Can I line an 8" chimeny with a 6" liner

[HeatMaster]

I am new to this forum, however, have been browsing for a few weeks now. All these good topics have generated a few questions within my mind . Let me continue with the second one. I'll post the others in dedicated topics.

I have a double wall 8" stainless steel chimney pipe that used to be for my fireplace insert. The wood stove I am getting comes with a 6" flue. I read that it is not recommended that I use anything but a 6" chimney. Can I pull a 6" SS flexable liner into the 8" pipe? If so how is the maintance with flex liners? Does creosote trap more easily in the joints of the flex pipe?

thanks

 

[offroadaudio]

Just make sure the manufacture of the 6" does not require a certain clearance around the liner for heat dissipation.
My guess is that you will be fine, maybe even well off with the extra protection? Assuming it's ok per the manufacture, I'd try to find spacers to center it in the 8".
The flex liners are the same to clean as long as you go by the golden rule: burned seasoned wood.
If you burn hot and use good fuel, you'll only get a few cups of flakes each season.

 

[jtp10181]

8" double wall... is this a Class A HT system or just an Air Cooled? You said you have an insert now? I have never seen an insert that uses a double wall, or maybe you have a built in ZC unit and you are going to tear it out?

If you have a UL listed 103HT Class A system right now that is 8" you could simple pull a 6" liner down it no problem and you would be fine.

IF you have an air cooled prefab chimney system then you need to fully insulate the liner from top to bottom so that it meets the UL 1777 listing. You can still get that down as it ends up being about 7.5" OD, but its is a VERY tight fit. You also need to make sure the air cooling chamber remains in tact and able to breathe. If you tear out the wood unit attached to this chimney system, that compromises it and it also must be removed.

 

[wahoowad]

I always wonder how these flexible liners behave when it comes time to ram a cleaning brush up and down it's gullet. I picture a liner being secured at the top and bottom but somewhat flexible in the middle. A round wire or plastic brush on a flexible extension pole just seems like it would be difficult to get an up and down scrubbing motion with the middle portion moving around. I currently push down agains tthe resistance of my rigid chimney to get the brush down, then pull up against the resistance of the rigid chimney to get the brush to move up.

 

[HeatMaster]

Well I did some research on this last night. I currently have a B-vent air cooled chimney. I cannot pull a liner into it, it won't meet code. I will have to replace it with a proper chimney flue (UL 103).

 

[jtp10181]

B-Vent is for gas appliances only and is not air cooled... it is double wall but usually only a small stagnant air chamber which makes it "air insulated"

 

[HeatMaster]

yep, you are right it is double walled with an air gap. Too bad I cannot reuse it, it is a nice stainless steel inner pipe.