Running 6" liner, but damper opening just slightly too small

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sr73087

Member
Dec 20, 2016
72
SW CT
So my stove has a 6" collar and the flue itself is plenty big at about 10X10 ID with just under a 24 ft run. However, I measured the opening through my current damper and it is around 5 7/8. What is the proper way to complete this installation?
 
I ovaled my pipe so I could put damper back in if needed and a good thing I did that way cause when we sold the house new owner didn't want stove. Had to pull liner and reassemble the damper
 
You need to remove the damper plate and cut the frame out. Removing a few bricks is also necessary most of the time.
 
I ovaled my pipe so I could put damper back in if needed and a good thing I did that way cause when we sold the house new owner didn't want stove. Had to pull liner and reassemble the damper

I may be in a similar situation. Not sure how long we will be in CT.

What is entailed in "ovaling" the pipe? I know they sell the oval liners. Is this something different?
 
Just had the same situation as you. I used a grinder and cut 9-10 inches width and knocked out some bricks in the back. Helped make the liner almost perfectly straight when dropping in. I left part of the damper up and cut the damper plate with my grinding and put insulation up the vacant hole then put the 2 damper plates back up on each side. This is my block off plate for now till next summer.
 
Yes cut the damper frame. If you do it cleanly and stick the parts you remove up on the smokeshelf it can be put back together
 
And make sure you insulate the liner as well. You have plenty of room
 
So my stove has a 6" collar and the flue itself is plenty big at about 10X10 ID with just under a 24 ft run. However, I measured the opening through my current damper and it is around 5 7/8. What is the proper way to complete this installation?

Reciprocating sawzall will be your friend.
 
I may be in a similar situation. Not sure how long we will be in CT.

What is entailed in "ovaling" the pipe? I know they sell the oval liners. Is this something different?

I had a similar situation. Measure the distance between the top of the liner "T" connector and the damper opening, then compress the leading end of the liner, making it oval shaped, before pulling it down the chimney through the damper opening. Then round out the end of the liner to fit on the "T". It doesn't harm the liner. I definitely would not cut the damper, or remove any bricks.
 
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Ovalizing the liner can absolutly make weak points in the liner if it kinks when you smash it. It also hurts draft and makes it harder to clean. Cutting the damper frame which is usually enough only takes a couple mins and it gives you better access to make sure that smoke chamber and shelf is clean. And like i said if you stick the peice on the smoke shelf it can be put back in place with a couple scraps of plate steel and bolts. The benifits of keeping the liner round greatly out weight the downsides to cutting the frame. Even if you have to pull a brick or two they can easily be put back.
 
When you look at lightwall ss liners ( the ones most commonly used), it’s amazing how thin they are for having such a big job to do. Any unnecessary ovalizing and squishing seems like a bad idea and avoidable by using the guidance by bholler above.
 
Ovalizing the liner can absolutly make weak points in the liner if it kinks when you smash it. It also hurts draft and makes it harder to clean.

I can't dispute what you're saying, because you have a lot more experience than me. However, I actually tried cutting the damper frame with a carbide sawzall, and couldn't make a dent. I compressed the liner gently with a length of 2x12 down to 5" without causing a kink. It was more difficult rounding it out than compressing it. I bought an extra fiber brush, cut 1/2" off opposite sides, to fit through the oval section. It's barely 2' from the liner "T" clean-out cap through the oval section, and I brush that frequently from inside. It's worked out well for me.
 
I can't dispute what you're saying, because you have a lot more experience than me. However, I actually tried cutting the damper frame with a carbide sawzall, and couldn't make a dent. I compressed the liner gently with a length of 2x12 down to 5" without causing a kink. It was more difficult rounding it out than compressing it. I bought an extra fiber brush, cut 1/2" off opposite sides, to fit through the oval section. It's barely 2' from the liner "T" clean-out cap through the oval section, and I brush that frequently from inside. It's worked out well for me.
Well the sawzall is the problem. It is a pita to do that way. An angle grinder will slice right through it. And it can work just fine being ovalized through the damper. But there is much more potential for problems doing it that way.
 
Just throwing another idea out there. Is it out of the question to run a 5.5" liner and it should fit without issues?
It will still be really tight. It is 5.5 inside easily 5.75 outside you want a little room.
 
It will still be really tight. It is 5.5 inside easily 5.75 outside you want a little room.

Thanks for all the info. I think I would rather it fit with a 1/10” clearance than create a big job or ovalize it. The main concern is if it’s big enough. Does the 5.5” have enough volume for a 6 inch stove? Or is this the normal application for running 5.5? Not sure if many stoves came in 5.5”.
 
Thanks for all the info. I think I would rather it fit with a 1/10” clearance than create a big job or ovalize it. The main concern is if it’s big enough. Does the 5.5” have enough volume for a 6 inch stove? Or is this the normal application for running 5.5? Not sure if many stoves came in 5.5”.
If you had ever tried to get a liner through a damper and hooked to an insert you would know 1/10" is nowhere near enough. It may be possible but it is much easier to just do it right and cut the damper frame out. It really is at most a 5 min job with a grinder. People like me that do it all the time it is a min or 2.