HVAC Glossary

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z


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

Air-Conditioning And Refrigeration Institute (ARI)
An industry trade association that develops standards for measuring and certifying product performance. For instance, ARI Standard 270 provides guidelines for establishing sound levels for outdoor air-conditioning equipment.

Annualized Fuel Utilization Efficiency (AFUE)
A measure of furnace heating efficiency. The higher the AFUE, the more efficient the furnace. The minimum standard percentage is 78%.


Microscopic living organisms suspended in the air that grow and multiply in warm, humid places.

British Thermal Unit (BTU)
A measurement 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.

British Thermal Unit Per Hour (BTUh)
British thermal units per hour.


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

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

Combined Annual Efficiency (CAE)
A measure of the amount of heat produced for every dollar of fuel consumed for both home and water heating.

Communication Module
A component of a SunSource® Home Energy System that shows system status and environmental benefits in real time.

Composite Fan Blades
Blades that are manufactured with rugged materials and an exclusive angled design that improve operation and durability, even in the harshest environments. Used in select Lennox® outdoor air conditioner or heat pump units.

The part of an outdoor air conditioner or heat pump that compresses and pumps refrigerant to meet household 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.

Cubic Feet Per Minute (CFM)
A measurement of how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air is being moved through the duct work by the system.


A movable plate, located in the duct work, that regulates airflow and directs it to areas that need it most. Typically used in a zoning application.

Decibel (dB)
A unit used to measure the relative intensity of sound.

Department Of Energy (DOE)
A federal agency responsible for setting industry efficiency standards and monitoring the consumption of energy sources.

Dry-Charged Unit
An air-conditioner or heat pump that is shipped dry and charged with refrigerant at the place of installation. Dry-charged units are appropriate for homeowners who need a replacement unit compatible with R-22 refrigerant.

Dual Fuel
A comfort system that pairs an electric heat pump with a gas furnace and alternates between the two fuel sources to maximize comfort and efficiency.

The method by which air is channeled from the furnace or the blower coil throughout your home.


Electronic Air Cleaner
An electronic device that filters out large particles and bio-aerosols in indoor air.

Energy Star®
A designation of the U.S. Environmental Protection Agency (EPA). Attached to HVAC products that meet or exceed federal guidelines for energy-efficient performance.

Environmental Protection Agency (EPA)
An agency of the U.S. government that develops and enforces federal environmental regulations and oversees the nationwide ENERGY STAR® program.

Evaporator Coil
The part of an air conditioner or heat pump that absorb the heat from the air in your house. It is located inside the air handler or attached to the furnace.


Filter Performance Rating – It utilizes a color and number scale from 7 to 15 that closely resembles MERV rating.


Garage Heaters
Natural or propane gas units that provide warmth for car garages of almost any size during the winter months. Separated combustion models provide heating for hard-to-heat applications.

Grid-Tied System
The most common and least expensive of all residential solar systems. Allows homeowners to use their own solar-generated electricity to save energy and reduce costs. The utility company’s grid, or network of power stations, serves as the backup power source.


Heat Exchanger
A heating component that’s located in the furnace and transfers heat to the surrounding air, which is then pumped throughout the home.

Heat Pump
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 a home’s air ducts. In the summer, it reverses the process and removes heat from the house and releases it outdoors.

Heating Seasonal Performance Factor (HSPF)
The heating efficiency rating for heat pumps. The higher the rating, the more efficient the heat pump.

Horizontal Flow
Describes an air handler or furnace that is positioned on its side and circulates air in one end and out the other. Ideal for attic or crawl space installations.

An indoor air quality product that adds moisture to heated air as it passes from the furnace into the duct work for distribution throughout the home.

An automatic device used to maintain humidity at a fixed or adjustable set point.

Heating, Ventilation and Air Conditioning.


Refers to products from the Dave Lennox Signature® Collection of heating, cooling and humidity control products that are configured to work with an iComfort® programmable thermostat as an advanced home comfort system.

Indoor Coil
See Evaporator Coil.

Interconnection Agreement
See Net Metering.

ISO 9000
A family of international standards for quality management and assurance.


MERV Rating
Minimum Efficiency Reporting Value, 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 higher the efficiency.

A unit of measure equal to one millionth of a meter, or one thousandth of a millimeter.

Micro-particle Performance Rating (MPR) system to demonstrate a filter’s ability to capture the smallest airborne particles—from 0.3 to 1 micron in size from the air passing through the filter.


Net Metering
A service available from many utility providers in which homeowners get full retail value for most, if not all, of the electricity produced by their own generating system, such as a SunSource® Home Energy System. A utility meter keeps track of the “net” difference between the electricity used from the utility provider and the electricity produced by the homeowner’s system.


Off-Grid Or Off-The-Grid
An electricity-generating system that operates independently from the utility grid, providing all of the electricity needed in the home, and are generally more expensive than grid-tied systems. Ideal for homes located in remote areas without utility service, or where installing power lines would be extremely costly.

Outdoor Coil
See Condenser Coil.


Packaged Unit
A heating and cooling system contained in one outdoor unit.

Any substances measuring less than 100 microns in diameter. The U.S. EPA has found that particles less than 2.5 microns are responsible for the health effects of greatest concern.

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


R-22 Refrigerant
The old standard for residential air conditioners, now being phased out by the U.S. EPA. Lennox offers dry-charged units for those who still have R-22 compatible systems.

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

A chemical that produces a cooling effect while expanding or vaporizing. Most residential air conditioning units contain the standard R-22 refrigerant, or Freon.

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


Scroll Compressor
A specially designed compressor that works in a circular motion, as opposed to up-and-down piston action.

Seasonal Energy Efficiency Ratio (SEER)
Seasonal Energy Efficiency Ratio, an energy efficiency rating for air conditioners. The higher the SEER, the more efficient the unit.

SilentComfort™ Outdoor Fan Motor
Describes a motor with electronic sensor technology that helps optimize overall system performance while keeping sound levels low. Used in select Lennox outdoor air conditioner or heat pump units.

Solar Module
A component of a SunSource® Home Energy System that mounts on a home’s roof to capture the energy of the sun and use it to heat and cool the home.

Describes select air conditioners and heat pumps from the Dave Lennox Signature® Collection that are designed to work with solar modules in a SunSource® Home Energy System.

Split System
A heating and cooling system that includes an indoor unit, outdoor unit and a thermostat.


A unit that monitors temperature and humidity and adjusts heating or cooling system to maintain desired levels.

A unit that allows homeowners to monitor and adjust heating and cooling equipment.

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

Two-Stage Operation
Provides two levels of heating or cooling output for enhanced temperature control, energy efficiency and indoor air quality.


Describes an air handler or furnace that is installed in an upright position and circulates air through the side or bottom and out through the top. Typically used in basement, closet and attic installations.


Variable Speed Motor
A motor that operates at a wide range of speeds to precisely control the distribution of heated and cooled air throughout the home.

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


Zoning System
A heating and cooling system that creates customized temperature zones throughout the home for increased comfort and efficiency.

© 2024 Nordic Pure /Designed by:LaunchUX