[Ghdp]

We have been told we have to line a chimney from a wood burner in  one room our new place. In time it will be a second sitting room ( dream on) but it is likely to be lit most evenings this winter. It is a fire only, no boiler. It is a multifuel stove but mainly used for wood. No surprise  it needs work and happy with the idea of lining. My query is this. We have been advised to insulate the lining with a sort of extra fleece at a cost of aroumd £250 plus vat. We are already wincing at the cost of the lining and labour  not to mention the new stove pipe and monitors etc This would be our fourth lined chimney in various places (which were done over the last 20 years and the last one was 11 years ago). Lining was not an option then. Why is a chimney lined and is it necessary. What potential future problems, if any, will we face.
Any thoughts folks?

[Creagan]

Two purposes behind lining a chimney:
- making a smooth, easily cleaned surface that won't allow soot to collect
- insulating the flue so that exhaust products do not condense leading to chimney fires

As woodburners have become more efficient, the need to insulate the flue has grown. This is simply because if more heat is being put out into the room, then less is going up the flue, and the colder the flue gases, the more you need to insulate the chimney to prevent them from solidifying before they reach the open air.

Some chimneys will be more vulnerable than others- for example, one on an external wall.

[Ghdp]

Goodness. That is clear and helpful. Why could the stove people not have explained! Thanks

[Womble]

There is a third reason:  Stove installers these days insist on lining chimneys because it then means they don't have to take responsibility for the condition of the existing stonework. Also, as you've noticed, they can charge an arm and a leg for installing the liner!

As Creagan says, the reason for insulating the lining is to reduce heat loss, thus keeping the flue gas temperature high. This basically makes the flue gases more buoyant, and increases the draw. Insulation can be either loose fill (vermiculite flakes or ceramic malteesers) or wrapped insulation jackets. The advantage of loose fill is that it's easy to do, and because you put it in after the liner, it doesn't make it any harder to fit the liner itself. The disadvantage of vermiculite is that it holds water (that's why it's also used as a soil improver), which can cause problems with stonework if you have any water penetration. The advantage of the insulation jackets is that they are mess free, and also protect the liner from puncture or denting during fitting. They are expensive though.

When we fitted a stove in our house, we found fitting the liner very easy indeed. The only problem was that when we poured in the vermiculite, it started coming down the adjacent fireplace too (oops! obviously a breach between the two chimneys somewhere). That meant that we then had to line the second chimney as well, and fill both with vermiculite  .

The stove installer had quoted us £1175 to supply and install the liner, plus £545 for chimwrap insulation, so that would have come to a shade over three grand to do both chimneys . Since even doing one of them was way over our budget, we bought the bits from hotline chimneys and installed them ourselves. That saved us about 2 grand all in all, so it's pretty significant. Note, I'm not saying everybody should DIY - just thought I'd explain what we did, in case it is of help to others.

And the result? Just the act of lining the chimney turned the existing stove in the second fireplace into an absolute  rocket, so much so that we melted holes in the ashpan the first time we re-lit it with the liner in place! Definitely worth doing IMHO!

Hope that helps!
 

[Ghdp]

Thanks for that too Womble. We have had some experience of wet vermiculite in a chimey on a gable wall shared with a nighbour who let it get wet Three years on and with lime plaster render on ourside and exposed stone on the other we are STILL drying out. Not going down that route!!! Think we should lick our financial wounds and get the liner