Block second flu with expanding foam?

engrish?

Hi,

We have 3 chimneys in our house, two downstairs, one upstairs. I have boarded up one fireplace downstairs and the other downstairs one is in use as an open fire. The fireplace upstairs which is in a bedroom is open but not in use, only for aesthetics. The issue is that when I light a fire downstairs, sometimes the smell of burning can come out of the fireplace in the bedroom. I don't believe there to be a degraded flu, but I think it is happening because the chimneys are all the same height and the smoke is going out one and down the other. The house is very well insulated so this could be creating a drag down the chimney.

I would like to block the bedroom flu and I was considering using expanding foam as it would be easy to do. Would this be dangerous? Should I use cement or will the foam suffice?

Thanks,

Hoagy

Don't use expanding foam, it's not safe to use in an enclosed space and you'll never get it out again.

Get a chimney balloon like these

sky6

The best solution is to fit another pipe to the top of the Chimney.
If you are going to block the Chimney then better to use fiberglass as it doesn't burn.

antiskeptic

engrish? wrote: »

Hi,

We have 3 chimneys in our house, two downstairs, one upstairs. I have boarded up one fireplace downstairs and the other downstairs one is in use as an open fire. The fireplace upstairs which is in a bedroom is open but not in use, only for aesthetics. The issue is that when I light a fire downstairs, sometimes the smell of burning can come out of the fireplace in the bedroom. I don't believe there to be a degraded flu, but I think it is happening because the chimneys are all the same height and the smoke is going out one and down the other. The house is very well insulated so this could be creating a drag down the chimney.

I would like to block the bedroom flu and I was considering using expanding foam as it would be easy to do. Would this be dangerous? Should I use cement or will the foam suffice?

Thanks,

I'm wondering whether the air being sucked into the house via the burning fire isn't being sucked down the chimney (if (most) everything else is closed tight).

It can also be localised gusts at chimney level driving traces of smoke down the chimney upstairs.

Whatever, I'd use a soft child's football of suitable size (i.e. slightly larger in diameter than the flue pipe) pushed up and jammed at the entrance to the flue pipe. It's easy and cheap to apply, removable, fast.

I'd avoid chimney balloons as they tend to get sucked up the chimney - either disappearing with the wind, or getting lodged half way up. They only block the chimney about 80% anyway so you won't avoid the smell issue.

NIMAN

Try sticking an old pillow up it, should block out most of the draught, and cheaply.

engrish?

Thanks folks. My only fear with using something like a pillow is that some hot ambers would float up the fire chimney and down the ornamental one. I do have fiber glass left over from insulating the attic so I could use that if needed.

God I hate touching fiber glass - no matter what I do I seem to end up itching for hours!

sky6

Put it in a plastic bag first, that way you can pull it out for the Summer and have to put back for the winter again.
Even if an ember melted the bag it's no big deal.