Fisher smoking out of intake

Hi all. First time poster.
I'm looking for some advice on an issue I'm having with my fisher baby bear. I put the stove in last year and at first had no issues with smoking. Everything worked great. Toward the end of the season the stove started having strange fits where it would start billowing, or pulsing, at high frequencies and producing a LOT of smoke out of the damper. Now getting started this season it seems to be even worse. Opening the door resolves this issue but of course it begins to over heat the chimney promptly. I have tried both opening the damper and choking the damper down but when the stove starts to do this there is no setting which will stop the smoke. I have confirmed that there is no restriction in the chimney. The chimney consists of about 6 feet of single wall stove pipe and 8 feet of chimney pipe, all straight. This issue will occur at low chimney temps and high chimney temps. Outdoor temperature seems to have no effect on it as well. I have ensured that there is ample intake air available by opening windows and even doors in the interest of experimentation. This will happen just after start up as well as several hours in to a burn. there seems to be no real pattern to it. it just happens sometimes. What could I do to stop this stove from pushing smoke out of the intake?

 

When you say "damper," I am assuming you mean inlet air. If you mean you have a key damper on the outlet, that first needs to go.

Back puffing can be caused by air starvation, in combination with a weak draft. Your chimney as described is likely marginal in height, with the singlewall making it worse.

When you open the door, the air starvation is temporarily solved, but as you say, it is too hot. Closing the door allows the very hot fire to "get ahead of the stove" creating a lot of woodgas in the firebox, which cannot exit well enough due to the weak draft. It builds in the firebox until it flashes, causing the puff. The flash pushes smoke out through the inlet and up the pipe, which then allows more woodgas to build for the next flash.

First make sure the chimney is clean, if not then cleaning it might make the difference you need. Then, I would improve the chimney, and I think you will see the problem diminish or disappear.

One other thought - I have read that if your splits are real small and quite dry, they can gas quite quidkly, overwhelming the stove. What is your wood like?

Welcome to the club!

 

Welcome, can you post some pictures?

 

Thanks for the responses all. First let me answer a few questions:
No, there is no key damper on the outlet. Last year I had one but I found it of no use so I got rid of it this year.
The chimney is clean. I cleaned it before the first burn this year. I completely replaced the stove pipe to attempt to clean it up some.
I'm burning dry (12-18%) wood. I do tend toward smaller splits because of the small size of my firebox. I burn a mix of woods right now. Mostly walnut at the moment, some Holly and beech. Type of wood has shown to have no effect however.
Wind: I have noticed this issue to occur whether there is wind or not. The chimney is on what is typically the windward side of the house however. It is close to the peak, but the minimum 2 feet of clearance (I believe it was 2. Whatever it was I surpassed it by 6") is observed. There is a rain cap on the top. This is the standard cap that comes with the Selkirk kit.
I will post some pictures shortly.

So from what I see in the responses, i could consider switching to double wall stove pipe or lengthen the chimney. I initially theorized that single wall pipe would be good for me because the stove is slightly on the small side for the house I'm heating and the single wall pipe would radiate more heat. If double wall pipe would solve this issue I would certainly transition.
How much height would need to be added to the chimney to make a difference? Would an additional 2 feet make a notable difference? With the cost of chimney pipe I don't want to do any more experimenting than necessary! But I will definitely do what I need to.

I have been experimenting with attempting to increase draft by letting the stove pipe get hotter before closing the stove door when starting a fire. This seemed to work at first but still sometimes after letting the stove pipe reach over 500 degrees the stove will get silent for a few seconds after closing the door and then billow smoke profusely. The one thing I must do to mitigate the issue is close the intake damper completely when closing the door and let the burn slow. Then I open the damper slowly and typically there is no exhaust.

 

For some reason my picture is not uploading. I am able to select it as an upload but it just doesn't happen. Maybe I'll try on a real computer tomorrow.

 

Hi slow1442
Welcome to the forum.

What size is the outlet on the stove?
What size is the flue pipe?

 

The outlet, stove pipe, and chimney pipe are all 6".

 

Welcome to the Hoard Slow1442 .
I've seen/had this happen on pre-epa stoves. Seems to be caused from a small smoke explosion (back puff) followed by a gasp for air which causes another small smoke explosion. The cycle begins. The solutions are usually-crack the door (which causes things to heat up fast) or shut the dampers down, as you've already tried. If closing the damper doesn't work, I'd suspect the stove is leaking/drawing a lot of air around the door. It requires oxygen to have a smoke explosion.
Why the need to "completely replaced the stove pipe to attempt to clean it up some"?
Have you recently checked the chimney cap? They can plug up in days under the right (wrong) conditions.

 

my thoughts also.
I also think this could happen just because the air control/intake is so close to the fire being right on the front of the door. On our Fireview the air intake is on the back of the stove and the air travels over the top and is entering the firebox at the front at the top of the glass. No way for it to puff back out the intake since its so long and makes a steady flow of air.

check this out

 

This stove exits out the rear. What I meant by "cleaning up" the stove pipe was mostly removing the restriction of the key damper. It was also just instead of cleaning the old pipe. The door on this one does not leak any. I have a flat gasket in it that helps it seal nicely. When I close the intake damper it pulls no air at all and produces no smoke.

 

If I'm understanding you right, isn't this the solution?

 

Well sure, but it's comparable to just not starting a fire in the first place haha. To clarify, closing the damper completely and opening it slowly usually acts as a short term fix for me. At any time during the burn up until I'm left with only embers, the smoke may flare up out of no where whether I have closed the damper or not.

 

Maybe I don't understand where the smoke is coming from

 

I am aware that the fisher does not require a gasket and that it will seal without, but is it doing any harm to have one so long as it is thin enough to allow the door to shut completely? I figured it could only help.

 

Does the outside temp have any affect on the back-puffing? As you probably know, the warmer it is the weaker the draft.
How does yours look compared to the video posted, is it a rapid back puffing like in the video?