Lennox: Background for Glossary
Filter Results


Making informed purchasing decisions and getting the best performance from your home comfort system is easier when you know the common terms.


AHRI (Air Conditioning, Heating and Refrigeration Institute)

AHRI is an abbreviation for the Air Conditioning, Heating and Refrigeration Institute, a trade association that develops standards for measuring and certifying product performance. AHRI standards and guidelines are used throughout the world. Equipment with the AHRI Certified® mark has AHRI’s assurance that it will perform accurately and consistently.

Learn More

Air Handler

An air handler, or air handling unit, is the indoor part of an air conditioner or heat pump that moves cooled or heated air throughout the ductwork of your home. It is usually a large metal box containing important elements of an HVAC system that controls airflow and filtration. Lennox® air handlers are among the most efficient and quietest you can buy.

Learn More

Annualized Fuel Utilization Efficiency (AFUE)

A measure of furnace heating efficiency. The higher the AFUE, the more efficient the furnace.

Learn More



Bioaerosols, or biological aerosols, are tiny airborne particles that are biological in nature. High concentrations of bioaerosols in indoor air can lead to respiratory problems and disease. Maintaining proper home humidity levels and installing advanced filtration devices, such as the Healthy Climate PureAir™ air purification system, can help reduce bioaerosols and maintain a healthy environment.

Learn More

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.

Learn More

British Thermal Unit Per Hour (BTUh)

British thermal units per hour.

Learn More


Carbon Monoxide (CO)

Carbon monoxide (sometimes referred to by its chemical abbreviation, CO) is an odorless, colorless, tasteless and poisonous gas that’s produced when fuels such as natural gas burn with insufficient air. When carbon monoxide leaks into your home’s air, it can lead to serious health problems for your family. Regular maintenance of your home’s heating and ventilation system will help ensure it’s not a source of a carbon monoxide leak.

Learn More

Central Air-Conditioning

Central air conditioning (or central A/C) is a system in which air is cooled at a central location and distributed to and from rooms by one or more fans and ductwork. Lennox® central air conditioners are among the quietest and most energy-efficient units you can buy.

Learn More


There are typically two HVAC coils in a system—the condenser coil in the outside air conditioning condenser unit and the evaporator coil in the indoor unit. The coils are what increase or decrease the temperature via heat transfer.

Learn More

Combined Annual Efficiency (CAE)

Combined Annual Efficiency (CAE) is a measure of the amount of heat produced for every dollar of fuel used to heat your home’s air and water. It is used to compare efficiencies of integrated water and space heaters.

Learn More

Composite Fan Blades

Composite Fan Blades are blades which have an exclusive angled design that improves operation and durability, even in the harshest environments. Used in select Lennox® outdoor air conditioners or heat pump units.

Learn More


An AC or heat pump compressor is the part of an outdoor air conditioner or heat pump that compresses and pumps refrigerant to meet household cooling requirements.

Learn More


A condenser (or AC condenser) is the outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the time of the year.

Learn More

Cubic Feet Per Minute (CFM)

Cubic Feet Per Minute (CFM) is a measurement of airflow volume, determined by how many cubic feet of air pass by a stationary point in one minute. Having an accurate estimate of your home’s CFM is key to choosing an HVAC system with the right capacity for your space and needs.

Learn More


Decibel (dB)

A decibel (dB) is a unit used to measure the relative intensity of sound. For example, sound levels in a library are normally about 40 dB, normal conversations range from about 50 to 60 dB, and an operating motorcycle or garbage truck can be as high as 100 dB.

Learn More

Department Of Energy (DOE)

The U.S. Department of Energy (DOE) is a federal agency responsible for monitoring the consumption of energy sources and setting industry efficiency standards for all heating and cooling units manufactured in the U.S.

Learn More

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.

Learn More


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.

Learn More


Ductwork refers to the system of ducts (metal or synthetic tubes) used to transport air from heating, ventilation and air-conditioning (HVAC) equipment throughout your home. Properly installed and well-maintained air ducts are a key component of indoor air quality and home comfort.

Learn More


Electronic Air Cleaner

Electronic air cleaners, sometimes referred to as ionizers or electronic air purifiers, use electrically charged filters to reduce the number of airborne contaminants in your home. As air passes through your heating and cooling system, the cleaner uses electrically charged filters to attract and trap harmful particles to prevent them from recirculating through your home.

Learn More

Energy Efficiency Ratio (EER)

The ratio of cooling capacity to the power input (in watts). The higher the EER rating, the more efficient the air conditioner.

Learn More

Energy Star®

ENERGY STAR® is a program of the U.S. Environmental Protection Agency (EPA) designed to help consumers and businesses save money by choosing energy-efficient products and technologies. Heating, ventilation and air-conditioning (HVAC) equipment with the ENERGY STAR® label meets or exceeds federal guidelines for energy-efficient performance.

Learn More

Environmental Protection Agency (EPA)

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

Learn More

Evaporator Coil

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

Learn More


Fan Coil Unit

A fan coil unit (FCU) is a device that uses a coil and a fan to heat or cool a room without connecting to ductwork. Indoor air moves over the coil, which heats or cools the air before pushing it back out into the room. FCUs can be less expensive to install than ducted systems, and are available in ceiling, floor-mounted and freestanding configurations.

Learn More


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.

Learn More

Gas Furnaces

A gas furnace is the part of an HVAC system that converts natural gas or propane into high-temperate heat for the home.

Learn More

Grid-Tie Inverter Solar System

A grid-tie inverter solar system is the most common and least expensive of all residential solar systems. It 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.

Learn More

GWP (Global Warming Potential)

GWP stands for global warming potential. It refers to a formula used to measure how much a substance contributes to global warming over a period of time. Specifically, it represents how much heat a substance traps when compared to CO2.

Learn More


Heat Exchanger

A heat exchanger is a heating component that is located in the furnace and transfers heat to the surrounding air, which is then pumped throughout the home.

Learn More

Heat Pump

A heat pump is an HVAC unit that heats and cools by extracting and transferring heat. Unlike traditional air-conditioners, heat pump systems have the ability to both cool a home during the summer months and heat it during winter. They do this through a reversible refrigerant cycle within the system. During cold weather, a heat pump extracts from outdoor air and transfers it inside to warm the home. This same process is reversed during warm weather for cooling, with the heat pump extracting heat from inside and transferring it outside.

Learn More

Heating Seasonal Performance Factor (HSPF)

The heating efficiency rating for heat pumps. The higher the rating, the more efficient the heat pump.

Learn More

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.

Learn More


A humidifier is a device that adds moisture to indoor air in a single room or throughout an entire house. Whole-home humidifiers may use the fan in your furnace or air handler to blow humidified air throughout the ductwork, or they may work independently of your heating and cooling system to maintain humidity levels even when the furnace or air handler isn’t operating.

Learn More


A humidistat (sometimes called a humidistat control) is a device that works with a home’s heating and cooling system to automatically adjust the amount of moisture in the air to maintain a specific humidity level throughout the home.

Learn More


HVAC stands for Heating, Ventilation, and Air Conditioning and is used to describe a complete home comfort system used to heat and cool a home.

Learn More

HVAC Damper

An HVAC damper (also called a duct damper) is a movable plate, located in the ductwork, that regulates airflow and redirects it to specific areas of the home. Dampers are typically used in zoning or “zone control” systems.

Learn More

HVAC Zoning System

An HVAC zoning system (also referred to as “zoned HVAC”) is a heating and cooling system that uses dampers in the ductwork to regulate and redirect air to specific areas of the home. This allows for the creation of customized temperature zones throughout the home for increased comfort and efficiency.

Learn More



An iComfort®–enabled product is one that is designed to work with an iComfort® programmable thermostat as part of an advanced home comfort system. When you choose a heating, cooling or humidity control product that’s iComfort-enabled, you’re ensuring a higher level of home comfort and control.

Learn More

Indoor Coil

See Evaporator Coil.

Learn More

ISO 9000

A family of international standards for quality management and assurance.

Learn More


Matched Systems

Simply put, matched systems are complete HVAC systems consisting of individually efficient products that realize even greater efficiency when paired together.

Learn More

MERV Rating

The Minimum Efficiency Reporting Value (MERV) rating is used to rank the efficiency of air filters. Every air filter has holes that allow air and particles to pass through. The smaller the holes, the fewer particles that can pass through. Higher MERV ratings indicate smaller holes, and therefore a more efficient filter.

Learn More


A unit of measure equal to one millionth of a meter, or 1/25,000 of an inch. Airborne particles – such as dust, dander, mold and viruses – are measured in microns. These tiny particles can circulate in your home’s air and have harmful effects on your family’s health and comfort.

Learn More


Everything you need to know about Mini-Split ductless heat pumps and air conditioners.

Learn More


NATE Certification

North American Technician Excellence (NATE) conducts rigorous, independent testing verifying the real-world knowledge and application of HVAC technicians and installers.

Learn More

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. 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.

Learn More


Off-Grid Or Off-The-Grid

An off-grid or off-the-grid system is an electricity-generating system that operates independently from the utility grid, providing all of the electricity needed in the home, and is generally more expensive than grid-tied system ideal for homes located in remote areas without utility service, or where installing power lines would be extremely costly.

Learn More

Oil Furnace

An oil furnace is the part of an HVAC system that converts heating oil (similar to diesel) into high-temperate heat for the home.

Learn More

Outdoor Coil

See Condenser.

Learn More


Packaged Units

Heating and cooling systems contained in one outdoor unit.

Learn More


Particles are tiny substances measuring less than 100 microns in diameter. Indoor air can be filled with particles, some of which can be seen with the naked eye, such as dust and dirt. Others can only be seen with a microscope, such as bacteria and viruses, which typically measure only one micron or smaller in diameter. All of these airborne particles can have significant impacts on your family’s health and comfort.

Learn More

Programmable Thermostat

A programmable thermostat is a thermostat with the ability to adjust home heating and cooling equipment according to a pre-set schedule. For instance, a programmable thermostat could be set to maintain a home temperature of 72 degrees throughout the day, and 65 degrees from 11:00 p.m. to 7:00 a.m. every night.

Learn More


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.

Learn More

R-410A Refrigerant

R-410A, is a chlorine-free, hydrofluorocarbon (HFC) refrigerant originally developed as a more environmentally friendly replacement for R-22. R-410A was developed and patented in 1991 by Honeywell.

Learn More


Refrigerant is the working fluid used in air conditioners, refrigeration, and heat pump systems. It is a chemical compound that changes temperature as it transitions between liquid and gas form – cooling as it vaporizes, and heating up as it condenses. It is this property that facilitated a system’s ability to heat and cool.

Learn More

Refrigerant Lines

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

Learn More


Scroll Compressor

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

Learn More


Simply put, this rating measures how much energy a heating and cooling system uses to operate. Learn how you can use SEER and SEER2 ratings to increase efficiency – and savings – in your home.

Learn More

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 conditioners or heat pump units.

Learn More

Split System HVAC

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

Learn More



A thermidistat is a device that monitors indoor temperature, humidity levels and automatically adjusts your heating or cooling system to maintain desired levels.

Learn More


A thermostat is a device that monitors the indoor temperature and automatically adjusts your heating or cooling system to maintain the desired level.

Learn More


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

Learn More

Two-Stage Operation

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

Learn More


Upflow Furnace

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 basements, closets and attic installations.

Learn More


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.

Learn More


A ventilator is a device that replaces the stale, recirculated air inside your home with fresh, filtered outdoor air. An energy recovery ventilator (ERV) is ideal for warm and humid climates, since it cools and dehumidifies the incoming outdoor air. A heat recovery ventilator (HRV) is more appropriate for colder climates, as it transfers heat from recirculated air to the fresh incoming air.

Learn More
Map pin

Get answers from a Lennox® Dealer.

It's easy to find an expert Lennox Dealer who can help you make the most of your HVAC system.

View Now

Get the answers you need from your preferred dealer:

AZ Air Cond & Heating

Go to my Dealer's Page
Rio Verde
Tom's Thumb Trailhead
McDowell Mountain Regional Park
Mountain Gate
Eagle Mountain
Butterfly Wonderland
Roadrunner Park
Grayhawk Golf Club
Fountain Hills
Hurricane Harbor Park
Fort McDowell
Phon D Sutton
Arizona Business Park
Thunder Bird Conservation Park
Taliesin West
Phoenix Mountains Preserve
Paradise Valley
alt goes here
alt goes here

Map data ©2022 Google
alt text goes here

It's also easy to find an expert Lennox® dealer who can help
you make the most of your HVAC system.

View Now