Decommissioning a Chimney Liner

30 Jul 2018
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United Kingdom
Just had an oil-fired boiler removed which was served by a stainless flue liner running up through a brick chimney which won't be used again. There's currently no chimney ventilation apart from the liner itself which is still open at the cowl. The liner at the bottom is actually mortared around its exit from the chimney. I can only guess that the air space between the inside brick of the chimney and the outside of the liner is unventilated but there's no chimney damp probably due to the liner heating up regularly. However, now the boiler's gone I'm guessing damp might become a problem unless I ventilate the chimney. The chimney runs up through the middle of the house, so only exposed to weather above the roof.

I guess the gold standard would be to remove the stack to beneath the roof line and leave it open, but I'm looking for a quicker and cheaper solution. I'd appreciate some advice please. My thinking is:

1. Puncture the liner where it enters the house on the ground floor. This will create an air flow between the liner and the inner chimney. I just hope it's not full of beads. I'd fit a plastic vent over the liner entry point (which is at the back of the disused boiler cupboard, so no issue).
2. Knock out a brick in the chimney within the loft space (not above the roof) and replace with an air brick.
3. Seal up the cowl above the roof.

This would be cheap as chips and within my DIY comfort zone, but would this cause problems I haven't yet thought of? Should I expect condensation inside of the liner too?

Any help or advice would be appreciated.

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quickest an cheapest is for someone to go on roof an pull the liner from the flue after releasing it in the fireplace. then sweep the flue.make good any flaunching or ventilation terminal.
EnemyXMusic, good evening.

I saw a situation up here a couple of weeks back where the flue liner was installed in a very large detached stone built property, on the gable the sandstone at the top of the chimney flue had disintegrated due to Sulphate attack within the now un-vented flue, un-vented because of the sealed top and bottom liner that had been installed.

Unfortunately Sulphate attack is not covered by any insurance policy, so the cost of repair would fall to the owner.

There may be some mileage in working from the outside, in that if you locate and install two air bricks to the external walls, you will lessen the disruption internally, fit one air brick as close to the top of the flue as possible and the other behind the fireplace or in your case the boiler cupboard.

One problem that you may encounter if you make a hole in the flue and remove is that there may be an on-going smell of burned flue gas that could get into the old boiler room? from residual burned materials adhering to the flue.

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i read the above reply last night and wondered what you were talkin about but thought lets sleep on it.
i just read it again an its still doesnt make sense.

the chimney is in the middle of the house, so why install air bricks on outside walls?
lessen what disruption internally ?
youve just installed four air bricks by my count. that sounds like possble disruption.
installing a air brick directly behind the fireplace could be well dangerous if the next house ocupents go for a solid fuel fire.just because the OP suggests somethin doesnt make it right.

thers no need for any airbricks at all.
,just through ventin from fireplace to terminal will vent the flue.
but how is an airbrick in a cupboard goin to supply fresh air to the flue?
youd have to vent the cupboard itself.

the OPs proposals wont fly,ianswered his question,ifhe wanted anymore advice all he had todo was ask.

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