Smoke Billows Out

[EPS]

This may seem like a novice question, but we've been heating with a woodstove for about six years now and nothing like this has happened unti recently:

My wife has had plumes of smoke billow out of the woodstove as she is lighting kindling for a fire. All of the paper and wood in there is dry (or at least seemingly) but it is weird that it comes out the door rather than up the flue. Any thoughts on why this has happened and how to correct it?

 

[fire_man]

Sounds like the draft reversed since the flue was cold or maybe an exhaust fan was running in the house.

 

[Rickb]

Its called a reverse draft. I get it sometimes on a cold stove. I use a torch pointed up the flue for 10 - 15 seconds to get the draft going the right way.

 

[begreen]

If the stove has been working fine until recently, there are a number of factors to check. Start with the chimney cap screen and check to see if it is getting clogged. If there is a horizontal section of stovepipe check it for accumulation.

I don't recall what stove you are burning in. Is there a baffle blanket?

 

[firefighterjake]

As mentioned . . .

1) If it was moderately warm outside it could be a reversed draft. I get this in my own woodstove in early Fall and late Spring sometimes if the temps outside are relatively close to the temps inside.

2) If it was not moderately warm outside I would take a look at the chimney, cap, stove pipe and make sure there are no blockages from creosote, fly ash or some other debris.

 

[EPS]

Reverse draft it is! I will follow these tips to avoid them in the future. Thanks, Gentlemen

 

[begreen]

Reverse draft it is! I will follow these tips to avoid them in the future. Thanks, Gentlemen

@EPS What triggered the reverse draft? What stove is this? Does it have an outside air connection?

 

[jetsam]

Middle of december is not when we expect to hear people having reverse draft for the first time in 6 years (that's more of a warm weather thing).

I would inspect the flue from stove to cap, and think about depressurization (have you tightened up the house recently, added an exhaust fan, etc).

 

[Rickb]

Mine will have reverse draft on a cold stove any time of the year on a rare occasion tho it seems to happen more often when it is raining for some reason. Tho I have never had a draft reverse with the stove even slightly warm ussually only happens if the stove is not in use for at least a few days.

 

[jatoxico]

Sounds like the OP is happy but as a long time sufferer I'll add my 2 cents.

I think reverse draft and sluggish draft are sometimes used interchangeably but are from different sources which may both contribute to varying degrees depending on conditions and setup. Warm weather certainly can result in sluggish draft in an otherwise normally well behaved stove or fireplace due to lack of a pronounced temp differential.

Reverse draft, resulting from stack effects is a different animal altogether and often is often more pronounced and harder to overcome as it gets colder. Heat loss causing volumes of air to escape through the top of a structure needs to be replaced and often finds that the path of least resistance is through the chimney. This can result in flow that can be very strong. Under the right (wrong ) conditions the air rushing down the flue when I open the door of my insert can eaily be felt on the back of my hand and con even move ash in the insert. It usually gets worse as it gets colder although atmospheric conditions also seem to play a role.

I once had a full on reversal meaning the air feeding the fire to support combustion was coming from the flue. This was a scary situation which clearly showed me how little rope gaskets do when really pressed into service.

The draft doesn't care which direction it goes in but temp differentials between the envelope of the structure and the outside are the drivers. If your stove is below the neutral pressure plane like mine you know what I mean.

 

[SpaceBus]

Sounds like the OP is happy but as a long time sufferer I'll add my 2 cents.

I think reverse draft and sluggish draft are sometimes used interchangeably but are from different sources which may both contribute to varying degrees depending on conditions and setup. Warm weather certainly can result in sluggish draft in an otherwise normally well behaved stove or fireplace due to lack of a pronounced temp differential.

Reverse draft, resulting from stack effects is a different animal altogether and often is often more pronounced and harder to overcome as it gets colder. Heat loss causing volumes of air to escape through the top of a structure needs to be replaced and often finds that the path of least resistance is through the chimney. This can result in flow that can be very strong. Under the right (wrong ) conditions the air rushing down the flue when I open the door of my insert can eaily be felt on the back of my hand and con even move ash in the insert. It usually gets worse as it gets colder although atmospheric conditions also seem to play a role.

I once had a full on reversal meaning the air feeding the fire to support combustion was coming from the flue. This was a scary situation which clearly showed me how little rope gaskets do when really pressed into service.

The draft doesn't care which direction it goes in but temp differentials between the envelope of the structure and the outside are the drivers. If your stove is below the neutral pressure plane like mine you know what I mean.

Earlier this year I experienced a total draft reversal on my cookstove and I could not overcome it at all and had to toss the splits outside. This was caused by loading the splits onto my kindling fire before the stack of cold air had evacuated the flue. Pretty much like you described. When my cookstove is 100% cold I can even feel some cold air escape like you mention, but not a continuous draft, unless I light a fir and create a pressure change. Usually opening my patio slider about an inch or so is enough to increase house pressure enough to over come the cold air issue on lighting the stove. This never happens with my Morso, but it is on an interior chimney. Sometimes I wonder about adding a 1-2' class A section on the bottom of my cleanout tee to create a dead space like my interior chimney has.

 

[jatoxico]

I could not overcome it at all and had to toss the splits outside

Yeah, fun stuff!

In my case my insert is on the lower level of multi story house, sorta of walk out basement (even though I have a true basement as well). I used to think a brisk burn of kindling and paper would overcome it but once the air fully rushed backwards on me I realized too late that's not always gonna happen. Now I won't start a fire anymore until I'm sure I've got things headed in the right direction.

 

[SpaceBus]

Yeah, fun stuff!

In my case my insert is on the lower level of multi story house, sorta of walk out basement (even though I have a true basement as well). I used to think a brisk burn of kindling and paper would overcome it but once the air fully rushed backwards on me I realized too late that's not always gonna happen. Now I won't start a fire anymore until I'm sure I've got things headed in the right direction.

Indeed, I'm pretty cautious after that one total reversal. The flue outlet on the cooker is only a few feet from our slab and then it goes out the wall and straight up. I though this would work well for draft, but maybe I should have made the penetration higher up on the wall and ran an indoor tee. To my mind less bends is more better, but only having 18" of the flue indoors is maybe not the best?

 

[coaly]

Indeed, I'm pretty cautious after that one total reversal. The flue outlet on the cooker is only a few feet from our slab and then it goes out the wall and straight up. I though this would work well for draft, but maybe I should have made the penetration higher up on the wall and ran an indoor tee. To my mind less bends is more better, but only having 18" of the flue indoors is maybe not the best?

How much is the horizontal run pitched upward toward chimney? Without enough vertical rise off stove it probably needs more pitch. Double wall pipe inside makes a difference with low, through the wall installations too.

 

[SpaceBus]

How much is the horizontal run pitched upward toward chimney? Without enough vertical rise off stove it probably needs more pitch. Double wall pipe inside makes a difference with low, through the wall installations too.

There is a slight pitch, but not as much as I wanted. This past summer I wanted to adjust the opening and raise the Tee an inch or so. I basically have the Class A connected directly to the appliance with a transition, no double wall or single wall. After getting the moisture out of the refractory liner/insulation in the stove last fall/winter and learning how it likes to start/burn I have had very few smoky incidents. Of course the earlier mentioned total reversal being an exception. Hopefully next summer I'll get to the chimney adjustments and get put a liner in our masonry chimney.