Fri, 29 May 2026 22:32:35 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38185#Comment_38185 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38185#Comment_38185 Thu, 13 Nov 2008 22:31:58 +0000 neelpeel He also said that Hetas doesn't recommend insulating in their latest literature.

The chimney is made of thick stone and is in the middle of the house (i.e. not on outside wall) so I guess there should be less chance of moisture.
Also, its quite a large chimney so filling wouldn't be my first choice.

Should I get away without insulating?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38188#Comment_38188 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38188#Comment_38188 Thu, 13 Nov 2008 23:37:49 +0000 Dan McNeil
Don't cheapskate.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38189#Comment_38189 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38189#Comment_38189 Thu, 13 Nov 2008 23:42:31 +0000 wookey
A large chimney means it's more likely to need lining than if it was a small chimney, but there is no reason not to suck it and see. If it draws OK, and you don't get excessive deposits after 1st year then that's fine. You can always line it later if you like.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38191#Comment_38191 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38191#Comment_38191 Thu, 13 Nov 2008 23:48:19 +0000 Dan McNeil https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38208#Comment_38208 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38208#Comment_38208 Fri, 14 Nov 2008 09:46:21 +0000 owlman https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38227#Comment_38227 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38227#Comment_38227 Fri, 14 Nov 2008 12:22:24 +0000 neelpeel He's done dozens of installs and has never had an issue with not insulating.

I'm actually a bit confused about this. If I insulate does it not mean that more of the heat is going straight out the chimney. As the chimney is internal, will I not get the benefit from whatever heat goes into/through the chimney stack and back into the house?

I could understand a case for insulating the bottom 200mm or so to stop heat loss into the chimney from the register plate. Would this make sense?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38229#Comment_38229 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38229#Comment_38229 Fri, 14 Nov 2008 12:54:00 +0000 owlman https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38230#Comment_38230 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38230#Comment_38230 Fri, 14 Nov 2008 12:54:57 +0000 neelpeel https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38236#Comment_38236 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38236#Comment_38236 Fri, 14 Nov 2008 13:16:56 +0000 Johnh
As an alternative, if your chimney tapers as it rises, wrap the lower section in Rockwool and form a bung with the same material at a point where the flue narrows. Fill the remaining area from the top with vermiculite. We paid around £13 for a large bag a month ago from our local builders merchant.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38241#Comment_38241 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38241#Comment_38241 Fri, 14 Nov 2008 13:47:11 +0000 billt https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38259#Comment_38259 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38259#Comment_38259 Fri, 14 Nov 2008 18:00:01 +0000 owlman For neelpeel; you say your man is insisting on an air vent, presumably to increase draught. If it's an inside chimney where is the air coming from? Is it directly from outside, or is it the centrally heated air from within the house thats been sucked up the flue?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38260#Comment_38260 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38260#Comment_38260 Fri, 14 Nov 2008 18:50:52 +0000 CWatters http://www.stovesonline.co.uk/wood_burning_stoves/Flexible-Flue-Liners.html

Quote: Insulating flexible flue liners in wide chimneys has always been a problem because of the large amount of leca needed to backfill the chimney. Now we carry rockwool sleeves, by Rocklap, that just clip around the liner as it goes down the chimney. The rockwool sleeves are strong lengths of pre-formed insulation with a one piece, factory applied foil facing with an integral self-adhesive lap.

I've no idea if it's any good. I'd be tempted to put more tape around the outside or perhap some stainless steel wire ties.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38262#Comment_38262 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38262#Comment_38262 Fri, 14 Nov 2008 20:11:35 +0000 JSD https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38272#Comment_38272 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=38272#Comment_38272 Fri, 14 Nov 2008 21:38:43 +0000 Johnh
The SS liner with vermiculite insulation is the best performer - far less soot/deposits and better draw.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=85975#Comment_85975 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=85975#Comment_85975 Mon, 26 Jul 2010 16:05:21 +0100 fidhw We are planning to line 2 chimneys with 316 ss flexible liner. Chimney 1: daily winter use, 22kw wood stove heating water (needs good draught); 7m straight up-and-down chimney topped with Windkat (helped but not enough) and sealed to the stovepipe at the bottom via concrete register plate (not our doing). We suspect the large chimney volume slows the draw (16 inch square chimney built c.1900). Chimney 2 is much more difficult: irregular use of a 16kw woodstove for bitter winters and visiting wusses. Total chimney length 10m but almost 3m of that is near-horizontal (older than 1900) ending in a huge inglenook. We are hoping the liner will take advantage of the wide chimney and effectively 'remove' some of this horizontal (but rebuilding the chimney is not an option).
So, please help me de-confuse:
1. Air is a good insulator (if it doesn't escape/move). If the chimney space is sealed top and bottom to the liner, do we have to add other insulation? Chimney 2 is certainly not going to be possible to fit liner blanket in...
2. If we have to insulate, is LECA or vermiculite going to be better at making its way down a kinky chimney around the liner? The walls are stone and breathable, so we can't rule out damp (feels dry up there though, and I've been up Chimney 2 as far as the serious kink). Which insulates better?
3. How do we work out how much (insulating stuff) to order, and where do we get industrial quantities of e.g. LECA (North Wales)?

Many thanks all, and I apologise if this seems to be a repeat of earlier discussions but there seem to be many conflicting opinions (including those of professionals I've asked). I don't even want to think about getting tons of filler material onto the house roof...
Rachel]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=85997#Comment_85997 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=85997#Comment_85997 Tue, 27 Jul 2010 09:02:35 +0100 finny
improve draw, speed up the lighting process and help achieve the burn phase much quicker, saving you time and wood.
prolong the life of your stove and the stainless steel liner.
reduce heat losses from the building 24 hours a day whether the stove is lit or not.
In extreme circumstances it could save your life as your noxious gases are less likely to fall back down the flue after the burn phases.

As for problems getting back to the liner in future..start the pour with a mix of vermiculite and lime or cement to create a plug at the bottom. dry vermiculite, then another mix at the top to plug and bond before the pots go on..

Our (Mid Wales) chimney breasts are 10 metres, one with originally 5 flues, the other with 4. The vermiculite at just over a tenner per 100 litre bag from any builders merchants amounts to around 500 quid on this big building with 4 stoves, one rayburn and a log boiler. Most chimney breasts would not take more than 1000 litres=100 pound or so..]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=86175#Comment_86175 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=86175#Comment_86175 Fri, 30 Jul 2010 11:00:08 +0100 owlman https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=86184#Comment_86184 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2937&Focus=86184#Comment_86184 Fri, 30 Jul 2010 13:46:52 +0100 crusoe
A few observations: On occasions, as somebody pointed out above, a warm, dry (pref lime mortar constructed) chimney with a correctly used stove, sans lining, will deteriorate at a negligible rate (all chimneys deteriorate, btw, even volcanic pumice, it's just a matter of time and chemistry...), especially a warm, internal chimney where condensate - and hence sulphur attack - is less likely.

If you are advised to line - the most likely scenario - pumice is viewed as a superior material in many quarters, backfilled with weak leca (or vermiculite)/opc mix. DO beware damp ingress after any type of lining. A flue with a 'static' water ingress problem that wasn't noticeable previously due to the large surface area capable of keeping damp at bay, aided by a large updraft,, may suddenly be a real dripping problem post lining, water tracking down the lining through the excellent water-retentive properties of vermiculite. No surprise that nurserymen use it for that reason!

Clay not so good and prone to thermal shock. Cast-in-situ (perlite) very good in some circumstances, especially where structure is suspect. Stainless (flexi) is a variable commodity, both in material quality (we have taken many dozen 304 and 316 flexis out, tho the latest 904 is apparently better...time will tell), installation technique (big variable here) and in possible damage to the windings (look up chimney after lining!). Think ten years longevity if going the flexi route - you may get twenty, but unlikely much longer, no matter what the guarantee says.... ]]>