My fisher stove

[cmferrante]

When we bought the house last year, it came with two wood stoves. A cute little jotul in the living room with a glass front and can only take 14" logs, although rated for around 1000sqft, which is perfect for our small house, on cold nights it's just not enough. In the basement came a giant stove which we burn for a couple days and it heats the whole house from the inside out. But being so large, we don't use it that much. Since finding your forum and learning more about burning wood and setting the fire correctly, we burn a lot less wood FAR more efficiently.

here is my fisher. Pretty sure it's a Momma Bear. measuring in at 30" back to front edge of plate.
Very curious as to how old it is. I also found it's missing the second row of bricks inside, but no clips to hold a second row of bricks either. Is the gasket supposed to be on the door, or the door jam? I took the old one out to replace from the jam, but found a large amount of epoxy in the door groove as well.

 

[coaly]

Welcome to the forum, Yes it's a Mama Bear.
No gasket material is required. Sometimes you can scrape or chisel the old cement off if it is deteriorated enough. Otherwise, wire wheel all gasket cement or glue off both door and stove. It must be clean metal to metal contact. The door seal is the iron channel iron welded to stove front that makes contact in 3 places all the way around. It is air tight as designed. The raised portion on back of door makes contact in the center of door channel and the channel edges make contact on the back of door on both sides of the raised portion. All those contact points must be clean.
Not all stoves have the second row of bricks. Many don't and they work fine without.
You have the first stainless steel door handle spring and early 4 fin draft caps; probably '76 or '77.
Keep the door hinge pins and draft cap bolt threads coated with high temp grease or silver anti-seize and it will outlast you.

 

[cmferrante]

Welcome to the forum, Yes it's a Mama Bear.
No gasket material is required. Sometimes you can scrape or chisel the old cement off if it is deteriorated enough. Otherwise, wire wheel all gasket cement or glue off both door and stove. It must be clean metal to metal contact. The door seal is the iron channel iron welded to stove front that makes contact in 3 places all the way around. It is air tight as designed. The raised portion on back of door makes contact in the center of door channel and the channel edges make contact on the back of door on both sides of the raised portion. All those contact points must be clean.
Not all stoves have the second row of bricks. Many don't and they work fine without.
You have the first stainless steel door handle spring and early 4 fin draft caps; probably '76 or '77.
Keep the door hinge pins and draft cap bolt threads coated with high temp grease or silver anti-seize and it will outlast you.

Great! I have a couple cracked bricks inside...I might try replacing them all. We have a couple wood stove places local I'm going to see if they have the right size bricks. These might be all the original bricks.

 

[coaly]

Cracked is not a problem until they are missing chunks. Not a fun job, but not difficult.
They are a standard fire brick. Most masonry supply stores have them. $1.50 around here. Ace Hardware sells them by the case that comes to $3.00 each.

 

[cmferrante]

So I'm fairly new to heating with wood. Is it correct to get the stove going good then use the damper on the exhaust to get it around 600oF exhaust temp. Then turn the draft caps till the stove is about 600. Or should I've running it higher? Or different? I am aiming for using it efficiently.

 

[coaly]

I'll clip and paste the basics here so you don't get confused if you're not sure what makes the stove work first;
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The most important thing to learn is that the chimney is the most important and the chimney is what makes the stove work.

Rising hot gasses in the exhaust are lighter than colder outside air. (outside of the flue) This temperature difference is what makes the exhaust rise up the chimney flue. This is called draft. This causes a low pressure area in the stove, like a vacuum.

Atmospheric air pressure pushes into the stove to fill the void created by chimney. This air feeds the fire oxygen to make it go.

The damper in the pipe is used to slow the chimney or reduce draft IF you have too much draft.
No one can tell you where to set it, since there are many factors and every chimney and vent system is different. It even changes with temperature and weather as in low pressure areas moving over your house. The lower the atmospheric air pressure, the less push you have going into stove. So it would need to be open more to increase the rising gasses or increase draft.
That was clipped from another thread that explains it well.
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In answer to efficiency;
Flue temp required is keeping internal flue gasses above 250* to the top when producing smoke. This prevents condensing water vapor in flue that allows smoke particles to stick to flue walls forming creosote.
So the heat allowed up the stack depends on your chimney. The flue damper is used to slow draft when and if required.
I know you have a rear vented Mama Bear with 6 inch outlet. I don't know if a baffle has been added, but that is the best place to start to gain efficiency.
You can do that depending on chimney, since the baffle reduces flue gas temperature slightly. You may need that extra heat loss allowed out if you don't have an efficient chimney. The stove efficiency starts with an efficient chimney. If you don't have that, you need to allow much more heat up, decreasing overall stove efficiency.

These factors are what you need to consider to estimate the heat needed to allow up stack to stay above the 250* threshold. A good insulated flue may only require 300 or 350* at chimney inlet compared to an oversize flue (larger than stove outlet) and very tall with no insulated liner requiring twice the amount of heat to keep above the 250*.
Pipe and flue diameter? (flue shape and size is very important)
Chimney height and type ; (indoor or outdoor)
Is this a masonry chimney, lined or insulated liner or insulated metal chimney.
Keep in mind if you are using a surface thermometer on singe wall pipe, the actual inside flue temp can be double surface temperature.
The pipe damper slows velocity up flue - which affects the stove by slowing air coming in through intakes. You may or may not be able to close damper depending on chimney. (a big chimney that needs tons of heat may need to be left open or you will form creosote rapidly. Check frequently until you are sure how much creosote you create.
Notice these questions are all about the chimney and venting system. Only allowing enough heat out to prevent creosote is efficiency. Stove top temperature is what is required to heat the area. (opening air intakes more for more output)

 

[coaly]

Once you understand the basics, you may realize the little jotul may be connected to a flue much larger than the stove outlet. If so, the gasses expand going into the larger flue and cool as they expand. This decreases draft slowing fire. The main concern is that it then requires lots more heat left up to heat the large chimney flue (above 250*) to keep it going strong enough to heat the indoor area. A smaller stove is more critical to have the correct size flue since the heat wasted up flue to keep it hot is all it has, and you'll feel output just isn't enough. It's usually due to needing so much left up the stack the smaller stove doesn't have enough usable heat for inside the house. Is that smaller jotul connected to the same diameter size flue as the Fisher? A larger chimney flue doesn't mean stronger draft. It means it is CAPABLE of more draft when more heat is left up.
You can only compare the two stoves when they are both connected to the proper size chimney each requires.

 

[cmferrante]

the jotul is connected to a full stainless liner. 6" inside the masonary chimney.
The fisher is connected to i believe, 6" square stove brick up the chimney from the basement of a 1 story home.