11785 Insulated chimneys

We are just about to construct our internal chimney flues and I am looking at methods for insulating them. One, I know is the double skin stainless steel solution, but in a room that has a very high ceiling (the roof in fact) this could prove very costly and would leave us wondering what to do with the base of the chimney stack, which is visible within the room. We could simply extend the stack downwards with what's already there, namely square concrete modules with stainless steel linings. The trouble is, these have less than 25mm of mineral wool between steel and concrete, which looks more like allowance for expansion than whole hearted insulation to me. In England the solution would be easy: Isokern pumice liners and mica insulation poured into the outer casework around these and this creates a chimney with truly exceptional characteristics, but Schiedel Isokern don't market these products in Italy. Perhaps, I'm underestimating the concrete and stainless product; perhaps there are some advantages to double skin stainless - e.g. more heat into the room?
Anyone able to advise? (especially anyone who has been able to source mica and liners for insulation in the way that I described!)

Category
Building/Renovation

Submitted by Anonymous (not verified) on Sun, 03/01/2009 - 03:39

Do you mind if I piggy-back my question onto your thread instead of starting a new one? My problem is that the main chimney here in a 1980s house has been constructed solely with concrete blocks - no stainless steel liner, let alone any insulation. The consequences being that the room initially fills with smoke until the draught gets going and once the fire is roaring the concrete chimney and plaster covering in the room above has started to crack (inevitably). I've no idea whether it is a 'take it all down and start again' job, or if it's 'take the chimney off and insert the liner down the chimney'. Local builders haven't been any use. If you find an expert to advise you on your problem perhaps they can suggest how on earth to deal with mine!
Thanks!

Submitted by Anonymous (not verified) on Sun, 03/01/2009 - 04:15

Jump on certainly! All I can say is that lining and insulating will have a big impact on the initial draw. We were able to run an open fire with just a 200 mm flue, simply because it was highly insulated - and the chimney sweep visited once in 12 years and said that there was nothing for him to clean.

Submitted by Anonymous (not verified) on Tue, 03/03/2009 - 01:37

Hi Barn-Elms, If you're still reading this thread, there are two websites that might be useful to you. [url=http://www.expoinox.com]EXPO INOX s.p.a. -- canne fumarie, cancelli, recinzioni, pavimentazioni, parapetti, arredo urbano[/url] has the big advantage of English and Italian versions of their pages, as well as lots of diagrams and specs for just about every kind of material and design relating to stainless steel chimney liners that you could wish for. The other more homely site is stoves on line (sorry, you'll have to google it) which has pages of advice on lining chimneys. Obviously, both theses sites are rather more oriented to stoves than open fires, but you can extrapolate ... or you might even consider installing a stove as part of your solution. Anyway, I went to my nearest builders yard with some pages from Expo Inox and now we have a really good design which isn't going to cost the earth either,

Submitted by Anonymous (not verified) on Tue, 03/03/2009 - 07:13

[FONT="Comic Sans MS"]We have just gone through the 'chimney problem' phase. We had a new stufa fitted by a local builder about three years ago. He fitted the standard brown flue pipe through 2 floors (about 5 metres) and out through the roof. Worked fine initially but got more and more smokey despite all cleaning attempts. In the end was virually unusable. A local German builder came in and has built a concrete and plastered chimney and it is fine again. When he came to do the work, he discovered that condensation had run down the tube bringing all the soot with it turning it into a horrible black tar and completely blocked the bottom metre of the flue. The rest of the flue pipe was about half the diameter is should have been. I will ask him what the new chimney is lined with. The other problem that he identified was the extension of the chimney above the roofline was not enough. [/FONT]

Submitted by Anonymous (not verified) on Tue, 03/03/2009 - 08:33

There does seem to be a lack of understanding about the physics involved in successful chimneys. Surprising really for a people who depend so heavily on stufas. I've had more arguments with my geometra about chimneys than anything else. We've finally got ours extended (and insulated) to "above roof line", though i'm yet to be convinced that it is high enough.

Submitted by Anonymous (not verified) on Mon, 03/09/2009 - 07:47

check [url=http://www.extraflame.it/support/]Extraflame SUPPORT - Home[/url] for detailed drawings on how to line a chimney!

Submitted by Anonymous (not verified) on Mon, 03/09/2009 - 19:27

Paola, are all your houses sideways on :)

Submitted by Anonymous (not verified) on Tue, 03/10/2009 - 04:08

[quote=Skichi;113205]Paola, are all your houses sideways on :)[/quote]

Well - after all, he is an Architect

.

Submitted by Anonymous (not verified) on Tue, 03/10/2009 - 05:27

I am a woman and an architect...what a combo!

Submitted by Anonymous (not verified) on Tue, 03/10/2009 - 07:52

" he discovered that condensation had run down the tube bringing all the soot with it turning it into a horrible black tar and completely blocked the bottom metre of the flue".
My woodburning cooker was producing more and more smoke last week. I took my flue pipe off and found it blocked with sooty tar stuff. After a good clean, it's now perfect. I'll have to remember to clean it once a year.