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The most common furnace humidifier is the bypass humidifier. It makes use of the pressure
differential between the return and supply plenums on a furnace to move air through it with
minimal electrical consumption. Constructed of metal or plastic, it consists of a cabinet,
reservoir, rotating drum with motor, and float. Preferably mounted on the supply plenum,
warm air forced into the cabinet and flows over the rotating drum. The drum is a sponge
or foam fabric stretched over a plastic frame. A small motor slowly spins the drum through
a tray of water fed from the domestic water supply and regulated by a float valve. As the
wet drum is exposed to the flow of warm air, water evaporates and humidifies the air. Ducted
into the return air plenum, it is mixed with supply air and ducted to the house. |
