Redo of liner: wide difference in liner kit prices--preference? Fabricate an new top cap. And more...

[paredown]

While I'm waiting for parts for the Jotul, and deciding if it goes back in (or we do an insert)--I have been looking at the original job done on our liner, and have decided it needs to be redone.

I need to redo the chimney crown, and fabricate a new terra cotta cap since it is a 20" diameter (!) round flue that the "installers" tried to block off with a simple galvanized disk, hi-temp silicon and a couple of screws (looks like they may have cracked out a small section on the top edge by trying to use screws into the top edge of the terra cotta). Needless to say, it did not stay in place...

Block-off in the fire place is a similar kludge using cement board and furnace cement. (I wish the pictures on hearth.com Block off wiki page were still intact.)

And they used foil tape at the top of the 'T' in the firebox...

Anyways, I've been looking at 6" kits and have been surprised by the range of prices. Any guidance on quality brands (or ones to avoid)?
My install is right around 15' so being able to buy a shorter kit would be nice.)

 

[paredown]

For the top cap--since I cannot find anyone making a terra cotta top cap that is round (or even close to large enough)--here's the tentative solution that I would welcome comments for.

What I can find is a commercial spiral HVAC pipe cap in a 22" size in galvanized (spec says it is 22 ga.). (This will be slightly under size since it fits inside the spiral pipe.)

My thought was to use this to cap the 20" round terra cotta where the sides of the cap will fit over the outside of the terra cotta and give me some overhang. (side will probably need to be trimmed)

What I would then add would be some holes and nuts on the inside edge of the overhang of the cap, so I could add more or less standard bolts to tighten cap to the terra cotta. (Nuts to be JBWelded or--if I can find a guy, tack welded to galvanized.)

Part 2 would be cutting an appropriate center hole for a 6" liner to clear.

Part 3 would be sandwiching (and mechanically fastening) a large top plate with a 6" collar to the galvanized cap. (I have seen a 20" x 20" flat available). I haven't really looked to see if someone could fab up a piece in stainless that would give me full coverage over the galvanized.)

 

[begreen]

A major variant in liners is the thickness of the wall. Liners range from a few steps thicker than foil .005" to significantly thicker .010 or more. There are also construction differences. Avoid the 2-ply liners, despite marketing claims. They tend to have more issues over time. The other option is a rigid liner. This is installed in sections and riveted together. Don't forget the insulation. There are insulation kits that are wrapped around the liner onsite and there are preinsulated liners that have the insulation between an inner and outer stainless layer. Forever Flex is one brand. bholler is our resident expert on these products if you have specific questions.
For a short 15' liner consider a heavy liner. Olympia/Venti Forever Flex is a good one. It is sold under other names like Champion. A couple of good places for liner kits are Rockford Chimney Supply and Woodland Direct.

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[bholler]

For the top cap--since I cannot find anyone making a terra cotta top cap that is round (or even close to large enough)--here's the tentative solution that I would welcome comments for.

What I can find is a commercial spiral HVAC pipe cap in a 22" size in galvanized (spec says it is 22 ga.). (This will be slightly under size since it fits inside the spiral pipe.)
View attachment 296086

My thought was to use this to cap the 20" round terra cotta where the sides of the cap will fit over the outside of the terra cotta and give me some overhang. (side will probably need to be trimmed)

What I would then add would be some holes and nuts on the inside edge of the overhang of the cap, so I could add more or less standard bolts to tighten cap to the terra cotta. (Nuts to be JBWelded or--if I can find a guy, tack welded to galvanized.)

Part 2 would be cutting an appropriate center hole for a 6" liner to clear.

Part 3 would be sandwiching (and mechanically fastening) a large top plate with a 6" collar to the galvanized cap. (I have seen a 20" x 20" flat available). I haven't really looked to see if someone could fab up a piece in stainless that would give me full coverage over the galvanized.)

You don't need a terracotta top plate just silicone a flat one down. But you will need a heavy gauge oversized plate for that. Other than that I agree with everything begreen said

 

[paredown]

You don't need a terracotta top plate just silicone a flat one down. But you will need a heavy gauge oversized plate for that. Other than that I agree with everything begreen said

Thanks for weighing in--I appreciate your (and begreen's) expertise as always.

The problem with the original install--which used a large round galvanized disk siliconed on top of the terra cotta--was that it moved/broke free once we started burning and the liner expanded/contracted (at least I think that is what happened). There is a lot of room for movement in a 20" round tile even with the 8" liner that is currently installed.

Would adding Roxul around the liner keep it from moving as much so the same problem would not recur?

 

[bholler]

Thanks for weighing in--I appreciate your (and begreen's) expertise as always.

The problem with the original install--which used a large round galvanized disk siliconed on top of the terra cotta--was that it moved/broke free once we started burning and the liner expanded/contracted (at least I think that is what happened). There is a lot of room for movement in a 20" round tile even with the 8" liner that is currently installed.

Would adding Roxul around the liner keep it from moving as much so the same problem would not recur?

Just a good solid plate and good silicone set properly will hold up very well.

 

[begreen]

Just a good solid plate and good silicone set properly will hold up very well.

That is how I did ours. Use a generous bead of good silicone adhesive. Ours held so well that even though the top part of the chimney rotated 45º during the last big earthquake, the top plate remained glued. That and the rigid liner saved it from toppling off the roof like our neighbor's did.

 

[bholler]

That is how I did ours. Use a generous bead of good silicone adhesive. Ours held so well that even though the top part of the chimney rotated 45º during the last big earthquake, the top plate remained glued. That and the rigid liner saved it from toppling off the roof like our neighbor's did.

That's how I do all of our liners

 

[paredown]

Is there a special brand or type of silicon you would recommend.

(I see the Rutland ... also Sila Seal Red 600 degree)

 

[begreen]

Get a good brand with strong adhesive properties. It doesn't have to be high heat RTV. I used GE Silicone II.