Glossary of Terms

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AFUE: Annual Fuel Utilization Efficiency. Indicated as a percentage, your furnace’s AFUE tells you how much energy is being converted to heat. For example, an AFUE of 90 means that 90% of the fuel is being used to warm your home while the other 10% escapes as exhaust (combustion gas).

Airflow: The distribution or movement of air.

Air Conditioning and Refrigeration Institute (ARI): ARI is an industry trade association that develops standards for measuring and certifying product performance.

Air Filter: Mechanical device in a forced air heating system used to capture particulate in an HVAC system. Air filters are always found on the return side of an HVAC system. They are usually located in the equipment itself, the return duct at the indoor unit, or in the return grilles in the living area. Filters come in many styles, sizes, and efficiencies.

Air Filtration: Mechanical means of filtering particulate out of an air stream in an HVAC system.

Air Handler: The indoor portion of your air conditioner or heat pump system that forces air through the structure’s ductwork system.

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

Boiler: A closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications. Boilers usually use wood, natural gas, propane, or oil as their fuel source.

BTU (British Thermal Unit): The amount of heat needed to raise the temperature of one pound of water one degree Fahrenheit. BTU is used to signify the heating and cooling capacity of a system and the heat losses and gains of buildings and homes.

BTUH: The number of BTU’s produced in one hour.

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, colorless, tasteless, poisonous, and flammable gas that is produced when carbon based fuels burn with insufficient air.