Fisher smoking out of intake

There seems to be no correlation to outside temperature. It has been below 40 the past few nights and it is just as bad as if it's over 50. My stove will definitely do what is shown in the video. The smoke venting issue occurs in a similar manner except instead of flames reaching out, it is smoke.
There is a baffle under the outlet but it does not extend out in to the firebox beyond what the outlet pipe itself does. It is it sits right under the outlet pipe.

 

Your chimney can be extended temporarily with a cheap piece of single wall stove pipe (connector pipe). That's probably what I'd try. If it solves the problem buy a section of Class A.

 

I am leaning towards what you and WeldrDave discovered, the gasket. The leakage is a feature, not a bug, if the stove was designed to run without it. Putting the gasket on "might" have made it better, but maybe not?

Any other modifications done to the stove or pipe/chimney?

 

^.....burning is when I've seen this.
One theory is: The fuel is smoking/off gassing faster than the chimney can vent it. The smoke builds up, pushes through the damper cutting off any incoming oxygen, the stove gasps a breath and back puffs, repeat. Makes sense to me.

 

Bushpilot: if some leakage around the door were necessary and might solve the issue, couldn't it also be solved just by opening the damper? i have used the stove without a door gasket and it seemed by all available indications to be just as air tight as with the gasket.


The theory of excessive off gassing sounds interesting. Opening the door resolves this because there is no restriction of air to carry the exhaust up the chimney. So the solution then would be to get the fore goingore slowly? It would also make since because during the time I was using this stove during which I didn't have this issue, when I first put it in, I was burning wood that was on the greener side which took a while to get burning. Now my wood is nice and dry and it really gets ripping fast. So I will try starting with less wood in the box at first to avoid too much off gassing all at once and see what happens. Thanks for all the suggestions.

 

Maybe the solution is to keep the fire burning (regardless of the load size) at a moderate rate, instead of letting it get too hot causing excessive off gassing. That's was I've seen but I've never burned a Baby Bear and every install is different.
With the pre-epa stoves I've burned with that style damper (I call them screw type dampers)- about one full turn open on a two damper stove, two full turns open on a one damper stove- for a moderate burn. After the fire gets established. Does that sound about right to you WeldrDave?
Slow1442 are you burning with the damper opened several turns?
Are you monitoring flue pipe or stove top temperature?

 

I usually run the stove about one to two turns out on the damper. That is once the chimney gets warmed up. Starting a fire with the door closed and low damper setting causes the MOST smoke venting into the house. I have found I absolutely have to let the chimney get good and warm before closing the door, however even after doing this I still intermittently get smoke from the intake. Maybe on the next night cool enough to burn I will try to make a video to show what it's like.
Also, I am measuring temperature from the stove pipe about 12 inches up stream. This is with a surface thermometer, not a probe.

Does anyone think that double walled stove pipe in place of my current single wall pipe might help this issue? I suppose that more heat up the chimney would result in increased draft.

 

First, the claim that no Fisher Stove requires a flue damper is false. (sorry Dave) It is a chimney control and is required in certain cases to control too much draft. It has nothing to do with stove make or model. The flue damper is a variable resistance. It controls velocity of rising gasses, which in turn affects the stove by reducing oxygen entering. When wide open it has no effect on the flow. So opening it fully is the same as removing it. There are reasons to have one in place. They are required in the installation instructions (making it code) on the Series III double door models. It becomes the only control for open door burning with screen in place. The flue damper is integral on the Fireplace Insert and required by installation instructions for mobile home models such as Goldilocks. The ONLY models that do not require flue damper is the single door stoves from the Bear Series. UNLESS there is too much draft that needs to be controlled.
First, when starting with cardboard and kindling, you may get a roar up the stack. This looses a lot of heat which could be used to preheat larger wood pieces in the stove much faster. When you hear it roar, close flue damper slowly until the roar stops. This is close to the correct draft. This is NOT the time to slow fire by reducing air at intake. This practice reduces oxygen to the fire which needs as much as it can get when starting. (This is a good way to start less than desirable wood with a double door stove by putting screen in place so it can get as much air flow as possible and control excess flow with flue damper) Slowing the flow through stove will start the larger pieces faster than letting too much up the stack.
During normal use when up to temp, it should be open unless you have too much draft.

Second advantage having a damper is when fighting a piece that won't fit or taking extra time with the door open for any reason. This becomes your only control to slow oxygen through fire. If a chunk of your gasket falls off, how are you going to slow it down? Consider the flue damper as the emergency brake. During a chimney fire, putting water into the stove causes steam to slow the fire. You're going to wish you had a flue damper to shut when you need to open the door hearing that jet engine in the chimney. It does no harm to have it there if not needed. A Sooteater cleaning tool even goes around it making it unnecessary to remove for cleaning.
Another advantage is during coal stage. With no smoke present, you can close damper fully to extend fire duration. Heat output is low, but it can hold a pile of coals longer if it's already warm in the home and you don't need to start it for a while. You'll notice stack temp is the same before and after flue damper showing it doesn't "stop" heat, it slows velocity.
Older dampers will have a metered hole in the center and are sized for the draft required by appliance when fully closed. This is more critical burning coal (another Fisher Stove that requires a flue damper) or during open door burning with the Fireplace Series. Fireplace Insert models have them integrally installed with a metered opening when closed.

The second claim that no Fisher requires door gasket material is false. (sorry again Dave) All glass double doors require gasket material. Series III gasket is installed on the stove, centered in iron door channel seal. Series IV is installed on the door.

Door gasket; remove it. There is absolutely no clearance for gasket material between door and stove seal. (unless hinge pins or hinge plate is worn beyond limits) The raised portion on back of door makes contact in the center of iron door seal channel. The edges of door seal channel make contact on the back of door. Remove all cement with wire wheel and buff inside of door at sealing area. The gasket puts pressure on hinge pins, door hinge ears and latch rod. They are considered air-tight as built.

Your problems are due to the rising gasses stalling in chimney or out gassing of flammable gasses too rapidly from fuel. This is more pronounced in the Baby Bear due to a smaller firebox. The speed at which it does this are clues as to the cause. Go back to the basics of what makes it work. Rising gasses lighter than outside air rise up the flue creating a low pressure area in connector pipe and stove. (the lowest pressure area being at stove connector) Atmospheric air pressure is greater than inside the stove, and PUSHES into the stove intake. This pressure differential is very slight and measurable at the flue collar in inches of water column. Each appliance requires the proper pressure for correct flow through firebox. Your differential pressure is not enough. Could be weak due to not enough height, not enough heat in flue, or mechanical fan or blower in home not allowing enough higher pressure outside the intakes to push into stove.
What happens is the rising gasses slow for whatever reason. (when you figure it out, it will be cured) As they stall, lighter gasses build up and rise up the flue. (not necessarily out) Each time they stall, cooler heavier air drops down the chimney. This cooler air dropping supplies oxygen at the stove outlet. Preheated smoke particles and combustible gasses from fuel light violently causing increase in pressure which puffs out the intake as well as out the exhaust, rising up chimney to only fall back with another gulp of oxygen. You get the chuffing as the flow moves up and down instead of always moving upwards. This is back puffing and is slower than a flutter which is what the video shows due to out gassing of fuel requiring more oxygen than it can get through one small intake. If this is your scenario (faster than a chuff) and indoor pressure is correct (no radon fan, other fossil fuel burners or mechanical blowers exhausting indoor air, lowering the indoor atmospheric air pressure at intake) Your fuel is out gassing too rapidly for the small intake. This is why Baby Bear is more susceptible to this condition than the larger fireboxes with two intakes getting a better oxygen mix with the flammable gasses. Try a fuel mix with higher content moisture or test with kiln dried scraps to see if rapid burning makes it worse. You should be able to replicate this with any stove using too much cardboard and one intake open.

I tested all the Fisher models on the same 6 inch Dura-Vent chimney when designing baffles for the single door stoves. With 9 feet of chimney (3 sections) the Baby Bear is the only model I had issues with an unsteady burn. Cracking the door changes flow and gives it more air. Removing your gasket may allow leakage to produce turbulence which is the way to get oxygen to mix readily with flammable gasses being expelled from wood.

The most common cause for this problem with the Baby Bear is not enough stove for the chimney. In other words, not enough heat from the smaller fire is allowed up for enough draft. How many square feet are you heating? I want to make sure the stove is sized properly for the area.

Also are you burning on 1 inch of ash accumulation? This will slow the fire and the out gassing in case your fuel is too dry.
You should make sure you have minimum 15 feet from stove floor to top of chimney.

What Selkirk product are you using? Supervent is the norm and comes in 3 foot sections. Do you have two 3 foot sections making it 6 feet of chimney? How far above roof line at penetration and how far from peak, wall or slanted roof? This is where the Baby Bear becomes problematic with chimney height. The higher the chimney, the more draft, BUT the increase in draft is not proportionate to rise since the higher you go, the more cooling, so the higher chimney also requires more heat for the same draft. Baby Bear isn't always capable of more heat, hence my statement of "not having enough stove for the chimney".
Pictures of outside and house configuration is needed to alleviate the possibility of stack effect which is another cause of low pressure outside stove at intakes. Remember, it's not only the low pressure needed inside stove, but the differential pressure between inside and outside of stove that makes it work.

Slow1442, The reason it stops when opening door is the increase in area you give atmospheric pressure to push in with. The size (square inch opening) of air adjustment is how much it allows the higher pressure to push into the void or slight vacuum. Remember atmospheric pressure is measured per square inch pushing downward and in all directions. It is trying to get to the stove collar where the pressure is the lowest. An open door allows that, and of course also allows all the expanded gasses to rise out the stack along with the heat.

 

You guys are great, keep up the good work. OP I think you can get your Fisher going correctly.

 

You just forgot about the first style chain control damper on the first Inserts that was changed to the handle control. Here's a Fisher damper, handle and side mount plates with hardware; Notice the back half doesn't close the pipe completely and is the metered opening.

Now you saw one.

Anyway, all glass doors get a gasket. Here's the older III style on Insert and Honey Bear;

Insert with Series III doors.

Original gasket on my Honey Bear that only had a paint curing fire in. There wasn't even ash between the bricks when I took them out !

The later IV with larger glass has no door seal channel iron. Flat stove face like the last Honey Bears and TF-88.

Grandma IV (All Series IV are glass)

Late Convertible Honey Bear. (removable pedestal for mobile home and factory built housing use)

And of course the "toilet seat door" Arctic Flame or "The Flame" designated TF-88;



You can say ewww.

 

I can now say I've seen a Fisher I don't like.

 

Made by the designer on the West Coast (a trucking company that hauled stoves for Fisher) and only 50 made on the East Coast by Fisher Stoves S.E. in 1988. It was the last try at an EPA certified stove. They were not certified but could be sold until June 30, 1991.



Probably as close as you're going to get to the first secondary burn stove. This one did NOT sell on eBay back in Feb. 2013. Had my sights on it and couldn't pull the trigger.

 

Coaly: thanks to you (and all the others) for all the info. To answer a few of your questions: I have about 6 feet of single wall stove pipe and 8 feet of chimney pipe, all straight. This extends out of the roof by about 3 feet, clearing the peak by 2.5 feet or so. Roof is slanted. my house is just about 1000 sq/ft, though it's kind of shotgun style so claiming that I heat the whole house with wood is a little overboard because the far end will need a little help no matter the stove I believe. But this stove does pretty well. I typically do burn on at least 1" of ash.

I can report that after considering recommendations from this thread so far I have been able to greatly reduce my issue. I start fires smaller with kindling and one decent log rather than a box full of logs to reduce the initial off gassing. I also leave the door open for at least 10 minutes or more, until the chimney reaches 450-500 to promote good steady draft. By not adding wood too fast the air typically keeps moving the correct direction now. I still get some shuddering or oscillating (cannot think of a good word for this rapid in and out that makes a quick thumping noise) at times but for the most part it is without the previously problematic off gassing in to the house so it is of no concern.