Grandma Fisher.

Hi folks I have been creeping around here for some time now and thought I would sign up to ask a few questions. I have loved fisher stoves since I have seen my first grandpa bear up north at my neighbors cottage.

The grandma bear I have I use to heat my shop with, is new to me this year. I have a good draw with a 6" pipe exhaust out the top with a 6" pipe dampener about 20"s above stove top. There is 10 feet non insulated into the insulated pipe out through the wall and up another 15 feet. I have taken the advice I have read on here about adding a smoke shelf or baffle in her. This alone made a very big difference on how well she would heat and burn cleaner.

My question is about adding secondary burn tubes. I build staircases for new homes and renovations in my shop full time all the time. I have end cuts of oak, hard white Maple, brown maple, and 50% white pine. All my lumber is 9% max moisture. I will burn about one cord of cut fire wood and this year I have some maple and red elm. The problem with this fisher, that is new this year to me, is that I can't load her up with a load of my stair cut offs with out it roaring like a dragon. Flames out the dampeners and some blue smoke back into the shop. If I crank down the primary air knobs she will just about snuff out and not make heat. I have a very hard time with my cut offs letting her go. If I do with the door open a crack say 1/2" she will get up to 600* on the deck quick and the stove pipe will run up to 450*s. I close the door and she will bark like a train and spit smoke till the flame is just about out.

Will adding secondary burn tubes stop or prevent this roar or fire breathing of this fisher? The doors are very air tight I can choke the fire just about right out but she will creosote up really fast. I find that if I close the pipe dampener right off and leave the primary air open 3/4 turn min 1 full turn max over night I can keep coals over night. I find creosote on the doors if I turn her down below 3/4 turn with a full load for over night. If left at 1 full turn the doors are a nice tan brown in the morning with a few coals left. That seems to be the sweet spot.

For how much scrap wood I make I would really like to get the fire dragon under control so the pine would throw heat but not back bark smoke into the shop. I can't get the pine to crank heat and not bark smoke into the shop. Thoughts? maybe is poor operation on my part?

Cheers Don.

How did you operate the dampener? I just put a brand new 6" one in the stove pipe about 20"s above the stove. I just can't seem to get the pine rocking where it throws heat with out it blowing smoke rings out the primary air in.

I expect that secondary air will help this but just guessing at this point and not sure if I want to mod this stove or just put a bit of the pine in with more logs.

Cheers Don.

Do you really think a tighter dampener would be the trick? I do have a brand new dampener in the 6" un insulated pipe it has some factory holes in it but it dose fit in the 6" nice and tight.

My thoughts after reading all about this secondary air that this may be what I need. I do not want to get into all the work if its not worth the time to invest into secondary air build/retro fit.

Cheers Don.

coaly said:

Welcome to the forum,
"The problem with this Fisher" is probably not the Fisher............

Lack of air for the fuel load? (opening door corrects)
More fuel, more air = more heat until you reach the capacity of chimney draft.

Reduced draft = reduced air
Sounds like you're pushing the stove beyond the chimneys limits?

I assume this stove has an 8 inch outlet reduced to 6 ?

Is the operation normal with firewood? (the only fuel recommended in manual) and would require less air ?

Did it do this before baffle was installed? (another slight exhaust restriction)
And how much smoke space (opening dimension above baffle plate) is there? The opening for smoke to travel between plate and stove top needs to be 50 plus square inches with 8 inch outlet, 28 plus square inches with 6 inch outlet stoves.

Sounds like the highly volatile cut offs may require the full 8 inch flue? The exhaust restriction maybe doesn't allow the expanding gasses to get out fast enough??

Try cutting back on dimensional lumber fuel load to see how much is acceptable for your given draft. (correct the fuel / air ratio and not get much heat)

Cause #9 here? http://www.hawk.igs.net/~sunworks/backpuff.html

Click to expand...

Yes the stove has a 8" off the top and this is where I reduced it right away to 6". Yes the stove works great with normal firewood. I can get a nice clean burn with the two air control knobs turned one full turn out over night. Inside of the doors are nice and tan, and the ash is pure white in the morning.

Above the baffle from the top of the baffle to the top of the stove I have about 2.25"s and the stove is 23.75"s wide in the inside. Do you think moving the baffle up closer to the stove top for the 6" pipe exhaust? I would need about 1.19"s or 1.25"s in there.

Yes I have found that if I stack the cut offs tight with no spaces between them they will burn more realistic and not like there is gasoline in there.

I do have what I would call to much draft for the pine cut offs. Imagine that you filled the stove with cardboard with the air vents open two full turns and let her go.

See when I choke down the air this chugging stops till it gets going again at that setting and then I need to close them more till I have them closed to the point I can't seem to get heat of the pine. If I leave the door open the stove will shoot to over 600 (heat guns limit) and the pipe to 450. I am kind of worried of letting her go with one of the doors open a bit and the fan on the stove for fear of a spark jumping out in a wood shop.

Here is my thoughts. I should burn this highly fast burning wood with the dampener closed to slow the exhaust down but crank open the primary air? Let the fuel have as much air it can take but slow the draw of the air with the exhaust.

I think I just need to learn how to burn this fast burning fuel cut offs.

Cheers Don.

coaly said:

I'd try raising the baffle from about 1.25 to 1.5" smoke space with 6 inch flue.

When firing a locomotive with coal.............. one trick when needing fuel in the firebox, but already having a clean hot fire not needing more heat, is to wet the coal down in the tender before shoveling it on. Try soaking some in a bucket and use when the moisture content is closer to your firewood??

Click to expand...

So maybe going to 1.25" on the smoke shelf will help this too by slowing the air down? It is set about 2"s or more now. I can see this working better for sure because it will increase velocity of the gasses in that area than it is now.

With out the smoke shelf on this 6" pipe the stove was uncontrollable. I would not get even my normal firewood to burn with out it chugging and blowing smoke out the main air.

I think I will try to cut down some fire brick. Now I just put an extra row on their side to hold up the added smoke shelf.

Cheers Don.

coaly said:

If you have a masonry blade for a circular saw, a score line only 1/8 to 1/4" deep will allow you to snap the brick clean. They are soft and cut easy.

Click to expand...

Well the brick cut like butter with a sawzaw and a bymetal blade. Now what a difference having that smoke shelf the correct distance from the top of the stove. The space is now the same square inches as the 6" exhaust so the velocity is equal. My doors now on a full load are very light tan with a touch of white as well as the area where the exhaust needs to pass the front edge of the smoke shelf. I just lifted the front of the shelf as well so the 1" slope to the shelf helps burn the back of the wood load first as well as the front the front middle is where my coals are left.

All I can say is what a difference in the stove. Clean burn and lots of good heat.

Thanks for all the help.

Cheers Don.