Barometric draft controls stabilize the draft to any appliance located below it.
A counter-balanced flap opens and shuts depending on the strength of the negative pressure (draft) in the chimney. As the flap opens (with greater draft), more air is let into the chimney, thereby decreasing the draft to the appliance.
Barometric Draft Controls have adjustable weights which allow the units to be set for the particular draft required. They will do an excellent job of maintaining the draft setting within reasonably close tolerances except when the total draft in the chimney drops below the setting on the barometric draft control. The draft control can only decrease draft, it has no ability to increase draft. In cases of excessively strong draft, two barometric controls in series may be required.
Barometric Draft Controls are completely assembled and are constructed with 24 gauge metal.
When used with woodstoves, the connector pipe and flue must be inspected and kept clean. A barometric draft control can potentially lengthen and intensify any chimney fire by allowing an unlimited supply of combustion air.