How to prevent cooling season stove stink?

[woodpile]

Hi all,
During the heating season, buoyancy creates a draft that sends the stove odor up the chimney to the outdoors. During cooling season, the reverse happens and the stove odor seeps into the living room. Are there ways to minimize this?

I have a Lopi Answer in the fireplace, with a partial flue liner in the existing clay flue tile lined chimney. In the past, I have tried a closed-cell foam plug to fit in the stove pipe. This did not work, and I suspect that enough air sneaks past it and also goes between the clay flue tiles and the liner, sneaking between the stove pipe and the baffle. I have considered burning a very hot, clean fire to drive off the volatile stuff that smells, but charcoal is all I can think of that would burn clean, and I don't know that it will be nearly as hot as a wood fire.

 

[begreen]

Plastic bag over the top of the chimney? Or a chimney balloon?
(broken link removed to http://www.chimneyballoon.us/chimneyballoon.html)

 

[bholler]

A light in the stove also works well and keeps everything nice and dry. Properly installing it with a full liner would also fix the problem. That would allow you to clean it better so there would be nothing to smell. It would also make it burn better again much less there to smell and much less chance of a reverse draft

 

[maple1]

I'm having a hard time grasping the concept of warm (lighter) outdoor air that would be at the top of the chimney dropping down the chimney & pushing the cooler denser air at the bottom out of the way. When you make a fire on in the winter it's often hard to get a draft established due to the dense cold air at the top - it blocks the flow. Same should apply in summer - cold air at the bottom should prevent the hot light air at the top from dropping.

I have never experienced this ('fire stink') here in 20 years - that's with a boiler in a cool basement at the bottom of a 30' chimney. Have also never seen any moisture at all in it.

But maybe I'm just lucky...

EDIT: Or, is it maybe not 'the reverse happening' (reverse draft down the chimney), but rather the absence of any draft at all to carry the smell up? Then it just kind of dissipates into the room? We've got a fireplace also in our living room, just keep the doors & dampers/drafts closed & no stink there either.

 

[gyrfalcon]

A light in the stove also works well and keeps everything nice and dry. Properly installing it with a full liner would also fix the problem. That would allow you to clean it better so there would be nothing to smell. It would also make it burn better again much less there to smell and much less chance of a reverse draft

I've sure never had this problem. Maybe that's why.

 

[bholler]

I've sure never had this problem. Maybe that's why.

Down drafts can happen even if everything is done right from many causes it is not common at all but it can happen. But if everything is done right it will not smell.

 

[gyrfalcon]

Down drafts can happen even if everything is done right from many causes it is not common at all but it can happen. But if everything is done right it will not smell.

Well, I'm sure glad I spent the money to have it done right when I decided to put in a stove.

 

[bholler]

Well, I'm sure glad I spent the money to have it done right when I decided to put in a stove.

Good for you I think it is well worth the investment.

 

[billb3]

Hi all,

I have a partial flue liner in the existing clay flue tile lined chimney..

That must stink .

 

[gyrfalcon]

Good for you I think it is well worth the investment.

Sometimes things work out best when you literally have no idea what you're doing and hire somebody who does and take their advice.

 

[bholler]

Sometimes things work out best when you literally have no idea what you're doing and hire somebody who does and take their advice.

Yes as long as you hire the right person

 

[woodpile]

It is the column of air in the chimney that creates the draft. In the winter, the chimney is warmer than the outside air because the house is warming it. I don't light a fire unless the outside air less than 45°F, else I do have lack of draft. I get stove stink when the house is at least 20°F cooler than outside, no breeze required. The chimney is on the south side, but shaded by ivy and a maple tree, so the sun does little to warm it.

 

[maple1]

I get stove stink when the house is at least 20°F cooler than outside, no breeze required.

That's kind of what I'm having a hard time understanding. The warmer (less dense) air is outside (at the top of the chimney), and the cooler (more dense) air is inside (at the bottom of the chimney) - so can't figure how the lighter air would want to fall down the chimney & how it would displace the heavier air at the bottom. The cold air at the bottom should act as a slug & block it.

Is there also maybe something going on that would create negative pressure in the house? Like a/c or ventilation exhausting air outside? Or maybe air blowing through the house (in one window & out another) doing a venturi thing?

 

[Oldman47]

The cold house is cooling the air in that chimney and it is sinking into the stove. What is hard to understand about that?

 

[maple1]

Well, in order for it to sink it would have to be cooler than the air below it. Would it not?

 

[Oldman47]

If you have x volume of air in the stack and you cool it, it will "shrink" and more air will need to come in the top to fill the space.

 

[maple1]

I could see that, maybe, but also thinking it should also reach an equilibrium when it will shrink no more - and would do so without pushing out the bottom. Unless the bottom was under a negative pressure.

I don't know - I just know that in 20 years I have never experience this phenomenon in this two storey house we're in, either from a boiler at the bottom of 30' of chimney or a fireplace at the bottom of 8' less chimney than that.

 

[woodpile]

The windows were closed and there was no blower - it was cold outside and that's were I wanted the cold to stay. Given that the chimney is on the outside wall and is uninsulated, after a cold evening it probably is colder than the inside of the house. It was in the 40's at night, the house stayed in the low 60's inside, and the outside warmed to the low 80's during the day. I get this reverse draft most every spring.

 

[brenndatomu]

Bath or kitchen fan may be pulling it in...

 

[Rossco]

Yeah could be a positive vs negative pressure problem.

Increase in pressure outside will push air into the house. Path of least resistance.

The only real way the air is transferring from the stove into the house is through the intake. Block this off, Unless you have an OAK?

 

[begreen]

Yeah could be a positive vs negative pressure problem.

Increase in pressure outside will push air into the house. Path of least resistance.

The only real way the air is transferring from the stove into the house is through the intake. Block this off, Unless you have an OAK?

That sounds more plausible, though it doesn't explain what makes some houses more prone to this than others? Open basement windows maybe?

 

[Rossco]

That sounds more plausible, though it doesn't explain what makes some houses more prone to this than others? Open basement windows maybe?

Yeah you bet. I had similar issues during the winter after i sealed the house tight, in the end I managed to draw air in and over the stove to slightly pressurize the house.

Even a OAK doesn't solve the problem of ambient / internal pressure differential.

Only thing I can think of if sealing the stove up or sealing the chimney off so air enters the home via a different route.