Lining chimney

[patchallboys]

I live in a 150 year old cottage. We have been there a year and when we moved in it had a living flame gas fire installed. We wanted a wood burning stove to be installed. I had the gas fire removed and are now ready to have the stove installed.

The chimney has a liner suitable for a gas fire, which only seems to be lined about two thirds of the way? (I have been repointing the chimney breast in the attic and the mortar is very crumbly and has been coming down the liner into the fireplace downstairs)

Another worry is that the inside of the chimney seems to be very crumbly. I very much doubt that the chimney can be used without relining, and would very much appreciate any advise on how this can be done – what exactly needs to be done?

Many thanks

 

[Shytalkz]

Insides of old unlined stacks do get crumbly, as the exhaust gases react with the old mortar; and the heat cracks the bricks as well. Often, a stack can look seemingly ok on the outside, but, for a multi-flue stack, the whiffs (separating bits between the flues) may be shot to pieces. Bits dropping down into the fireplace is often a sign that all is not well...

It certainly needs lining all the way from top to bottom. There are specialist flue lining companies who know a great deal more than I do about this sort of thing and it would be worth you getting one or more of them to have a look. A good one will do a camera survey.

The installation will comprise the insertion of a flexible liner, relevant to the type of appliance, which they then line around with vermiculite.

 

[Joe Malone]

There is also another way. Specialist companies will inflate a balloon liner down the full length of the chimney. They'll then pour a lightweight concrete mix down around the balloon. When this sets, the balloon is deflated then removed and you're left with a perfectly formed lining that should last longer than the original. Once the pargetting has gone inside the old flue theres nothing you can do to repair it.

 

[Shytalkz]

Is that ok for a gas appliance, though?

 

[Shytalkz]

Uh duh, he had gas, now he's putting a woodburner in, sorry

 

[Joe Malone]

No, it's a good point though. I'm sure it is so long as the throating arrangement complies with CORGI regs.

 

[Shytalkz]

Mind you, I was under the impression that, with enclosed woodburners, the temperatures up the flue are humongous, particularly the fan-assisted ones, so would the ballon type be ok for that?

 

[Joe Malone]

Especially so, you're effectively left with a concrete cylinder so the heat resistance is about as good as you can get.

 

[Shytalkz]

Hah, never thought of that! Call myself an engineer??!