Q: Jason, One of the fireplaces in our 1844 house has an oven built into the fireplace hearth face, which we’ve never used. The oven has a door, and there is a clean-out door below the oven door. Can you make a guess if the Chimney Balloon would seal off the oven as well as the fireplace in one shot? Thanks, MB

A: Dear MB, A picture is worth a thousand words. Thank you for that photo of the hearth fireplace oven.

Sealing both with one Chimney Balloon is not recommended since you don’t know how high up the connection may be in the flue. I would sell them individually.

On the fireplace…I would measure the area where the fiberglass is at (I can see the yellow sticking down just below the lintel). I understand that is a trapezoid shape, so you will need a measurement of the front, the back, and the depth of that flue opening.

If this main fireplace flue has a fireplace damper you will also want a measurement above the damper since that may be a better location to install a Chimney Balloon if the damper hardware is in the way in the lintel area. Sealing the large flue is the main issue and that will stop most of the air infiltration, so let’s do that first.

If you still have the draft coming through the hearth oven then we can do a separate Chimney Balloon for that inlet. My suggestion for the oven would be to measure the shoot that runs out of the top or side of the oven enclosure. It should be a smallish rectangle or square vent heading up like a chimney.

With those measurements, we can get this fireplace air sealed, so the cold draft is not an issue anymore. – Jason