Chimney question

[Jackbnimble]

When the chimney is the same size as the stove pipe you can get back drafts on wind less nights. I installed many woodstove using 8" pipe stainless chimney with a 6" stove pipe. I have a book put out for woodstove safety and installations by the government. I know I see many woodstovrs with 6" chimneys. They complain about back drafts its dealer installed. Inspected by the towns code people too. If there's a fire the insurance company will inspect the installation with the fire department. I taught my towns code guy.

Spent a fortune on 6" stainless steel stove and chimney pipe​

years ago. Since than, I got a deal on a stove with a 8" flue opening. Can I run the 6" stove pipe from a 8" opening on this newer wood stove? New ss stove and chimney pipe to span 30' will run in the thousands. Thanks

 

[Ted Jenkins]

The design of the stove should dictate what size of flue to use. If your stove is set up for for a 6'' flue you can convert 6'' to 8'' with an adapter with out any problems. However a 8'' flue will not draw properly to some extent from a 6'' source. You could put a 6'' flue inside the 8'' pipe. You might be able to get a sheet metal shop to roll some stainless steel to install inside the larger flue. If you have several bends then that will cause plenty more issues. If the 8'' flue needs to make several bends that will cause all kinds of issues with the drafting. If you want good drafting under all conditions then design a mostly straight design with a smaller liner inside your larger flue. Thanks

 

[TRTermite]

House has two fireplaces, one up, one down. When making a fire in the upstairs fireplace, it seems like the lower one draws the smoke from the fire back into the house, from the top of the chimney.. The flues at the top are side by side and only maybe 8 inches apart.

. My theory is that when there's a fire, the negative air pressure is drawing smoke back in from the unused one, and since they are side by side at the top, it kinda makes sense...no? Downstairs, seems to get filled with the smoke odor....not so much the smoke itself.

The dampers are not the best, they're the old steel ones that close but don't seal air tight.

Any other ideas as to why this would happen?

Any possibility the unused chimney is colder? Does it draw a downdraft only on starting/warming other chimney? Side by side chimneys can be a challenge but you know that now.. Any updates on your experiments?

 

[TRTermite]

Spent a fortune on 6" stainless steel stove and chimney pipe​

years ago. Since than, I got a deal on a stove with a 8" flue opening. Can I run the 6" stove pipe from a 8" opening on this newer wood stove? New ss stove and chimney pipe to span 30' will run in the thousands. Thanks

I do. Be aware the UL has addressed this in a negative manner. Old Timer statement "A chimney can't be to tall or to small" Naturally some common sense needs to prevail and so many other factors.

 

[Jackbnimble]

I do. Be aware the UL has addressed this in a negative manner. Old Timer statement "A chimney can't be to tall or to small" Naturally some common sense needs to prevail and so many other factors.

Thanks.

 

[mga]

Any possibility the unused chimney is colder? Does it draw a downdraft only on starting/warming other chimney? Side by side chimneys can be a challenge but you know that now.. Any updates on your experiments?

i think i'm going to try this thing. seems simple enough to install found it on amazon. i just have to buy a 3 1/2 inch hole saw too.

this is my first time with a dual fireplace and it's on an outside wall. our last house was a single fireplace in the center of the house. being on the outside the damn thing is cold unless i put paper in there first to warm it up but still need a door slightly open because this house is air tight. even the dryer draws the smell of the fireplace into the house.