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Jenna

Joined: 30 Sep 2005
Posts: 263
Location: Away with the fairies

Posted: Mon Jan 30, 06 11:02 am Post subject:
www.hotline-chimneys.co.uk (think the chimneys part is plural, if it don't work try without the 's') can do 904 for around £30/m, not found any cheaper than that. For a simple DIY method/advice, have a look in the big Collins DIY book if you have it - it'll at least give you an idea of whether you might be able to have a go!

Andy B

Joined: 12 Jan 2005
Posts: 3920
Location: Brum

Posted: Mon Jan 30, 06 11:20 am Post subject:

moongoddess wrote:

My understanding is that a liner will not *prevent* a chimney fire at all. It simply means that a fire is easier to contain and control. Tar, resin and soot will still build up inside a liner, but if you have a fire with a liner you should be able to shut the woodburner right down and starve the fire of oxygen.

Andy B, can you elaborate on how having a flue effects the way a woodburner works please?

Namaste
mg x

It should make the draw more efficient, make sure the smoke goes up the chimney. It depends a lot on the chimney though. Ours had three branches off it into other rooms where their was no longer a fire place. So their was the possibility of smoke finding its way into other rooms which a liner would prevent. It also helps to prevent the build up of tars, which could start a fire, because the extra contained heat gets them out of the chimney. You will still have to get it swept, but not as often.

Alchemist

Joined: 02 Mar 2005
Posts: 123
Location: Aberdeenshire

Posted: Mon Jan 30, 06 2:00 pm Post subject:

We put in a wood-burning stove recently and had the chimney lined at the same time. The main reason for it was that the existing chimney was too open and draw would have been insufficient. Modern stoves are something like 3x the efficiency of an open fire and as a result the exhaust gases don't heat the chimney as well, so as in our case, where the draw was a bit iffy even with the open fire, you'd get very poor draw indeed, as well as all sorts of nasties condensing on the chimney walls. Our lining is a flexible stainless tube (can't remember grade, but suspect it's 316 and single-wall) dropped into the chimney and then the space left in the chimney was filled with vermiculite, providing extra insulation. Draw through the stove is now very good.

Stacey

Joined: 18 Jul 2005
Posts: 8380
Location: Kernow

Posted: Mon Jan 30, 06 2:23 pm Post subject:
Isn't the best way to prevent build ups of tar making sure the wood is seasoned ( I don't mean with salt and pepper but has been 'weathered') ? It's in our tenancy agreement that we're not allowed to use green wood for that very reason.

Jonnyboy

Joined: 29 Oct 2004
Posts: 23956
Location: under some rain.

Posted: Mon Jan 30, 06 2:26 pm Post subject:
All this liner talk has got me a bit worried. Our builder knew that we were installing a woodburner and from watching the build they poured a concrete head and fitted what looked like a ceramic liner which went all the way up to the chiney top, they then built the chimney brickwork around it. Does this sound right?

sean
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 42207
Location: North Devon

Posted: Mon Jan 30, 06 2:29 pm Post subject:
Probably. Mostly people are talking about retro-fitting a liner in an existing chimney, so you use a flexible steel pipe. I reckon that's what it is anyway. Or you're doomed, of course.

Blue Peter

Joined: 21 Mar 2005
Posts: 2400
Location: Milton Keynes

Posted: Mon Jan 30, 06 2:30 pm Post subject:

stacey_guthrie wrote:

Isn't the best way to prevent build ups of tar making sure the wood is seasoned ( I don't mean with salt and pepper but has been 'weathered') ?

It's in our tenancy agreement that we're not allowed to use green wood for that very reason.

I think that you mean that it's moisture content is low - 'seasoned' is the correct term, but I don't think that 'weathered' is. A lower moisture content means that there is less water (in the wood) to heat when the log is burned, so that it burns at a higher temperature, which means that the combustion is more complete (so less tars are deposited),

Peter

Jonnyboy

Joined: 29 Oct 2004
Posts: 23956
Location: under some rain.

Posted: Mon Jan 30, 06 2:30 pm Post subject:

sean wrote:

Probably. Mostly people are talking about retro-fitting a liner in an existing chimney, so you use a flexible steel pipe. I reckon that's what it is anyway. Or you're doomed, of course.

That's what I was thinking, but as nobody has mentioned ceramics I was half expecting to be doomed,

Jenna

Joined: 30 Sep 2005
Posts: 263
Location: Away with the fairies

Posted: Mon Jan 30, 06 2:34 pm Post subject:
would have loved a ceramic liner - no chance of that burning through, hehehe! Would have to make a bunch of holes into the chimney to fit the 'bits' together - too much faff in a retro fit situation.

Alchemist

Joined: 02 Mar 2005
Posts: 123
Location: Aberdeenshire

Posted: Mon Jan 30, 06 4:13 pm Post subject:

stacey_guthrie wrote:

Yup. We were given all sorts of dire warnings about using properly seasoned wood when our stove was installed. A web-site I found when I was looking at getting the stove originally says the following:

cosi.co.uk wrote:

CHIMNEY LINING/TAR FORMATION.

There are three stages in the combustion of wood. The first stage is when the water boils off. Yes, there is a lot of water even in dry, seasoned wood. A small log will contain over 1/2 pint even when it registers only 20% moisture content with a meter. During the second stage, the resins in the wood are boiled to form hydrocarbon gases, these form the yellow licking flames when burnt (just like a gas effect fire!). It requires a hot secondary air supply preferably 300-500 deg.C. (as in air wash or properly designed wood burning stoves) to burn these gases, but remember, if you do not burn them you waste approximately 1/3 of the energy in the log and you will send the boiling resins up your chimney to condense on the chimney walls. Finally you will be left with the charcoal, clean heat, almost pure carbon, that will combine with oxygen from 150 deg.C. plus to form carbon dioxide and heat. Of course all the three stages are going on simultaneously at any time during the normal running of the stove or fire, but the understanding of the process highlights some of the design and system running methods.

Burn only dry wood. If you are serious about burning wood you must sort out supplies and the relevant storage problems. The wood must be bought, sawn and stored under cover the season before you require it.

Make sure you have a stove with a hot secondary air supply.

Open the stove up every time you reload to allow the gases to be burnt.

Chimney design: Insulated chimneys are essential for burning wood. Even the best stove, run properly with the best dry wood will let boiling resins up the chimney. These condense at approx. 150 deg.C., if the chimney is well insulated they will not condense out, but a standard chimney will gradually get saturated in foul smelling tar, which is also a fire hazard. It will first be noticed in the loft area but gradually get lower until tar stains appear in the upstairs chimney breasts.

oldhibberd

Joined: 09 Mar 2005
Posts: 118

Posted: Mon Jan 30, 06 4:34 pm Post subject:

Pretty sure Chimney will HAVE to be double lined for any Solid fuel.

As I understand it a metal liner will burn/rot through in 10-15 years, depends how well seasoned the wood is, and whether or not you burn coal. The alternative is a Pummice liner (Isokern) not much more expensive to buy, just more difficult/expensive to install. But that should last 40+ years. You can also get a lining, where they shove an inflatable sausage down the Chimney then pour this heat proof concrete (Thermocrete) .down to form a flue.

Alchemist

Joined: 02 Mar 2005
Posts: 123
Location: Aberdeenshire

Posted: Mon Jan 30, 06 5:50 pm Post subject:
Yeah, the steel ones don't last forever, sadly. I think ours has a 20-yr warranty, but it just hangs from a bracket at the top, so you can just drain out the vermiculite from the dead-space and pull the liner out through the chimney-pot if you need to. I think I looked at the pumice-type liners about the time we were doing ours. Very good, but a fiddle to fit

moggins

Joined: 24 Feb 2005
Posts: 942
Location: Gloucester

Posted: Mon Jan 30, 06 6:44 pm Post subject:
That Thermocrete stuff sounds great

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