Book an Appointment!


"My air conditioner was installed in a timely manner with no inconvenience whatsoever. Both installers were pleasant and courteous - and left no mess whatsoever. I am impressed and happy with the service."
Merilyn Lewis
What Does That Mean?

What Does That Mean?

A glossary of HVACR terms.


The Air Conditioning Contractors of America, the nationwide association of heating, ventilation, air conditioning, and refrigeration contractors in the United States.


Making sure the system, including air coming into the building, is sufficient to meet heating and cooling needs. The standards for this detailed calculation are included in ACCA’s Manual J®.

British thermal units (BTU’s)

The amount of heat needed to raise the temperature of one pound of water one degree Fahrenheit.


Chlorofluorocarbons, chemical compounds used as refrigerants in air conditioning systems.

Coil Rows of tubing or pipe with fins attached through which a heat-transfer fluid is circulated to deliver heated or cooled air to a building.

Commissioning The final step in installing a heating or air conditioning system, where every component is checked and tested for compliance with codes, ACCA manuals, manufacturer requirements, and occupant needs. At this point the technician will also show the homeowner or building manager how to operate the system.


The outside unit of a heating or air conditioning system. Here the refrigerant condenses from a gas to a liquid and hot or cold air from the building is released to the outside.


A device that removes excess moisture from the air.


The United States Department of Energy, which sets standards for HVACR system efficiency and enforces them. DOE standards include the move to 13 SEER on January 23, 2006.


The tubes, usually metal, that carry heated or cooled air through a building.


Electrical and gas appliances that meet DOE’s highest standards for energy efficiency. ENERGY STAR products include light bulbs, refrigerators, washing machines, and dryers as well as heating and cooling systems.


The United States Environmental Protection Agency, which monitors air, land, and water quality. The EPA makes and enforces rules about hazardous substances and activities. For example, the EPA requires that certain refrigerants used in heating and cooling systems may no longer be manufactured after 2010.


Hydrochlorofluorocarbons, chemical compounds used as refrigerants in heating and cooling systems.

Heat exchanger

The part of a heating or cooling system that transfers heat from one liquid to another. Fans blow air over the heated or cooled liquid, and the air is distributed throughout the building through ducts.

Heat pump

An electrically powered device that extracts available heat from one area and transfers it to another to either heat or cool an interior space.


A device that adds moisture to dry air.


Heating, ventilation, air conditioning; heating, ventilation, air conditioning, and refrigeration.


Indoor air quality.

Latent heat

The humidity of air. Air conditioners remove latent heat as they cool the air.

Load calculation

A mathematical determination of how much cooling and heating an HVAC system must have for occupant safety and comfort. It is based on square footage; building orientation; number, size, and placement of rooms; number and size of windows and doors; amount of insulation; number of floors; climate. Residential load calculations are determined by ACCA Manual J, and commercial load calculations by ACCA Manual N.

Manual D®

An ACCA procedure and ANSI-approved standard covering the design, installation, maintenance, and repair of ductwork.

Manual J®

Developed by ACCA, the ANSI-approved standard residential load calculation method, required by most building codes around the country.

Manual N ®

The industry standard for light commercial building load calculation, developed by ACCA.

Manual RS®

An ACCA manual covering the design, installation, and commissioning of residential HVAC systems.


Hazardous compounds produced by some kinds of mold.


North American Technician Excellence, the nonprofit organization that tests and certifies HVACR technicians.


Planned Maintenance Agreement, providing regular maintenance of residential HVACR systems. Most ACCA member contractors offer PMAs, although they may use different names for them, such as Preventive Maintenance Agreement, Planned Service Agreement, Energy Service Plan, etc.


A refrigerant containing chlorine used in air conditioning systems. The EPA has mandated that R-22 cannot be manufactured after 2010 because it has been linked to the depletion of the ozone layer and global warming. Most commonly referred to by its trademarked name, Freon.


The refrigerant that replaces R-22. It does not contain chlorine and is not hazardous to the environment.


The liquid in heating and air conditioning systems that transfers heat, cooling the air or heating it.

Refrigerant charge (or, “charging the refrigerant”)

The procedure an HVACR technician performs to ensure that the system has enough refrigerant of the right kind to meet heating and cooling needs.

Relative humidity (RH)

The percent of moisture actually in the air compared to the maximum amount of moisture the air can hold at that temperature.

Return side

The part of an HVAC system that takes hot or cool air from the building to be conditioned or vented outside. The return side is “balanced” with the supply side to ensure adequate air flow and comfort.


Seasonal energy efficiency ratio, a measure of the efficiency of central air conditioning systems and air-conditioning heat pumps. The SEER number expresses the amount of cooling delivered (expressed in British thermal units, or BTU’s) for every watt-hour of electricity the system consumes during a cooling season. The higher the SEER number, the more cooling it delivers for the energy it uses and, therefore, the more efficient it is.

Sensible heat

The actual temperature of the air.

Split system

An HVAC system in which the condenser and evaporator are in two different locations. Split systems are generally preferred because they offer more installation options and because smaller tubes penetrate the building envelope.

Supply side

The part of an HVAC system that brings in fresh air to be heated or cooled. The supply side is “balanced” with the return side to ensure adequate air flow and comfort.

Zones, zoned system

Areas of a building that have separate thermostats and other controls. Zoned systems can be set to regulate temperature and humidity in each zone.

© Air Conditioning Contractors of America

Return to the Custom Vac News Release Directory


Contact Us

Custom VAC Ltd.
1567 Logan Avenue
Winnipeg, Manitoba
R3E 1S5
T. 204-775-7744
T. 204-772-5799
F. 204-774-8557


24/7 Emergency Service for Heating and Cooling

Featured Products

Custom Vac - Heating - Cooling - Air Quality Control - Duct Cleaning - Systems Analysis,  Winnipeg, Manitoba. Since 1970. FloodSafe Auto-Shutoff Connectors
Custom Vac - Heating - Cooling - Air Quality Control - Duct Cleaning - Systems Analysis,  Winnipeg, Manitoba. Since 1970. Motorized Air Control Damper
Lennox Furnaces
© 2006/2016 Copyright Custom Vac Ltd.   |   Privacy Policy   |   Sitemap