A family member has ran a Fisher grandma bear for the past 25 years at home....they are now wanting to get a new stove to reduce the clearance of the stove and gain a little more room in the living area. This is a through the roof job. For the grandma bear the pipe is all 8 inch. The new stove is 6 inch....all of the piping is very easily accessible. What are the options?
Pipe reduction 8 to 6 inch.....
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That sounds more like a pipe expansion - the stove has 6" on the outlet, you're going into an 8" chimney.
I've got exactly that situation running my Quadrafire 4300 into an 8" double wall flue. Seems to work fine, but I'd imagine it gets dirtier than it should due to the expansion in area the smoke is running through cooling it off on the way out.
Theoretically, you can overdraft your stove with that too, so you may want to run it by a qualified installer who can check out all the relevant factors like height, outdoor obstructions, elbows in the pipes etc.
I've got exactly that situation running my Quadrafire 4300 into an 8" double wall flue. Seems to work fine, but I'd imagine it gets dirtier than it should due to the expansion in area the smoke is running through cooling it off on the way out.
Theoretically, you can overdraft your stove with that too, so you may want to run it by a qualified installer who can check out all the relevant factors like height, outdoor obstructions, elbows in the pipes etc.
It might be ok to run the new stove on the 8" flue with an increaser. How tall is the flue? What is the make/model of the new stove?
The total length of all piping is about 11 feet. Straight up, no 90's or bends. It's a summer's heat 1800 square ft. Stove.
XmasTreefarmer
Feeling the Heat
Begreen's on the case here, but I'd check the Owners Manual for the new stove and see if they list a max chimney size for the new stove. For my Oslo that's right in the manual and I'm running my 6" pipe into a 7" poured, solid flue. That's within Jotul's specs and is working fine. Not knowing much ... the 11' of total piping - stove pipe plus chimney, might be a bit on the short side for sufficient draft.
That's a bad combo. 11ft is too short for almost any modern stove to perform correctly, especially in a mild climate. The Summers Heat stove will need 15' of flue and fully seasoned wood to perform well. In this case the increase to 8" is just going to make things worse.
Old stoves were not too fussy this way because they had no secondary combustion system and often no baffle either.
Welp, actually I just took a tape out there and there is a little over 16 ft of piping involved. That would be from the top of the new stove to the top of the chimney on the roof.
Much better. It's worth a try to see if it will work. Draft may not be ideal during warmer weather, but it may work out ok as long as the wood is fully seasoned.
In theory a rigid 6" stainless liner would work, but I am uncertain if there would be code implications.
Would you not reccomend just piping some single wall black stove pipe through the existing 8 inch pipe?
No, that is not a good idea. Black stove pipe is only allowable in the room and never meant to be used as a liner. Try it with the 6" to 8" increaser first. That is the least expensive option.
I will just second what begreen said try the increaser first. If that doesn't work you can line it but it needs to be done out of stainless.
I will add before doing anything be sure to fully inspect the chimney. They really are only expected to last about 25 years.
I will add before doing anything be sure to fully inspect the chimney. They really are only expected to last about 25 years.
I will try to post some pictures. There is really no "chimney " so to say. This is a mobile home that came with a fireplace. My grandpa had a guy come in and take out the "corner fireplace" and install an through the roof kit for the fisher grandma bear. So inspection should be fairly easy. Other than the part that goes through the roof the rest of it is 100% visible at all times.
Did they replace the old chimney for the prefab at that time or is it still the chimney from the fireplace? I am much more concerned with where it goes through the roof and the inner wall than the exterior.
It was all torn out and replaced. It doesn't go through a wall at all. Just the roof with the square metal boxing
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