1976 Comforter help

[jmcindric]

Hello. I'm looking for help on sizing the pipe for our 1976 Comforter wood stove. It has an oval opening in the rear that measures approximately 8-3/8" outside diameter wide by 6-5/8" outside diameter tall. This is our first wood burner and we will be putting in our hunting cabin, so bear with us as we will have more questions about piping the stove. Thank you!!

 

[Fire Water]

I own one , buy a 7“ 90 and shape it to fit,do know these stoves are a beast and run best with 7” or 8” pipe 6” really slows the stove down and makes lots of creosote and requires frequent cleaning with 6” pipe.
These are really well made American stoves I have had to stop using mine as it’s just to big for my house. One hour burn and the house was 90 degrees, it saddens me I couldn’t make it work in my house.
The 7“ 90 is the shortest way to go verticle but takes some skill in metal fashioning to get a nice smoke proof seal. I have used a 7” coupling fitted to the oval and a tee for clean out but this pushes the stove out with increased dimensions.
Pictured is a 7”X 6” reducing coupling fitted to accept a DuraVent 6” tee it worked ok . Originally my stove was installed with 8” pipe and ran beautifully . I relocated the stove and used 6” pipe with marginal performance and increased maintenance. I believe it is a Vermont casting makes several sizes and have some ovals that can be made to fit.

 

[coaly]

To make recommendations, we need to know the heating area, ceiling height and construction (insulation or solid wood walls) or BTU required. The vent system is what the makes the stove work. It is not just to let the smoke out. Start with what type and size chimney you have. Masonry or metal prefab, interior or exterior, with or without insulated liner.

The chimney creates draft, or low pressure area in flue, pipe and stove. The connector pipe reduces draft. You need to know what you need from the stove before designing the system.

Creating more creosote with 6 inch pipe is an indication of incorrect chimney sizing or uninsulated liner. The correct flue gas temperature determines creosote formation, a smaller connector pipe will not create more creosote connected to the same size chimney. Chimney flue, pipe and stove outlet should be the same diameter. It is technically against code to reduce the size from stove outlet. If this stove is oversized for the area, a 6 inch chimney and pipe may be fine for slightly decreased BTU output. A larger chimney has more capacity, but also take more heat to create more draft.

Sizing the stove to area heated is critical. Sizing the stove to chimney, or chimney to stove must be correct.

 

[Fire Water]

Excellent dissertation of flue requirements, I learned why I had problems with 6“ pipe . I did get it run decent and clean by removing a horizontal piece and using the side door for better draft.

 

[jmcindric]

To make recommendations, we need to know the heating area, ceiling height and construction (insulation or solid wood walls) or BTU required. The vent system is what the makes the stove work. It is not just to let the smoke out. Start with what type and size chimney you have. Masonry or metal prefab, interior or exterior, with or without insulated liner.

The chimney creates draft, or low pressure area in flue, pipe and stove. The connector pipe reduces draft. You need to know what you need from the stove before designing the system.

Creating more creosote with 6 inch pipe is an indication of incorrect chimney sizing or uninsulated liner. The correct flue gas temperature determines creosote formation, a smaller connector pipe will not create more creosote connected to the same size chimney. Chimney flue, pipe and stove outlet should be the same diameter. It is technically against code to reduce the size from stove outlet. If this stove is oversized for the area, a 6 inch chimney and pipe may be fine for slightly decreased BTU output. A larger chimney has more capacity, but also take more heat to create more draft.

Sizing the stove to area heated is critical. Sizing the stove to chimney, or chimney to stove must be correct.

Coaly

The area being heated is a 16' x 20' weekend cabin with a full loft or second floor if you will. Ceiling height is just under 8' on the first floor and 6'-6" on the second floor. The cabin is being built this fall so there is no existing chimney. This would be a "new" installation. I picked this stove up for a song before we knew what size the cabin was going to be. I was just trying to get materials sorted out for installing the stove so that I was ready when the time came. My plan was to run the chimney on the exterior of the cabin. What I don't want to happen is getting cooked out of the cabin when the stove is running, however it seems it might be too much stove for the space.

 

[jmcindric]

I own one , buy a 7“ 90 and shape it to fit,do know these stoves are a beast and run best with 7” or 8” pipe 6” really slows the stove down and makes lots of creosote and requires frequent cleaning with 6” pipe.
These are really well made American stoves I have had to stop using mine as it’s just to big for my house. One hour burn and the house was 90 degrees, it saddens me I couldn’t make it work in my house.
The 7“ 90 is the shortest way to go verticle but takes some skill in metal fashioning to get a nice smoke proof seal. I have used a 7” coupling fitted to the oval and a tee for clean out but this pushes the stove out with increased dimensions.
Pictured is a 7”X 6” reducing coupling fitted to accept a DuraVent 6” tee it worked ok . Originally my stove was installed with 8” pipe and ran beautifully . I relocated the stove and used 6” pipe with marginal performance and increased maintenance. I believe it is a Vermont casting makes several sizes and have some ovals that can be made to fit.

Fire Water

The cabin is only 16' x 20' with a full loft/second floor. I was afraid this might be too much stove for the space and from your experience it sounds like it may be.

 

[Fire Water]

Mine came with the house and I ran it the first time and wow an hour later I was headed for the basement and opened windows to let the heat out. Not a raging fire either ,enough wood to get a bed of coals to feed a log or two every once in a while. There’s a massive amount of surface area with a generous fire box and the normal operation I believe there in the 48K BTU range. Wonderful stove for a big room or house where the heat can get pushed around. Small fires in a big box are a pain to maintain .

 

[coaly]

Watch for a Fisher Baby Bear or equivalent if you want to stay with an older stove. That’s the smallest for up to 1000 sf. You have twice the stove you need there. A small fire in a larger stove doesn’t work well. You need a hot firebox to burn clean.

Use a stove with 6 inch outlet, and insulated 6 inch chimney.

A newer stove with secondary combustion will use less fuel, but arriving at a cold building requires a lot of heat quickly, which an older stove accelerates at. If this is a stick built with hollow insulated walls, stay with the correct size. If this is log construction, oversize for a weekend is fine since it takes a day to bring the temperature of logs up. Logs are very poor insulation, but radiate heat back into the building as well as radiate out. Once up to temp they require less to keep warm, so constant use requires a smaller stove compared to intermittent heating.

 

[jmcindric]

Watch for a Fisher Baby Bear or equivalent if you want to stay with an older stove. That’s the smallest for up to 1000 sf. You have twice the stove you need there. A small fire in a larger stove doesn’t work well. You need a hot firebox to burn clean.

Use a stove with 6 inch outlet, and insulated 6 inch chimney.

A newer stove with secondary combustion will use less fuel, but arriving at a cold building requires a lot of heat quickly, which an older stove accelerates at. If this is a stick built with hollow insulated walls, stay with the correct size. If this is log construction, oversize for a weekend is fine since it takes a day to bring the temperature of logs up. Logs are very poor insulation, but radiate heat back into the building as well as radiate out. Once up to temp they require less to keep warm, so constant use requires a smaller stove compared to intermittent heating.

Could, how about this Jotul 602? This seems like it might be just the ticket for what we need. Opinion?

 

[Fire Water]

Eight bolts and the stove is apart in six pieces with no gaskets except the door. I bought mine for $175.00 off eBay and was a bit of a drive to go get it. That one appears to the same condition as mine : see my Jotul 602 thread. I tore mine down and the screws for the flue were rusted up and tight some Kroil and a few taps will a ball peen hammer got them out. Both burn plates are cracked and are being replaced as you may find with that one so that cost is in addition. I rarely saw any under$5-600.00 on eBay . By all accounts they are a great stove with parts still available . We are both heating the same space and these 28K BTU stoves shouldn’t over heat the space.
BTW their is a insulating blanket that goes under the bottom burn plate they are $50.00 for a new OEM one mine was no good to reuse.

 

[jmcindric]

Eight bolts and the stove is apart in six pieces with no gaskets except the door. I bought mine for $175.00 off eBay and was a bit of a drive to go get it. That one appears to the same condition as mine : see my Jotul 602 thread. I tore mine down and the screws for the flue were rusted up and tight some Kroil and a few taps will a ball peen hammer got them out. Both burn plates are cracked and are being replaced as you may find with that one so that cost is in addition. I rarely saw any under$5-600.00 on eBay . By all accounts they are a great stove with parts still available . We are both heating the same space and these 28K BTU stoves shouldn’t over heat the space.
BTW their is a insulating blanket that goes under the bottom burn plate they are $50.00 for a new OEM one mine was no good to reuse.

Thank you Fire Water! It looks like I am missing the bottom burn plate, so I need to source one of those. I also need the Jotul pipe adapter. The stove looks to be in good shape. The side and top burn plates don't appear to be cracked or warped in anyway, but I do need to pull them, clean and look them over. Can you tell me if the top burn plate just rests on the side ones or is there a mechanical fastener attaching it to the side plates? Is it necessary to tear it apart and re-cement the joints? I did notice that the gasket around the door is rock hard, I am guessing it should have some give to it correct? Do you know what thickness gasket should I use? I appreciate all your information and help!

 

[begreen]

The "top burn plate" is the baffle. It rests snugly on the ridge at the back of the stove and on the side plate edges. The door takes a 3/8" gasket and should be pliant.

 

[coaly]

Could, how about this Jotul 602? This seems like it might be just the ticket for what we need. Opinion?

The reason I suggested a Baby Bear or equivalent is due to being steel plate stoves. You stated this will be for weekend use, so I'm presuming the interior or stove temp may be about the same as outdoor temps when you get there. A cast iron stove is not suited to go from 10 or 20*f. to 500 quickly. A steel plate stove is much more forgiving for your use. The larger the cast iron plate, (sides in this case) the more expansion from that piece. Steel plate stoves are one piece, welded together with no resealing of joints, and the right brand will not require any door gasket. They are very fixable, welded easily, and pretty much bullet proof. They can be dropped off a truck, bend a leg, be straightened and good as new. Not so much with a fragile cast stove.

Baffles in a steel plate stove are steel plate as well. They can be removed when cold, beat back into shape and reused. Keep the door hinge pins and intake dampers greased, and they are maintenance free.

The last Baby Bear I bought was $80 with bear paw feet. I sold the set of feet for $100. So I'm 20 bucks ahead for the stove!

When I get to my cabin in winter, I fire the stove lightly until hot to touch, then load and crank it up. You would want to fire a cast stove slowly taking more time to get heat into the home. Mine is solid logs 792 square feet. Baby Bear is for up to 1000 sf, but I use a Mama Bear for 1500 sf since I need more heat when I arrive and it has a larger stove top for my only cooking and water heating than Baby. If I was staying in it for longer periods of time, I have a much smaller Haugh's secondary combustion stove I would use to save fuel but not have the higher output. It takes 2 days to bring a log cabin up to temp, then takes much less keeping it there.

 

[begreen]

A cast iron stove is not suited to go from 10 or 20*f. to 500 quickly.

To a certain extent, it depends on the stove design and casting quality. Good cast iron is tough stuff. Cast iron car exhaust manifolds regularly experience this change.