5.5" insulated vs 6" Chimney Liner - any first hand experience?

[Sixwaypwrmudflap]

Greetings Hearth forum. I have been visiting this site for the past few years in preparation for a fireplace insert install. I was finally able to pull the trigger on a CW2500 insert that I picked up used locally. The owners manual calls for 6" chimney liner. I would like to install pre-insulated stainless steel liner due to the fact that my chimney is located on the east side of my house and exposed to the elements. However, with the 8x13 clay flue the actual inside dimension is ~6.75" and the insulated 6" liner is ~7.25" . I can fit a 5.5" pre-insulated liner, but I concerned about the performance of the smaller flue. Anyone out there have any experience running 5.5" vs 6"? Any notable changes?

I should also mention that my chimney is ~23' -11", and constructed of 8x13 clay flue liner and 21x8x16 chimney blocks.

 

[bholler]

I concerned about the performance of the smaller flue. Anyone out there have any experience running 5.5" vs 6"? Any notable changes?

Ask the stove manufacturer about it.

I can fit a 5.5" pre-insulated liner

Are you sure about that? it may fit in the first liner but what happens when one of the joints is misaligned even a tiny bit? I seriously doubt it will fit I would say you either need an ovalized liner or you need to remove the old clay tiles.

 

[Sixwaypwrmudflap]

I have submitted this question to Century Heating, but have not heard a reply back.

 

[fire_man]

I had the exact same issue and ended up ovalizing.
You don't want to order a liner that ends up not fitting or damaging it while trying to jamb it in.

 

[bholler]

You don't want to order a liner that ends up not fitting or damaging it while trying to jamb it in.

Or worse yet getting it stuck in the chimney part way down. That is really a kick in the nuts when that happens.

 

[jatoxico]

That is really a kick in the nuts when that happens.

LOL that struck me funny! Carry on.

 

[Sixwaypwrmudflap]

My gut tells me with that with nearly 24' of stack height, the difference in insulated vs. non-insulated, and 5.5" vs. 6" is inconsequential. With the height of the chimney I should get great draft.

But my brain tells me to never trust my gut!

 

[fire_man]

I ovalized a 6" liner which definitely reduced the surface area but it drafts like a crazy since it's 24+ feet tall (like yours).

 

[rdust]

27' of 5.5 liner with pour in insulation, with about 3' of double wall. Has drafted fine with my current BK and Lopi non cat. Was actually too much for the Lopi.

 

[bholler]

insulated vs. non-insulated, and 5.5" vs. 6"

insulated or non insulated will absolutely make a huge difference in performance and safety

I ovalized a 6" liner which definitely reduced the surface area but it drafts like a crazy since it's 24+ feet tall (like yours).

Yeah over 20 fett you can usually get away with 5.5 or an ovalized 6" but you should always check with the stove manufacturer.

27' of 5.5 liner with pour in insulation,

In his case there will not be enough room to properly insulate with pour in.

 

[Sixwaypwrmudflap]

27' of 5.5 liner with pour in insulation, with about 3' of double wall. Has drafted fine with my current BK and Lopi non cat. Was actually too much for the Lopi.

rdust, this what I am leaning toward. Where did you source your pour in from?

 

[Sixwaypwrmudflap]

In his case there will not be enough room to properly insulate with pour in.[/QUOTE]

Can you elaborate on this? I am thinking with a 5.5" liner I will have an actual diameter of 5.75", the narrowest actual dimension of the flue tile is 6.75" this would gave a minimum insulation of thickness of a half inch. The pre-insulated liners offer a 1/2" thickness. Is there something that I am overlooking that is needed for pour in insulation?

Thanks for all of the replies! It is really appreciated!

 

[bholler]

Is there something that I am overlooking that is needed for pour in insulation?

yes 1" of insulation not 1/2" with the pour in. Wrap only needs to be 1/2"

 

[edthesweep]

Is there something that I am overlooking that is needed for pour in insulation?

Also I doubt you could keep the liner centered and not up against the tile flue in at least one or two spots

 

[bholler]

Also I doubt you could keep the liner centered and not up against the tile flue in at least one or two spots

Absolutely we use pour in quite a bit but mainly only on oil or gas furnace liners where the insulation is just to help control condensation and stabilize draft. It is not a safety issue