Liner and cap on a 100 year old Chimney with rectangular flue

Stickley · Apr 10, 2019

I need some advice getting my chimney lined and capped. Per my thread on choosing a stove, I plan on having Jotul F45 or Hearthstone Craftsbury professionally installed by the dealer. However the chimney needs to have the top courses reset, and the dealer is not a mason, so I need to solve that first.

The chimney is 100 years old, and inside the house. It is clay lined and appears to be in good shape. 2 Flues (the second is unused and goes into basement)
The stoves require a 6" liner, and the flue inner dimensions are 7" x 15".
The mason is going to rework the firebox to raise the lintel and open the smoke shelf gap for the liner, and fix the chimney top and cap it. He offered to install the liner, and I think I'd prefer so he can make sure everything is ready to go when the stove arrives.

I'd like to be an educated consumer as many contractors *cough*HVAC*cough* sell bottom of the barrel equipment for top dollar.

Do I need an insulated liner?

Should I use an oval rectangular liner? I have talked to 3 sweeps they mention they can "ovalize" a 6" liner, effectively by stepping on it. Seems like ordering the correct part would be a better plan. If so, what size oval / square meets 6" round?

I was planning on a new stainless multi-flue cap and flex liner because it looks like there is an offset at the bottom.

One person I talked to said something along the lines of "because your old chimney is internal to the house, and does not have 2" spacing to combustibles, to meet code I would have to pour some loose cement inside the chimney to provide another barrier between the metal liner and the clay liner". I think this is a "cast in place" liner? That doesn't seem right for a chimney with steel liner + clay liner already in place.

bholler · Apr 10, 2019

Yes you need an insulated liner. No you should not hire any of the guys who said they would ovalize it by stepping on it. They should either have an ovalizer to do it properly or order oval. No you shouldn't use pour in it doesn't work well in a fireplace and you won't get the required 1 inch of insulation surrounding the liner. It should be wrapped on site or pre insulated.

double-d · Apr 11, 2019

Your are probability looking at a 5" x 8.15", or 4.5" x 9.1" Oval liner, these would fit with the 1" insulation blanket on them. There are also some Rectangle sizes than would fit, 4.5" x 6.5", or 5" x 7", neither the oval, or rectangle liner, has much flexibility to them, so if you do have an off set, it may not make the turn, especially with the insulation.
The chimneys I've seen, with 2 flues, it's usually the one going to the basement that has the offset, not the one upstairs, but you will probably have a little offset going through the smoke chamber and damper area.

If the chimney clay liners could be broken out, you might be able to just use an insulated 6" Round Liner.

A multi flue cap may or may not be the best answer, if you don't close off the second flue going to the basement, the exhaust from your stove, may get pulled right back down into the basement, and fill the house with smoke.

bholler · Apr 11, 2019

double-d said:
Your are probability looking at a 5" x 8.15", or 4.5" x 9.1" Oval liner, these would fit with the 1" insulation blanket on them. There are also some Rectangle sizes than would fit, 4.5" x 6.5", or 5" x 7", neither the oval, or rectangle liner, has much flexibility to them, so if you do have an off set, it may not make the turn, especially with the insulation.
The chimneys I've seen, with 2 flues, it's usually the one going to the basement that has the offset, not the one upstairs, but you will probably have a little offset going through the smoke chamber and damper area.

If the chimney clay liners could be broken out, you might be able to just use an insulated 6" Round Liner.

A multi flue cap may or may not be the best answer, if you don't close off the second flue going to the basement, the exhaust from your stove, may get pulled right back down into the basement, and fill the house with smoke.

Heavy wall still flexes fine ovalized. And you only need 1/2" blanket wrap. 1" for pour in.

Ctwoodtick · Apr 11, 2019

Unless I missed it above, your clay liners looked like they’re covered in glazed creosote which is a big safety issue. Maybe choose to have them broken out and then install insulated liner. Definitely don’t install a liner into those clay tiles the way it is now. Nor would I use the fireplace with that sort of buildup. If any of the people you have looking at that didn’t bring that up to you, I’d lose their phone number fast.

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Liner and cap on a 100 year old Chimney with rectangular flue

Stickley

New Member

bholler

Chimney sweep

double-d

Feeling the Heat

bholler

Chimney sweep

Ctwoodtick

Minister of Fire

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