CHIMNEY FLUE TYPE

[cmarshy201]

I am looking into installing a DEFRA approved wood burning stove but have a question regarding the chimney. The house was built in the late 60's and they were built with chimneys and a fireplace to accept an open fire if the buyer wanted one.I know this because my parents bought the house from new and i have recently purchased the property from them. Now the gas fire has been removed (there has only been gas fires installed),when you look up the chimney,it is lined with what looks like round pot sections slotted into each other going right up the chimney,which measure 8" internal diameter. My question is, is this whats known as a pre-cast flue and would this be sufficient for a wood burning stove? I have tested the chimney with a smoke bomb and the drag is really good.Any comments would be much appreciated,thanks, Chris.

 

[stuart45]

Flue liners became part of the Regs in 1965. A pre cast flue is usually a concrete block system which becomes part of the internal skin.

 

[cmarshy201]

Thanks for the reply. Would the flue liner that i mentioned be suitable for a wood burning stove?

 

[Richard C]

Installing a wood burning stove is controlled building work; unless you use a HETAS installer, you need to notify to LABC for test & inspection in order to get a compliance certificate; if you don’t have one you could have problems when you sell & it may invalidate your house insurance claim in the event of a problem.

Modern gas flues are not generally suitable for solid fuel but if you have class one clay flue liners it may be suitable. However if its 40 years old & you can never be sure; an 8” flue is also rather large for a domestic output stove. For wood/solid fuel stoves, an insulated flue 5”/6” SS will keep the flue temperature up which gives better draught, efficiency & prevents build up of corrosive tar in the top of the liner where it is coolest.

Read this lot also;
As this comes up so often, I’ve put together this generic post; read the links but not all may apply to you.

You can DIY but you need to understand the Building Regs (which changed in October), submit a Building Notice & pay a fee. Your LABC will inspect &, assuming everything is OK, issue a compliance certificate; the BI may want to witness smoke & spillage tests.

Lots of archive threads on this, & other things you have to watch out for, here a few links for you to read:
http://www.stovesonline.co.uk/stove_building_regulations.html
http://www.hetas.co.uk/public/certificates.html
http://www.solidfuel.co.uk/pdfs/buidling_regs_consumer leaflet.pdf
//www.diynot.com/forums/viewtopic.php?t=183614
//www.diynot.com/forums/viewtopic.php?t=211524
//www.diynot.com/forums/viewtopic.php?t=242738
//www.diynot.com/forums/viewtopic.php?t=224751

& some more sobering just in case you think it’s all a load of old tosh:
http://www.solidfuel.co.uk/main_pages/news.htm
http://www.dailymail.co.uk/news/art...wood-burning-stove-leaks-carbon-monoxide.html

Also get at least 3 quotes from local independent HETAS installers:
http://www.hetas.co.uk/nearest_member

You might be pleasantly surprised & you should ask yourself if you really want all the hassle & risk getting it wrong; climbing onto the roof with an 8M stainless steel snake on your back is not for the feint hearted!

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[cmarshy201]

Thanks for reply Richard. I have give up on the DIY approach after reading your posts,didnt realise there was so many things to consider on the legal side.
Got a few names of local HETAS engineers/installers, had one round over the weekend,checked my chimney liner which is fine(big expense saved),just needs a new cowl on the chimney pot.
Now bearing in mind that i have the stove,register plate,various lengths of 5" flue pipe and even some fire cement,he said it would cost £650,does this sound a bit steep or is it just me???

Just one more thing,i was thinking of tiling the area around the stove,sides and back,read conflicting reports about ceramics being ok coz they are fired in a kiln when made etc,some say they will end up like crazy paving but some say just rendering with sand and cement is the only way. Apologies for what probably are daft questions

 

[Richard C]

Now bearing in mind that i have the stove,register plate,various lengths of 5" flue pipe and even some fire cement,he said it would cost £650,does this sound a bit steep or is it just me???

What exactly do you mean by “various lengths of 5” flue pipe; you need a CONTINUIOUS length of NEW twin wall stainless steel flue pipe & whilst 5” is OK ish for a wood burning stove, 6” is a much better proposition & will allow multi-fuel burning. Many HETAS installers won’t fit anything less than 6” now anyway as it’s marginal & does not comply with BR's for multi-fuel burning. A reasonable price for a new quality 6” liner installation + pot cowl, register plates, granular vermiculite insulation between the old & original flues, installation of your stove commissioning, certification & specification plate should be between £850 - £1100 max IMO but this would not include provision of permanent ventilation (if required) or any building work associated with the fire opening or hearth. This breaks down roughly equal to around £450 -£500 for the liner & ancillaries & £450+ for fitting, testing & certification. It shoul only be a day’s work really but it’s pretty hard graft & it can be a long day if things go wrong. Personally I would be reluctant to use what you have already unless it’s new & entirely suitable for the job. Get at least 3 quotes, let each know they are in competition with others & get written quotes (not estimates) which form a part of your signed contract with them.

Just one more thing,i was thinking of tiling the area around the stove,sides and back,read conflicting reports about ceramics being ok coz they are fired in a kiln when made etc,some say they will end up like crazy paving but some say just rendering with sand and cement is the only way. Apologies for what probably are daft questions

Tiles or rendering, it depends on what you want; but read all the links & do a forum search for “stove installations”. Believe me it’s all come up before & the answers are in there somewhere but if you can’t find them come back.

 

[mointainwalker]

Richard

Are you saying that in the UK only a flexible liner is allowed to re-line an existing chimney ( had a look at the quoted regs but found them to be ambiguous/badly written ).

I am puzzled as i live in the French Alps where 95 % of houses have stoves and that stuff is unknown. It is all one metre lengths of single/double-skin.

 

[hotrod]

I am puzzled as i live in the French Alps where 95 % of houses have stoves and that stuff is unknown. It is all one metre lengths of single/double-skin.

Most chimney's that require re-lining require approx 9-10m of flue liner. How do you think the install can be achieved using 1m sections? Think about the practicalities of the flue wandering off centre and the way you often have the "flue gatherer" just under the stack.

 

[mointainwalker]

All flues I know about here are straight and single-flue - sometimes built on outside in old buildings.

Usual existing flue is interlocking blocks of 200 mm/300 mm cross-section. In my case I fitted four metres of single-skin 180 mm pipe into 200 mm blocks

However that is irrelevant to my question to ask if only single-piece flexi-liners are permitted in UK under any circumstances.

 

[Richard C]

Richard

Are you saying that in the UK only a flexible liner is allowed to re-line an existing chimney ( had a look at the quoted regs but found them to be ambiguous/badly written ).

I am puzzled as i live in the French Alps where 95 % of houses have stoves and that stuff is unknown. It is all one metre lengths of single/double-skin.

I suppose you could use a rigid liner but good luck with getting an 8-10m length of that delivered let alone get it down an existing flue; & how the hell do you seal 8-10 x 1 metre lengths of flue liner unless you do it as it was being inserted & I cant see the point of that when you can get a flexible twin wall SS liner delivered coiled in one continuous length.

I live in the UK & I understand the British BR’s; I don’t necessarily agree with all of them but, in this case, I don’t find them ambiguous or badly written. To be frank, but not unfriendly, I don’t really give a toss what you do in the French Alps!

 

[mointainwalker]

Richard

Don't you find it interesting what happens in other countries ?

I do because different practices give you the opportunity to ask why "a" is legal in one country but not another, and if it is simply unnecessary regulation.

I installed my stove here completely legally as there are no restrictions on private individuals.

An interesting point of difference is that there is no sealant used between individual lengths of flue-pipes, just interference fit. I was rather surprised at this when I bought my flue but was clearly told when I asked about a "mastic or similar" that it is not used.

As for flex-liners, believe I recall reading - and it seems logical - that they are more difficult to clean properly and are therfore more prone to chimey fires.

 

[Richard C]

Don't you find it interesting what happens in other countries ? I do because different practices give you the opportunity to ask why "a" is legal in one country but not another, and if it is simply unnecessary regulation.

Yes I find it interesting to a point but how any particular country regulates is largely a result of circumstance. I gave up stressing about the injustice of unnecessary & over regulation a long time ago both here in the UK & abroad because there is nothing I can do about it. At the end of the day I still have to comply, all I do is make sure I fully understand the rules & use that to my advantage. Having spent a good part of my previous working life overseas, I have a fair amount of experience in how legislation differs in other countries but they all seem to have their fair share of what appears to be illogical regulation/legislation. In the industry I previously worked in, I found the UK was mostly ahead of anything I came across abroad from a technology & operational practices viewpoint & is why I was always kept very busy.

I installed my stove here completely legally as there are no restrictions on private individuals.

Sounds like utopia compared to the over restricted regime we now have I the UK but from what I came across on a daily basis, it seems we may have more than our fair share of cowboys, chancer’s & numpties. Problem is that more regulation never stops them operating, it just makes life that much harder for the rest of us.

An interesting point of difference is that there is no sealant used between individual lengths of flue-pipes, just interference fit. I was rather surprised at this when I bought my flue but was clearly told when I asked about a "mastic or similar" that it is not used.

I’m not sure I’d be happy with that; the units would need to be quiet accurately made & what exactly holds the lot together apart from friction; but then you still have the “numpty factor” of the person fitting/installing it.

As for flex-liners, believe I recall reading - and it seems logical - that they are more difficult to clean properly and are therfore more prone to chimey fires.

Certainly more difficult to clean so I suppose that would mean they are more prone to fires.