Flue Damper Too Small for Wood Stove 6" Liner

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Jsd245

Member
Dec 9, 2013
21
CT
Thanks. Can you let me know if your installer used an oval liner or did he just ovalize the 8" round liner to fit thru the damper ?
He just ovalized the round liner. I attached a pic. you can see- the 6” round (outlet of the stove) to oval adapter essentially transitions to a ovalized 8” pipe. if you were to just ovalize 6” pipe you’d create a restriction . you need to upsize it. With my fireplace the its not just the damper- the throat of the fireplace is actually narrow. It’s a true Rumsford with the curved cement leading up to the narrow throat. I didn’t want to start chipping away concrete.

1178CFE6-BA3F-4464-B599-45C680647B18.jpeg
 

stoveliker

Minister of Fire
Nov 17, 2019
6,483
Long Island NY
The point is that any deviation from a circular cross section decreases the cross sectional area(and thus increases the impedance to flow). Hence the need to ovalize a larger circle than the diameter of the flue collar.
 

Jsd245

Member
Dec 9, 2013
21
CT
The point is that any deviation from a circular cross section decreases the cross sectional area(and thus increases the impedance to flow). Hence the need to ovalize a larger circle than the diameter of the flue collar.
Right. You can see they make an adapter just for that purpose which is attached to my stove. So in my case I just used an 8” liner all the way to the top of the chimney Instead of trying to go from 6” round, to 8” oval, back to 6” round at the stove. My chimney is huge- I think 14x14 so there was plenty of room. It’s insulated and there has been no issues for the 7 or so years I’ve been burning with this stove. My chimney is about 26” tall. I’m burning a jotul f55 which has pretty good air control.
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,783
NE Ohio
Just FYI, ovalized liners are a real PITA to clean too...
 

gtandy6

New Member
Oct 20, 2022
9
19348
He just ovalized the round liner. I attached a pic. you can see- the 6” round (outlet of the stove) to oval adapter essentially transitions to a ovalized 8” pipe. if you were to just ovalize 6” pipe you’d create a restriction . you need to upsize it. With my fireplace the its not just the damper- the throat of the fireplace is actually narrow. It’s a true Rumsford with the curved cement leading up to the narrow throat. I didn’t want to start chipping away concrete.

View attachment 302325
Great. Thanks for the picture and detail. Very helpful !!
 
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