Can I install a class-A metal chimney into an old masony chimney, using it as a chase?

[nscarnati]

I have an old (1880) house with a 24' tall masonry chimney. I have been looking into relining, first I wanted to do a rigid metal liner, but with missing mortar in the joints, I was concerned about the heat transfer to combutibles on the other side of the brick. Then I figured I'd try to splurge on a cast-in-place liner if I can afford it, but can't find a single dealer in the area (I called the manufacturers to get references of local installers - both supaflu and golden flu - no luck).

So now my idea is to install 6" (interior dim.) Class-A chimney pipe (simpson duratech or duraplus) inside the existing masonry chimney (which is 18x18 interior dimentions, straight shot vertically from fireplace to crown, so I shouldn't have any clearance issues), effectively using the existing chimney as a chase. Is this safe and legal to do, and has anyone ever done anything like this before? I figure there should be almost no heat transfer from the class-a chimney to the brick chimney, and if there is it should be far less than if I were to use rigid meta liner instead. After all it's made to pass through wood framed ceilings/walls safely.

Any thoughts? I need to get this done soon, so that I can use my new Jotul F100 before the seasons over!

 

[Pagey]

I'm no expert here, but I'm guessing assembly would be a problem. Most of the Class A I've seen comes in, say, 3' sections that twist lock together then fasten with a band for additional support. I suppose one could try to assemble 24' worth and maneuver them around, but I imagine the weight would be tremendous.

 

[pyro68]

It can be done, rather difficult if you need to go around any bends or offsets. HT aircooled pipe would be lighter. Pipe would have to be pushed up from the bottom, assembling as you go, or dropped down from he top. I'd recommend that single wall flex liner w/insulation wrap around it. No need to worry about the chimney and much easier to do.

 

[pyro68]

sorry, missed the part about wanting the ridgid metal liner, that could be used with the insulation wrap as well.

 

[Dave_1]

What size opening is your fireplace?

As Pagey noted weight & clamping may be your problem.

Can it be done? Depends on your strength, helpers strength, & size of the fireplace opening.

According to

(broken link removed)

Assuming that you can get a 3' piece into the fireplace opening & banded it will weigh 10 lbs a section.

So you would need 8 sections or 80 lbs of pipe.

But 80 lbs becomes a ton when a person is confined & forced to use arm strength alone.