Sealing an ash pit door

[Simpson]

In our 1972 home we have two fireplaces (main living room and basement), the main fireplace has a little door at the bottom back that we believe to be an ash pit door. The problem is every time we make a nice fire, after 45 minutes the basement starts to fill up with smoke.

We don't need that opening, and my only guess is that is how it is making its way down there. Can we pull out that door and have a mason seal that area shut with firebrick?

Alternatively, i've thought about using a silicon sealant with a piece of steel plating to close it off that way. Would that be safe? In the next few years i'm hoping to put in a fireplace insert in.

 

[DAKSY]

You can stuff some unfaced fiberglass insulation or some rockwool down in the opening & leave the door in place or you could stuff unfaced insulation behind the lower door in the basement...

 

[bholler]

In our 1972 home we have two fireplaces (main living room and basement), the main fireplace has a little door at the bottom back that we believe to be an ash pit door. The problem is every time we make a nice fire, after 45 minutes the basement starts to fill up with smoke.

We don't need that opening, and my only guess is that is how it is making its way down there. Can we pull out that door and have a mason seal that area shut with firebrick?

Alternatively, i've thought about using a silicon sealant with a piece of steel plating to close it off that way. Would that be safe? In the next few years i'm hoping to put in a fireplace insert in.

I would say it is more likely that the smoke is being pulled down the flue of the basement fireplace than going down the ash drop. I guess the ash drop would be possible but very uncommon. Pulled down the other flue is pretty common on the other hand

 

[Simpson]

I would say it is more likely that the smoke is being pulled down the flue of the basement fireplace than going down the ash drop. I guess the ash drop would be possible but very uncommon. Pulled down the other flue is pretty common on the other hand

This is really helpful, I would have never thought this. Is a chimney balloon a good solution to fix this?

 

[bholler]

This is really helpful, I would have never thought this. Is a chimney balloon a good solution to fix this?

They are not a permanent solution but it would tell you if that is the issue. You could also tape something over the top of the flue as well to find out if that is what is going on. If it is a top sealing damper on the basement fireplace would be a permanent solution.

 

[begreen]

Are the two flues of equal height at the top of the chimney? If so, raising the main floor flue by 12-18" can help cure this problem.

 

[Simpson]

Are the two flues of equal height at the top of the chimney? If so, raising the main floor flue by 12-18" can help cure this problem.

Yes I think they are the same height

 

[begreen]

This product is designed to address the problem.
http://www.extendaflue.com/products/extend/extend-a-cap.html

 

[bholler]

This product is designed to address the problem.

That can work but I would recommend covering the unused flue first to confirm that the problem is smoke being pulled down that flue. If it is and you don't use the lower fireplace much I would recommend a top sealer. That will stop the problem and they seal much better than the throat damper to reduce heat loss out of the house.