A Portion of All AGL Proceeds Support Charitable Causes


Reversing Valve

A device in a heat pump that reverses the flow of refrigerant as the system switches from cooling to heating.

Return Air

Air drawn into a heating unit after having been circulated from the heater’s output supply to a room.

Residential Wine Coolers

Wine cellars that are cooled separately from the rest of the home.

Relative Humidity

The ratio of the amount of vapor contained in the air to the maximum amount the air could hold at that temperature, usually expressed as a percentage.


Combination grille and damper assembly covering an air opening or end of an air duct.

Refrigerant Lines

Set of two copper lines connecting the outdoor unit and the indoor unit.


A substance that produces a refrigerating effect while expanding or vaporizing.

Radiant Floor Heating

Type of heating that can be combined with geothermal systems to warm a home’s floors.