Expensive chimney lining ?

[Tim Watts]

JimK wibbled on Friday 12 February 2010 19:09

Could be - I didn't look *that* closely. I assumed twin wall woul dhave a wall > 1/2" or more?...

[Tim Watts]

The Natural Philosopher wibbled on Friday 12 February 2010 20:38

Hopefully...

That bit is certainly true....

[Clive George]

Which basically means you can line an old chimney, a proper chimney or one which has been lined before.

What happened with yours then?

[js.b1]

I assume someone did a smoke test to prove the chimney needed lining?

Some chimney's do leak. Check under floorboards, in the loft, stack itself or feathers.

Some chimney's leak very little. Eg, a minute leak on an outside stack on a pressure test.

Some chimney's do not leak.

1950 brick, refractory tiles, enough fire cement to be a furnace, passed fine.

Feathers are the one to watch on unused or rarely used chimney if the mortar is weak or no rain cap. Acidic deposits of once coal burning eat into the mortar causing general degradation. So a proper pressure test (plate on top/bottom, smoke) is the only sure test.

[JimK]

leaky flues are only one reason to line a chimney so smoke tests not always indicated... e.g. to preserve/convert a chimney built to serve an open fire when installing a solid fuel stove, fitting a liner is a no-brainer (I would hope...!)

Cheers JimK

[The Natural Philosopher]

It was brand new and unlined..

[Piers Finlayson]

Our HETAS guy (mid-Wales) reckoned the liner would cost around a grand, so seems fair.

In our case he checked the existing unlined (external) chimney both using smoke and with a small camera and decided it was fine not to install a liner.

[JimK]

mmm what are you burning under it - (open, stove, wood, coal etc), how tall flue?, construction of flue?

Cheers JimK

[Clive George]

So a completely different situation from lining an existing chimney then, and you were talking out of your arse when you said "usually not allowed". Glad we've got that settled then.

Was it a cockup with the chimney built first?

[Stuart Noble]

Isn't that where the smoke comes out of more than one chimney

[Onetap]

The HEATAS guide of allowable flues, appliances, fuels, etc., is on- line;

only allow twin-wall flexible, but it looks like singe-wall from a distance.

See also the bit that says;

"These liners should give a normal life of 10 years or more when correctly installed, used and maintained. However, these flexible liners whilst being easier to install and replace are not permanent and prolonged periods of slow burning particularly using solid fuels, combined with inadequate cleaning of the flueways can cause corrosion damage which reduces the expected life of the liner to less than 5 years."

They are not permanent. People burn all manner of rubbish and the liners can tar up and corrode through in a matter of months. Good for their recommended use though.

There are other means of lining flues; mortar pumped in around an inflatable former, mortar rendering using a former winched up the flue,pre-cast liners (good for a straight-up chimney, not sure about off-sets).

[Adam Aglionby]

Years ago, 4 1/2 storey warehouse conversion where cafe bar put in basement, new open fireplace and chimney/flue (whats the difference?) installed, hit a major problem, chimney wouldn`t draw just filled room with smoke, think in end some sort of draw fan was pit in at top of chimney.

What causes this and how do you avoid it?

Thanks Adam

[The Natural Philosopher]

Gebnerally if its failed a test and needs lining, it needs lining properly.

yes, and the effing project manager still owes me for that and more.

[Onetap]

Flying guess; kitchen extract hood and/or inadequate/no fresh air make up?

[JimK]

shurely the BCO should have spotted that one?!

JimK

[JimK]

[JimK]

ahem

poured lightweight pumice type "concrete" linings are great as long as the installer does it properly and opens up the flue at *each* bend and makes sure the former is correctly spaced away from the inside of the bend (IYSWIM). I believe there can be a tendemcy for installers to "forget" this as presumably householders would be somewhat deterred if they knew the amount of mess and inconvenience....

JimK

[andrew]

I've had a 150mm ss rigid flue pinhole in well under 5 years on one commercial installation, combustion was fine but heat loss was too great and the acid condensate etched away in the anaerobic conditions. It didn't help that they were burning something that appeared to produce hydrogen chloride from the colour of the iron salt drips on the floor ;-).

Acknowledging that solid fuel appliances can burn a range of undesirable fuels is why HETAS stood out against derestricting the requirements for solid fuel appliances, such that they still have minimum diameter of 150mm and have to terminate above the eaves.

I had two of these done, in my current house, 20 years ago and can report that the material is wafer thin on the inside bends.

AJH

[Piers Finlayson]

Why?

[JimK]

why do you think?