Room above room with Quadrafire 7100 stinks of smoke.

[tiff]

The family room fireplace (never used) shares a chimney with the basement quadrafire 7100. The basement doesn't smell when a fire is burning, but the family room smells strongly. The room above that does
Not smell. We have put insulation above the damper in the family room fireplace and taped a plastic sheet over the fireplace opening to keep the smell contained. The plastic pushes out from a draft. I'm sick of this smell and worried my furniture, drapes, etc will soon be ruined. What on earth causes this? The chimey is 50' from the ground so a sweep going up there now isn't happening in our snowy, icy weather. There is no clog, we have smoke coming out of the chimney and the stove is burning fine. Please help!

 

[JA600L]

What kind of chimney is this? Clay lined or so liner?

 

[bholler]

Sounds like you are getting smoke being pulled down that fireplace chimney for some reason when you sealed the opening did the smell go away? You may need to raise the top of the stove chimney or just install a top sealing damper

 

[Grisu]

The Quadra 7100 is a ZC fireplace and should have a metal flue. When you say it shares the chimney with the upstairs fireplace do you mean the upstairs one is also a ZC fireplace with a metal flue and both are in the same chase? Otherwise, I would say your installation is not up to code.

Is your house rather airtight? It sounds like the 7100 pulls in combustion air through the flue of the upper fireplace. That would explain the plastic pushing out from the fireplace. Installing an outside air kit to the 7100 will help with that. Both flues should also have a different height and not terminate at the same level.

 

[tiff]

We have an outside air thing installed. They each have their own flue. The quadrafire flue is metal, double lined.

 

[Grisu]

I think the 7100 uses an air-cooled chimney. Is the outside air supplying air to the flue or the firebox?

How close together are the flue terminations on the roof? Do you have a picture?

Are you using the upstairs fireplace? If not, you could just close off the flue completely and that should solve the problem.

 

[tiff]

The outside air is supplying air to the firebox.
We have never used the family room fireplace. The flue is closed and there is insulation above it to seal away the smell. It's obviously not working.

 

[begreen]

It sounds like the Quad chimney may need raising. Are the two chimneys terminating at the same height and close to each other?

 

[tiff]

The chimney caps are several feet higher than the top of the chimney. They do not share anything. They are the same height, however. The quadrafire has a metal cap on it required for it. The other unused fireplace just has a clay pot.

 

[bholler]

So is the other fireplace a masonry unit? or is it a prefab fireplace wit ha metal chimney as well?

 

[begreen]

The chimney caps are several feet higher than the top of the chimney. They do not share anything. They are the same height, however. The quadrafire has a metal cap on it required for it. The other unused fireplace just has a clay pot.

That probably is the problem. Adjacent flues should not terminate at the same height. Add a 12-18" section of pipe to the Quad flue. Or lower the clay tile pipe if possible.

from the extendaflue site:
Negative pressure within the home can suck smoke from the top of one chimney flue to be sucked down an adjacent, unused flue. This is a common occurrence and may result in multiple problems...from smoky smells in the house to actual poisoning of the residents!

 

[tiff]

The other fireplace is a masonry fireplace. Our house is new construction and we have never used the family room fireplace. It is set up to be wood burning or gas, but neither has occurred yet.

Nobody told us the flues should not be the same height. I will look into extending the Quadrafire flue and also putting a permanent damper inside the top of the family room fireplace. Do they need to take the clay pot off to do that? How do you operate it from inside the house? Thanks to all of you, by the way.

 

[tiff]

I forgot to ask, why is there air coming in from the family room fireplace though? Surely the flue heights have nothing to do with that, right?

 

[bholler]

Have you had a sweep out to evaluate the issue? And just because it is winter does not mean that a sweep cannot get up there. I go on roofs all through the winter and i am sure that there are sweeps in your area that do the same. If you have not had a pro out yet you need to. I think that you probably need to extend or shorten one of the flues. But i am not sure why you have such a strong back draft on the fireplace chimney That would not be caused by the flues being the same height.

 

[Osagebndr]

Sounds like, and I may be wrong but the one is actually down drafting from the other, but like I said I may be wrong

 

[Stoneduster]

Do you suppose the stack effect is in play here? Perhaps the family room is in a high negative pressure zone of the house. If you crack a window in the family room, does air come rushing in?

 

[tiff]

We did have one out and he said because of the height and weather he couldn't go up to investigate and clean the chimney. It's a 50 ft tall chimney that we either need a scaffolding for or need to rent a lift to access. We've had a snow and ice-covered ground consistently.
What causes back drafts?

 

[Grisu]

With a new construction your home may be pretty airtight. Any appliance that moves air outside (range hood, bathroom fan, furnace, 7100...) will generate a negative pressure in the house. The flue of the fireplace may be the entry with the lowest resistance to get outside air in. You may not usually notice it as much when the 7100 is not burning as there will not be any smoke smell. Maybe a cold draft coming from the fireplace but that will be it.

Did you not have a very long flue on the 7100? Potentially that has such a strong draft that when you are running the 7100 the OAK is not enough and the combustion air needs to be made up from the upstairs fireplace. Since you are already pretty much at the max for the 7100 I would consider extending the fireplace flue or potentially capping it off altogether if you don't have any current plans for using it.

 

[bholler]

What causes back drafts?

There can be lots of causes but the most common is negative pressure in the house

 

[JA600L]

I would get a piece of foam board insulation board and cut it to fit.

The insulation is just acting as a filter. You need to air seal it. Temporarily you could Crack a window close to the stove to take some of the negative pressure away.