When chimney pull rises on a cold or windy day, the gate swings open further and dilutes the flue gas with room air, keeping draft over the fire nearly constant. The counterweight is adjusted with a draft gauge to the burner maker's setting. It is standard on oil burners and some gas power burners, and it must be installed level and plumb so it swings freely.
Heard on the job
Barometric damper's painted shut, that's why the draft swings all over the place, free it up and reset it.
Insider tip
Set the barometric with the burner at steady state, not right after light-off when the chimney is still cold.
Also heard as
- barometric draft regulator
- baro
- draft regulator