HVAC Glossary of Terms

Terms and definitions for heating, cooling and indoor air quality products.

AFUE: Annualized Fuel Utilization Efficiency is a measurement of your furnace’s heating efficiency.

Airflow: The movement or distribution of air.

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

Air Handler/Coil Blower: An 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.

Bioaerosols: Microscopic living organisms suspended in the air that grow and multiply in warm places.

Btu: 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 of a system, the greater the heating capacity.

CAE: The combined annual efficiency is a measure of the amount of heat produced for every dollar of fuel consumed for both home and water heating.

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

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

CFM: Stands for Cubic Feet per minute. This measurement indicates how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air moved through the ductwork system.

Compressor: The part of the 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.

Damper: A movable plate that is located in the ductwork, helping regulate airflow. Dampers are used to direct air to the areas that need it most.

dB:  A measurement of sound, a decibel is used to measure the relative intensity of sound.

DOE: The Department Of Energy is 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

Dual Fuel:  A comfort system that pairs an electric heat pump with a gas furnace, providing an energy-efficient alternative to the conventional furnace/air conditioner combination.

Ductwork: The method by which air is channeled from the furnace throughout your home.

Electronic Air Cleaner:  An electronic device that filters out large particles and bioaerosols in indoor air.

Energy Star: An EOA designation attached to HVAC products that meet or exceed EPA guidelines for high-efficiency.

EPA: The Environmental Protection Agency  develops and enforces federal environmental regulations. 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 or attached to the furnace. its primary function is to absorb the heat from the air in your house.

Heat Exchanger: Located in the furnace, the heat exchanger transfers heat to the air. The air is then pumped through the house.

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 your home’s your ducts. In the summer, it reverses the process and removes heat from your house and releases it outdoors.

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

Humidifier: A indoor air quality device that introduces moisture to heated air as it passes from the furnace into the ductwork for distribution throughout the home.

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

HVAC: Heating, Ventilation and Air Conditioning

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

MERV Rating: The MERV (Minimum Efficiency Reports 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, the higher the efficiency.

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

Odors/Chemicals: Air contaminants in the form of gases.

Particles: Any substances measuring less than 100 microns in diameter. The EPA has found that small 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 your HVAC equipment.

R-22 Refrigerant: The old standard for residential air conditioners, R-22 refrigerant is now being phased out by the U.S.

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

Refrigerant: 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.

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

SEER: The Seasonal Energy Efficiency Ratio is an energy efficiency rating for air conditioners. The higher the SEER , the better the energy performance, the more you save. The DOE’s established minimum SEER rating for cooling is 13.00.

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

Split System:  An HVAC system in which some components are located inside the structure of the house and some are located outside. Split systems should be matched for optimal efficiency.

Thermidistat: Monitors temperature and humidity and adjusts heating or cooling system to maintain desired levels.

Thermostat: Usually found on an inside wall, this device operates as a control to regulate your heating and cooling equipment, allowing you to adjust your home comfort at the touch of a switch.

Ton: Unity measurement for determining cooling capacity. One ton equals 12,000 Btuh.

Upflow: When an air handler or furnace is installed in an upright position.

Variable Speed Motor: A motor that automatically adjusts the flow of warm or cool for for ultimate comfort.

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

Zoning:  A method of partitioning a home into independently controlled comfort zones for enhanced comfort and efficiency.


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Marv M. Terre Haute, IN Oct 10, 2014

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