Furnace Filter Glossary

The following are definitions for common terms related to furnace filters.

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Air

The mixture of gases that make up the atmosphere; ~78% nitrogen, ~21% oxygen with the balance consisting of smaller amounts of gases including argon, carbon dioxide, neon, helium, and other gases.

Air Change

A measure of the amount of air moving in or out of a space because of leakage or mechanical ventilation. One air change is a volumetric flow of air equal to the cubic content of the space.

Air Cleaner

A device used for the removal of particulate or gaseous impurities from the air.

Air handler

An air moving and/or mixing unit. Residential air handlers include a blower, a coil, an expansion device, a heater rack and filter. Heaters for air handlers are sold as accessories. In some models heaters are factory installed.

Air Filter

A device for removing particulate material from an air stream.

Ambient Air

Refers to untreated air existing in any location.

ASHRAE

American Society of Heating, Refrigeration and Air Conditioning Engineers, Inc. This organization historically sets standards for low and medium efficiency air filters.

Blower

A fan used to move air under pressure.

CFM

Abbreviation for cubic feet per minute, a standard measurement of airflow. A typical system requires 400 cfm per ton of air conditioning.

Controlled Environment

An environment in which parameters such as temperature, pressure, humidity, contaminant level and so forth are controlled within specified limits.

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