizontal Flow--A type of furnace, installed on its side, which 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 furniture and reduces static electricity.

Load Analysis--A series of studies performed to determine the heating or cooling requirements of your home. An energy load analysis uses information such as 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, the load analysis 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.

Low Boy--A type of furnace that is lower in height than traditional furnaces and occupies more floor space.

MERV or The Minimum Efficiency Reporting Value--The standard comparison of the efficiency of an air filter. The MERV scale ranges from 1 (least efficient) to 16 (most efficient) and measures a filter's ability to remove particles from 3 to 10 microns in size.

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 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.

Two-Stage--The two-stage gas furnaces use a two-stage gas valve and patented control algorithm allowing them to more closely meet the heating needs of the home. The end result is even, consistent heating.

R410A Refrigerant--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. R410A Refrigerant is approved by the U.S. Environmental Protection Agency as a replacement for Freon R-22.

R-22--R-22 is a single component HCFC refrigerant with low ozone depletion potential. It has long been used in a variety of markets. Production of R-22 will cease in 2015 per the Montreal Protocol.

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

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

Recycling--Removing, cleaning and re-using refrigerant.

Refrigerant Lines--Two copper lines that connect the Condenser (Outdoor) Coil to the Evaporator (Indoor) Coil.

SEER or The Seasonal Energy Efficiency Ratio--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 versus 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.

Single Package Product--One outdoor unit that contains both a heating and cooling system.

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).

Thermostat--Unit that monitors and controls your HVAC system products.

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

Total Home Comfort System--The ultimate solution to providing you with consistent, customized home comfort, despite the ever-changing weather.

Two-Stage Compressor--Two-stage compressors are capable of two levels of operation: a low stage and a high stage. Properly sized equipment will operate 80 percent of the time in low stage, enhancing efficiency and comfort with lower humidity levels and quieter operation. It's like getting two air conditioners or heat pumps
in one system.

TXV or Thermostatic Expansion Valve--A precision device used to meter the flow of liquid refrigerant entering at a rate that matches the amount of refrigerant being boiled off in the evaporator.

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 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.