Is an outside combustion air kit supposed to cool your house 24/7 even when the fireplace is not on? Regardless of where the outside combustion air lever is set, I get a solid draft into the house from the vents along the base and lower sides of the unit. Additionally, the whole hearth is cold, like outside temperature cold. It sucks the heat from that room, which is constantly 10°F cooler than the rest of the house. I covered the offending vents with duct tape which stopped a majority of the draft, but the hearth is still freezing cold. My uneducated guess is that there is outside air circulating throughout the hearth void (especially the 1' high ledge that extends out into the room by a foot below the fireplace). 10 year old home with a builder-installed Lennox Superior BRI-36 (BR-36 I suppose). Never turned the thing on during my 5 years in the house. I believe we have an outside combustion air kit installed (otherwise unexplainable vent at the base of the chimney).