Backdrafting on Mama Bear

[Mama Bear in Northern WI]

Bought our house 11 years ago and it came with a wonderful Fisher Mama Bear whigh we usee to heat our 1200 SF home in nother WI. Haven't had a single issue with it until this winter. It is backdrafting smoke every time I open the door regardless of how hot/fast the fire is burning.

Two thoughts:
1) Is there something inside the stove like a baffle that could have slipped and now it's not drawing as well?

2) Is it more likely that something is wrong with my chimney? We have it professionally cleaned and inspected annually for our homeowners insurance.

I appreciate any thoughts on this matter. It's -16 here this morning and I need my stove to stop smoking me out!

 

[Todd67]

Welcome to the forum!

Sounds like a tough situation. Hopefully someone with more knowledge will be along soon to help you fix your issue.

 

[bholler]

Bought our house 11 years ago and it came with a wonderful Fisher Mama Bear whigh we usee to heat our 1200 SF home in nother WI. Haven't had a single issue with it until this winter. It is backdrafting smoke every time I open the door regardless of how hot/fast the fire is burning.

Two thoughts:
1) Is there something inside the stove like a baffle that could have slipped and now it's not drawing as well?

2) Is it more likely that something is wrong with my chimney? We have it professionally cleaned and inspected annually for our homeowners insurance.

I appreciate any thoughts on this matter. It's -16 here this morning and I need my stove to stop smoking me out!

The chimney is much more likely cause

 

[Don H]

Did you change the type of wood your burning? Is it dry and seasoned?
What type of chimney, masonry or insulated pipe? Is the chimney clean?

 

[Corey]

Anything which changed could be a culprit. One key thing is to determine if it is really 'backdrafting' - meaning air actually being pulled back down the flue...this would be most notable when the stove is cold - you'd feel major cold air coming down the flue and even a hot fire may not be enough to reverse it. This is in contrast to 'spilling smoke' - meaning the stove just can't draft enough to keep up with the fire output. In this case, when the stove is out, you'd still have a weak draft pulling air up the flue.

True backdrafting could be brought on by any physical changes... a clothes dryer, bath fan, change to the weatherstripping / insulation of the house, furnace, water heater, add a door, move a door, etc?

Smoke spilling is different. That could be creosote buildup in the flue, or chimney cap, possibly a loose or missing fitting in any clean out or T fitting, a bunch of creosote flaking off and landing on top of the baffle, or a critter or bird in an unwanted spot, etc.

Overall - same result - smoke in the house, but two totally different things and sets of causes.

 

[Mama Bear in Northern WI]

Anything which changed could be a culprit. One key thing is to determine if it is really 'backdrafting' - meaning air actually being pulled back down the flue...this would be most notable when the stove is cold - you'd feel major cold air coming down the flue and even a hot fire may not be enough to reverse it. This is in contrast to 'spilling smoke' - meaning the stove just can't draft enough to keep up with the fire output. In this case, when the stove is out, you'd still have a weak draft pulling air up the flue.

True backdrafting could be brought on by any physical changes... a clothes dryer, bath fan, change to the weatherstripping / insulation of the house, furnace, water heater, add a door, move a door, etc?

Smoke spilling is different. That could be creosote buildup in the flue, or chimney cap, possibly a loose or missing fitting in any clean out or T fitting, a bunch of creosote flaking off and landing on top of the baffle, or a critter or bird in an unwanted spot, etc.

Overall - same result - smoke in the house, but two totally different things and sets of causes.

Thank you! It's definitely smoke spilling and my guess is a new chimney cap was installed last year. We are going to pull it off and see if it helps.

 

[Mama Bear in Northern WI]

Welcome to the forum!

Sounds like a tough situation. Hopefully someone with more knowledge will be along soon to help you fix your issue.

Thank you! I love forums and that folks are willing to share their knowledge and experience.

 

[Todd67]

Thank you! I love forums and that folks are willing to share their knowledge and experience.

I've learned a great deal of knowledge on this forum. That's why I keep coming back

 

[coaly]

Is there a screen at the top?
After ice storms or blowing wind across the chimney top, it is very common to have creosote stick to the screen closing it off.
This is due to water vapor that is created by combustion rising with the smoke particles. The temperature of flue must remain above 250* to the top to prevent condensing of this water vapor. When smoke is present, the unburned smoke particles stick to the wet surface forming creosote. The coldest area is the screen which is the first to accumulate. The type, height and diameter of chimney flue determines how much heat you need to leave up.
Adding a baffle in the firebox increases firebox temperature burning more smoke particles reducing the particulate available to cause creosote.

The next common cause is cleaning a chimney and not removing the creosote, soot or ash from vertical pipe or elbow partially blocking the flow. This would be the same as closing a flue damper too far.

 

[Mama Bear in Northern WI]

Thank you everyone that offered their knowledge. Husband crawled up on the snow covered roof and popped off the new chimney cap and no more smoke coming out of the stove. It's been an unusually cold winter even for northern WI and I think we've had more than usual creosote build up. Our fabulous Fisher is back to its old self!

 

[Todd67]

I'm glad it was a simple fix. It's been a colder than normal winter in northern NY too.

 

[coaly]

Your problem was due to excessive resistance decreasing draft.
We don't know if your chimney is masonry or metal prefab. Both should have a cap of some sort to keep water out.
The cap should be designed to have no less square inch opening than stove outlet and flue diameter.
If it has a screen, was the screen clogged?

 

[Don H]

Just because you pulled the cap and relieved the symptoms doesn't mean you cured the patient.