Chimney or chimney liner noise ?

[henryohenry]

Hello,

Forgive this rambling question, I seem to need to give so much info to avoid confusion.

Last year I had a chimney and liner fitted for my new wood stove.

The liner is held in by a cowl that straps to the chimney pot and to the top of the liner.

I began to noticed a slight knocking that occurred during windy weather, that has over the last year become louder and louder and more frequent; to the point where my neighbour commented and to the point where during the last bout of weather it became ridiculously frequent and chaotic.
I am not sleeping well.

It is heard most loudly in the wall in the bedroom but can be heard from downstairs also.
If I put my ear to the liner I can hear it but not to the extent that I would imagine if it was the actual liner moving.

It is a thumping with some weight behind it.

Imagine dropping a tennis ball from exactly three inches high onto a concrete floor. Dum,dum,....dum,.......... dum.

I don't know if it is it more likely to be the liner or the chimney or anything else that anyone has experienced.

Has anyone on on this site experienced chimney liner thump; I have searched and cannot find any information on it, it seems so inflexible and heavy that I can't imagine it.

I removed the stove and pulled the liner down as much as I could , gaining only about 2", is it possible that it could be knocking insde, even when it is this taught? It made no difference.

Is it possible for a chimney itself to rock with the noise that I have described ? I would think that something that heavy would rock very slowly ?

The background to all this is; the winter before we could hear knocking during extremely windy weather but to nothing like the extent of the present.

The builder said the chimneys up there were a bit dodgy and could do with repointing.

The original chimneys were in a grouping of 8 but after renovating, only the outer 6 were replaced. The builder had to reopen the inner flue for my front room and put on a chimney pot .

Could this have helped weaken the chimneys?

I have stared for hours at my chimneys through binoculars and cannot see any movement. I can see cracks in the outer chimney flaunching though.
Another chimney on this street needed chimney work recently, although this was an end terrace, ( 3 storey, not 2, like mine ).

Well, if you got to this point, well done.

Any advice?

Thank you for your time.

Henry.



Extra facts:
It is proper double walled stainless steel liner.
The liner is not insulated; we read that it was not necessary in this instance.

 

[oilman]

It might feel stiff, but you need surprisingly small amount of power to make something resonate. Changing the cowl to something better designed may fix it, and stuffing some wads of insulation up or down the chimney may help.

 

[henryohenry]

Dear Oilman,

Thanks for your reply.

I'm going to try pushing insulation ( rockwool ? ) up around the liner with a chimney rod set and hope that will help.

Do you actually know of this thumping happening to someone with a liner ?

Thank you

Henry.

 

[iangrant]

I apologise for bumping a very old thread, but I've searched and searched and this is the only place where I've heard the same problem that we're experiencing described: the sound is exactly that, a tennis ball being dropped from a small height. On the off-chance that you're still around...Henry, did you ever manage to resolve it?

 

[snes]

Our Hetas boys should be able to help on this a bit later, but as a quick response - and I'm not Hetas - shouldn't insulating material (eg vermiculite) have been dropped down the chimney flue, thus insulating (and stabilising) your liner?

What a horrible, long, sentence! Sorry about that, hope it makes sense.

 

[muggles]

It's advisable on long flue run @snes but most two-storey houses wouldn't need it. Having said that, it would stop the liner moving if that is what's causing the noise - cheap low-grade liners can be quite flexible so it wouldn't take much for them to move. Could be that the hanging cowl has come a bit loose...

 

[iangrant]

Thanks very much indeed for your replies. Much appreciated.

It sounds like something lifting and dropping - hence the tennis ball comparison - rather than a rattle, if that's any use. It's a very consistent sound: it's an old house on a hill, so there are lots of rattles when it gets windy, but this is as if something's being picked up by the wind and then falling back down again.

It's a three-storey chimney, so not easy to get up there for a look. There's nothing obvious from ground level, even if you look through binoculars.

If the advice is to get a pro to look at it, that's fine. It just feels like a bit of a wild goose chase at the moment, particularly given how inaccessible it is.

Many thanks again.