Jotul F55

You can put a damper in the T connector right? When I get my new stove, that works be the only place I could put it. I currently have a stainless liner and can't do a damper in that.

clark77 said:

You can put a damper in the T connector right? When I get my new stove, that works be the only place I could put it. I currently have a stainless liner and can't do a damper in that.

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You may not need one. From another thread it looks like Knots has a top-vented F55 with the pipe going straight up. You will be rear-venting with a horizontal section plus a T-section (90 degree bend). That alone will mean your draft will be reduced.

Grisu said:

You may not need one. From another thread it looks like Knots has a top-vented F55 with the pipe going straight up. You will be rear-venting with a horizontal section plus a T-section (90 degree bend). That alone will mean your draft will be reduced.

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That's a good point. If need be, can it be done? I don't have any experience with them

Grisu said:

You may not need one. From another thread it looks like Knots has a top-vented F55 with the pipe going straight up. You will be rear-venting with a horizontal section plus a T-section (90 degree bend). That alone will mean your draft will be reduced.

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Correct. I just have a 26 foot straight shot. The chimney goes through the center of the house. It's warm for about 16 feet, the next 7 feet are in the attic, and three feet exposed.

Remember, local conditions can affect this also. I'm nestled next to a ridge line. This may affect things. I dunno.

Creekheat said:

Surprising it would run away with the air all the way down .

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The primary still allows some air in and the secondaries are unregulated. I've been repeatedly reminded here that you can't "shut this stove down". EPA and all that...

The Jotul manual states that the chimney makes the stove work, the stove does not make the chimney work.

So, when the stove designer sat down with a blank sheet of paper, he looked at the EPA test requirement, and the range of ambient temperatures and chimney heights and styles that were possible.

Then they picked air intake orifice sizes that would accommodate all of these variables and still perform. They probably picked the nominal condition and tried to have the primary adjustment accommodate most of the rest of the range. But remember, there's still that pesky EPA test that you must pass, and the EPA isn't going to allow you to modify the stove to pass the test. Compressible fluid flow is complicated (air is a compressible fluid) and we're just talking about rectangular holes for fluid control. To add to the variable influences, the air comes in a different temperatures and humidities based on the installation, further affecting the air density possibilities.

The orifice sizes allow for a certain air intake velocity (really mass air flow) based on how the chimney performs. The fire box is a fixed volume. So, for a 14' chimney with bends in the "Florida Bungalow" you get one mass air flow. For a 30' straight chimney in Alaska you get another. All feeding the same volume of combustibles.

For some reason, my 26', "warm", straight chimney performs near the right side of the bell curve - away from the nominal the designer used. As a result, I get a large MAF which makes it more difficult to meter the air.

For my fires yesterday, I "shut" the primary air, had the almost taped-off secondary, and had the flue damper closed (it still allows for some flow). I "shut down" at 450. The stove went to 675.

I don't have the level of control I would like, but these are the realities of my installation.

Creekheat said:

I'll be curious to see how my specific situation works. It will be a 26ft stack. Straight shot except for a bend to go around a roof rafter. The house is very well insulated and it's an alcove install with the class a running up through a stone chase. You can see some of it in my avatar. My exposed chimney and cap will be on the calm side of the house. We shall see

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I'd wait and see. There's a lot of variables that affect chimney performance.

With a new stove, I was in attendance during the entire first burn cycle. Gradually, after I got the secondary under control, I slowly increased the amount of time I was away from the stove.

I don't know if you can see it well in the pic, but the Tel Tru thermometer I have has a "tell tale" that shows the highest temperature during the cycle. This helps me a lot to have continued confidence when I'm not around. It's not a cheap thermometer, but it was worth the money for me.



If you search around on "F55" here, I think you'll find most other people have a different burn than me. The guy from NJ says he fills it up, runs hard to char all the wood, and then sets the primary to 1/3 and he's done. That's different than how my set-up works.