Common HVAC Terms for Homeowners

The HVAC industry uses a wide range of technical terms that many homeowners may not be familiar with. Without an understanding of key terms like AFUE and SEER, it is harder to make an educated, informed purchase. To help you gain insight into the industry and make informed decisions regarding your HVAC system, here is a list of common terms and definitions:

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Common HVAC Terms: A Homeowner's Guide

A

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.

Annualized Fuel Utilization Efficiency (AFUE)

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

B

Boiler

A residential boiler is a home heating appliance that uses natural gas, propane or oil as its primary fuel source to heat water, which is then circulated through a home’s piping system to provide warmth. It is commonly found in homes with radiators, baseboard heaters, or in-floor radiant heating systems.

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.

C

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 through ductwork. 

Charge

The amount of refrigerant in a system.

Coil

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.

Compressor

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.

Condenser

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.

D

Damper

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.

Ductwork

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.

E

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.

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.

F

Fresh Air Intake

An opening through which outdoor air is drawn into a system.

H

Heat Exchanger

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

Heat Pump

A heat pump is a 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.

M

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.

R

Refrigerant

A chemical that produces a cooling effect while expanding or vaporizing. Most residential air-conditioning units contain the standard R-22, R410A or R454B refrigerant, or freon.

Refrigerant Lines

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

S

Seasonal Energy Efficiency Ratio (SEER)

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

T

Ton

Unit of measurement for determining cooling capacity. One ton equals 12,000 BTU per hour.

.

Two-Stage Operation

When an HVAC system provides two levels of heating or cooling output for enhanced temperature control, energy efficiency and indoorair quality.

V

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.

Z

Zoning

A 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.