Annualized Fuel Utilization Efficiency is the fuel efficiency rating for warm-air, gas or oil-fired furnaces less than 150,000 Btuh. The higher the AFUE, the more efficient the furnace.

Air Handler
The indoor part of an air conditioner or heat pump that moves cooled or heated air throughout the ductwork of your home. An air handler is usually a furnace or a blower coil.

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) is the trade association representing manufacturers of air conditioning, heating, and commercial refrigeration equipment. An internationally recognized advocate for the industry, AHRI develops standards for and certifies the performance of many of these products.

A British thermal unit is a unit of heat energy. One Btu is the amount of heat required to raise one pound of water by one degree Fahrenheit. The higher the Btu rating, the greater the heating capacity of the system.

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, in tons.

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

Central Air Conditioning System
System in which air is treated at a central location and distributed to and from rooms by one or more fans and a series of ducts.

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

Condenser Coil
The outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the time of the year.

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.

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

A square channel or round tube by which air is distributed from the air handler (e.g.,rooftop unit, furnace, fan coil or VAV box) to the room.

A label attached to HVAC systems that meet or exceed the EPA guidelines for energy efficiency. Applies to products 20 tons and less.

The Environmental Protection Agency develops and enforces federal environmental regulations for the United States. The EPA oversees the nationwide ENERGY STAR® program.

Evaporator Coil
The part of the air conditioner or heat pump that is located inside the air handler. Its primary function is to absorb the heat from the air.

Fan Coil
A unit that includes a cooling and/or heating coil and a fan to move air through the ductwork to a room. Air filters and accessories to introduce outside ventilation air may also be included.

Heat Exchanger
Transfers heat from one fluid to another without the fluids coming into direct contact with one another.

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 the air ducts. In the summer, it reverses the process and removes heat from the space and releases it outdoors.

An indoor air quality device that introduces moisture to heated air as it passes from the furnace into the ductwork for distribution throughout the building.

Stands for heating, ventilation and air conditioning.

MERV Rating
The Minimum Efficiency Reporting Value 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 and the greater the efficiency.

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

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

A chemical that produces a cooling effect while expanding or vaporizing.

Refrigerant Lines
Two copper lines that connect the outdoor air conditioner or heat pump to the indoor evaporator coil.

The Seasonal Energy Efficiency Ratio is an energy efficiency rating for air conditioners. The higher the SEER, the better the energy performance and savings. The Department of Energy’s established minimum SEER rating for cooling is 10.00. This rating applies only to equipment 5 tons and under.

Single Package
A heating and cooling system contained in one outdoor unit.

Split System
A combination heat pump or air conditioner with indoor components, such as a furnace or blower coil. Split systems should be matched for optimal efficiency.

Usually found on an inside wall, this device controls heating and cooling equipment, allowing simple adjustments of temperature and other comfort control factors, such as humidity and airflow.

Unit of measurement for determining cooling capacity. One ton equals 12,000 Btuh.

Two-Stage Operation
When a unit provides two levels of heat output for greater temperature control.

Variable-Speed Motor
A variable speed motor provides a quiet, consistent flow of air for enhanced comfort, efficiency and humidity control. According to the Office of Energy Efficiency & Renewable Energy, a variable-speed motor running continuously at a half speed may use up to 75% less power that a single-stage motor uses to move the same amount of air.

A system that exchanges stale, recirculated indoor air with fresh, filtered outside air.

A way to increase comfort and energy efficiency by controlling when and where heating and cooling occurs. Programmable thermostats are used to control operating times of the equipment. Dampers are used to direct air flow to specified zones of a building.