On 24/12/2020 11:52, Tim Lamb wrote:
In message , writes
On 24/12/2020 10:55, Tim Lamb wrote:
In message , alan_m
writes
On 23/12/2020 11:48, wrote:

Thanks, but I'd ruled-out a DIY version of those because of the
problemsÂ* of storing a big sooty thing, and crud falling down when
it's pulledÂ* from the chimney

Irrespective of any mode of blocking you are going to get the crud
that has fallen on the blocking mechanism dropping down when opening
up again, otherwise where do you expect this crud to disappear to?

Even with a bespoke fixed design consider how it is to be cleaned.
Â*I think they centre pivot so the crud slides off when opened.
Â*The fixing trick is knowing that you have to take out and replace
someÂ* brick above your fire opening.

No, it would be fixable from inside the chimney and have minimal
effect on the throat when open

Hmm. I have done a couple. Both times the best access was through the
front of the chimney.

OK. I'm going mostly by this chap:
https://www.chimneydampers.co.uk/fireplace-dampers (and the fact that we
have a large stone fire surround that I do not intend to disturb). The
fire opening is over 1m wide and nearly a metre high, reducing to a
good-size square flue - there seem to be several fixing good
opportunities for fixing points.