How hot should the cathedral box get above the woodstove?

[T Dog]

I have installed a cathedral box on a cabin I recently purchased. The original owner had a somewhat home made set up. Everything is as it should be now, but the bottom of the box is about 32 inches from the top of the stove. The front and sides of the box get pretty warm. You can rest your hand on it but can not leave it there very long. The back of the box stays cooler as it is not directly above the stove. Is this safe? Thanks!!

 

[begreen]

That's warm, but probably ok. It would take an IR reading to be sure. The 32" distance seems close. What stove is this and how far from the stove top to the ceiling?

 

[T Dog]

That's warm, but probably ok. It would take an IR reading to be sure. The 32" distance seems close. What stove is this and how far from the stove top to the ceiling?

It is an older Fisher stove, maybe 4 feet to top of ceiling. Thanks for the quick reply.

 

[moresnow]

4 feet to the ceiling? Must be a monster Fisher! Or a rather low ceiling?

 

[T Dog]

4 feet to the ceiling? Must be a monster Fisher! Or a rather low ceiling?

Right, make that about about 5 feet!

 

[begreen]

Single-wall stove pipe to the box? If so, the heat off the stove plus heat radiating off the stove pipe could be warming up the cathedral support box a bit more than normal.

There is chimney pipe from the support box up through the roof, right? Is the chimney pile reasonable new class A pipe and is it in good condition?

 

[T Dog]

Single-wall stove pipe to the box? If so, the heat off the stove plus heat radiating off the stove pipe could be warming up the cathedral support box a bit more than normal.

There is chimney pipe from the support box up through the roof, right? Is the chimney pile reasonable new class A pipe and is it in good condition?

Yes, it is single wall stove pipe and the insulated pipe through the ceiling and above the roof line is brand new. Would it help to use double wall pipe?

 

[begreen]

Good that there is new chimney pipe. Could be the stove is sending a lot of hot gases up the flue pipe. Do you have a flue thermometer? If so, what does it read about 18" above the stove? What does it read if you put it on a warm spot on the chimney support box?

Is the Fisher baffled? Is there a key damper in the flue pipe that gets closed down once the stove is burning well? Either/both may reduce heat going up the stack.

 

[T Dog]

Yes, it is single wall stove pipe and the insulated pipe through the ceiling and above the roof line is brand new. Would it help to use double wall pipe?

Good that there is new chimney pipe. Could be the stove is sending a lot of hot gases up the flue pipe. Do you have a flue thermometer? If so, what does it read about 18" above the stove? What does it read if you put it on a warm spot on the chimney support box?

Is the Fisher baffled? Is there a key damper in the flue pipe that gets closed down once the stove is burning well? Either/both may reduce heat going up the stack.

It is baffled, have not heard of a flu thermometer yet (new to the wood world) will pick one up. No key damper (again not sure what that is exactly) What kind of temperatures should I be having ideally 18 inches above stove and on box?

 

[begreen]

Flue temps will vary depending on the stage of the fire. You want the flue temps to be high enough to keep creosote from forming during the outgassing stage of the burn (strong flames). And surface temps on a single-wall pipe are about half of what the internal flue gas temp will be. So a reading of about 300F = an approximate 500-600F reading inside the pipe. A safe range to run the stove flue temps at would be in the 200-400F surface flue temp.

A key damper is an adjustable damper that is placed in the stove pipe , usually about a foot after the flue collar on the stove. Closing once the fire is burning well slows down the flue gases and allows more residency time in the firebox for more heat and complete combustion there. Here is what they look like. Most hardware stores have them.


Moving this thread to the Fisher forum so that you can get some real world operational temps from users.

 

[coaly]

I have installed a cathedral box on a cabin I recently purchased. The original owner had a somewhat home made set up. Everything is as it should be now, but the bottom of the box is about 32 inches from the top of the stove. The front and sides of the box get pretty warm. You can rest your hand on it but can not leave it there very long. The back of the box stays cooler as it is not directly above the stove. Is this safe? Thanks!!

The bottom of ceiling support box can not be 32 inches from stove top. That only gives 34 inches to ceiling where box extends a minimum of 2 inches below finished ceiling. You have a 48 inch clearance to combustibles in Canada. That means measuring anywhere on the stove to unprotected combustible material must be over 48 inches in your case, 36 in US. (depending on model, clearance could be less if this is a UL listed stove with shields)

 

[T Dog]

The bottom of ceiling support box can not be 32 inches from stove top. That only gives 34 inches to ceiling where box extends a minimum of 2 inches below finished ceiling. You have a 48 inch clearance to combustibles in Canada. That means measuring anywhere on the stove to unprotected combustible material must be over 48 inches in your case, 36 in US. (depending on model, clearance could be less if this is a UL listed stove with shields)

I am estimating the dimensions, from the top of stove to the bottom of the adapter from single wall to cathedral box is 3 feet and then the box extends about a foot. I stayed a minimum of 18 inches from the walls that will be covered with durarock and a heat shield on the closest side.

 

[T Dog]

I am estimating the dimensions, from the top of stove to the bottom of the adapter from single wall to cathedral box is 3 feet and then the box extendsView attachment 198134 View attachment 198134 about a foot. I stayed a minimum of 18 inches from the walls that will be covered with durarock and a heat shield on the closest side.

I really appreciate the help! I am pretty new to the wood burning and am very interested in it but am concerned about lack of knowledge and safety,

 

[begreen]

Make proper wall shields for close clearances.
https://www.hearth.com/talk/wiki/build-a-wall-shield/

 

[coaly]

That is either a Goldilocks or Teddy Bear. Teddy was more common in Canada.
Goldi will not have air holes through doors. Only the left knob turns and the entire stud the knob is mounted on protrudes through the door to push on a tab that opens a flap across stove front behind doors that allows all intake air up through pedestal. Goldi also has an ash clean out under ash fender.
They are mobile home certified and require the base to be raised a minimum of 1 inch off floor for intake air in your installation.

Teddy will have holes through doors behind intake dampers and both draft caps (dampers) rotate to adjust intake air.
The manual for both is in the sticky section at top of the home Fisher Forum page and the Teddy manual includes Canada. I believe yours will be 7 inch outlet on stove if it's a Teddy.
The bear in my avatar was given with Teddy Bear Stoves for a period of time in Canada. They are a Ganz teddy bear and quite rare.

 

[T Dog]

Flue temps will vary depending on the stage of the fire. You want the flue temps to be high enough to keep creosote from forming during the outgassing stage of the burn (strong flames). And surface temps on a single-wall pipe are about half of what the internal flue gas temp will be. So a reading of about 300F = an approximate 500-600F reading inside the pipe. A safe range to run the stove flue temps at would be in the 200-400F surface flue temp.

A key damper is an adjustable damper that is placed in the stove pipe , usually about a foot after the flue collar on the stove. Closing once the fire is burning well slows down the flue gases and allows more residency time in the firebox for more heat and complete combustion there. Here is what they look like. Most hardware stores have them.
View attachment 198131

Moving this thread to the Fisher forum so that you can get some real world operational temps from users.

Thanks so much!