flue liners

[Penners]

I really need to make a decision this weekend and am beginning to think I'm over-analysing the whole thing.

No, I don't think so, FF. It is a difficult decision - particularly when the cost of double-wall insulated liner is so eye-watering.

One other factor that I don't think has yet been mentioned is the height of the chimney. Obviously the further the combustion products have to travel up before escaping from the liner, the more they're going to cool. I have a feeling (but no empirical evidence) that the amount of chimney that sticks up above the roof may also be a factor. Obviously a chimney above roof height, with the wind whistling around all four sides of it, is going to lose more heat that one that's inside the structure of the house.

There - that's made your decision easier, hasn't it? :?

 

[Andrew Bodenham]

Shelli,

Different products for different aplications. Rigid double skinned pipe tends to be used where the flue is visible, or has to run through parts of a building and is not enclosed in a structure such as a chimmney, and is designed to be structurally self-supporting. An example would be barn conversion with no existing chimney - the flue could be assembled from rigid pipes bracketed to the wall internally. They contain insulation between the inner and outer skin to reduce heat loss and allow closer proximity to flammable surfaces than would be the case with a single skin pipe.

Flexible liners are used exclusively for refurbishing existing chimneys, and rely on the masonry of the existing flue for support. They are an economical way (compared to complete rebuilding) of providing a gas-tight, reliable flue. The double skin allows the use of a heavily corrugated outer for strength and flexibility, lined with a relatively smooth inner layer for good gas flow and ease of maintenance (sweeping). The current debate on insulation is interesting - I believe that flexible liners should be insulated, and the reasons have been well explained. The insulation can be in the form of pre-formed fibreglass sections, a one piece fibreglass jacket, or a granular insualtion such as vermiculite which is poured in around the liner after installation. There are pros and cons with each system.

For what it's worth I lined one of our flues a while back using a flexible liner obtained from stoves-online, and using their excellent Chimwrap insulation jacket. other components were obtained from Fluestore: http://www.fluestore.com/
Both companies provided excellent service.

Remember that a 10 year warranty is just that. It's a minimum working life. If the flue is carefully installed, regularly swept, and only dry wood is burned then the actual life before failure should be a great deal longer than the warranty period. We had our first flue done 11 years ago, and visually the liner looks as good now as it did when installed. OK, perhaps a bit more sooty.

Hope this makes things clearer for you.

 

[shelli]

Andrew - I've always liked you - thanks a million!

The fog is lifting slightly - thank you for saving me from a weekend of flue induced despair and despondency.

I will do the business and get it ordered - enough prevaricating around the large leafy things

I have purpose - no-one dare post anything else "useful" to throw me into confusion as am a bear of very little brain and every time I learn something new some of the old stuff gets pushed out through ears

Love Shelli (now well adjusted once again) X

 

[Penners]

Andrew - I've always liked you
Love Shelli X

Brazen hussy. She's anybody's for a Chimwrap insulation jacket.

 

[Flyfisher]

Yes, thanks for that helpful summary Andrew. Your comments about the 10-year warranty being a 'safe' minimum makes sense considering the very variable operating conditions that these stoves can work under. From raging dry wood to simmering damp stuff, the amount of tar/acid condensation must vary enormously.

Penners' point about the length and exposure of the chimney is also valid in terms of insulation. The one I'm currently working on is on a gable wall but internal and only about 1m above the roof. Thus, only one side is external and the walls are pretty thick so I think I'm going to opt for a flexible double-skin liner with no insulation.

 

[shelli]

Aha - this brings to the fore answers another point that came up in "discussion" this weekend (am so grateful for this forum ) - the woodburner chimney is on a gable end wall - north wall and not exposed to the weather but external - so insulation and flexi liner is the way we are going. the other chimney is in the middle of the house and the fire is an open georgian hob grate - do we need to line this one?

Shelli x

 

[Penners]

I wouldn't bother to insert a flue liner for an open fire - unless the chimney was giving problems. Indeed, flue liners for open fires can bring their own problem of insufficient capacity.

 

[shelli]

thanks Penners - houses eh!

I didn't even think about this until yesterday - have been assuming (and we know what that does) we needed both chimneys lining - we could have been toasty warm in the lounge all this time.

 

[Penners]

Just be careful when you light your first open fire. Have a good look around at every level of the chimney stack, to make sure that there are no smoke leaks.

PS: A revolting business consultancy lecturer that I once heard said: " 'Assume' makes an 'ass' of 'u' and 'me' ".

:roll: :roll: :roll:

 

[shelli]

vile aren't they - the way they pimp our language

we've had this link before - but I like it

http://news.bbc.co.uk/1/hi/magazine/7457287.stm

 

[shelli]

This is useful if you need to communicate with one of them

http://www.plainenglish.co.uk/generator.htm

 

[Penners]

Yes, I think we've got our ducks in a row on that paradigm. After all, there's no 'I' in 'team'.

 

[shelli]

On balance, from this side of the desk it might be better to park the issue.



- before it gets silly - you know how they hate it when it gets silly!!

 

[Flyfisher]

I wouldn't bother to insert a flue liner for an open fire - unless the chimney was giving problems. Indeed, flue liners for open fires can bring their own problem of insufficient capacity.

I agree. I've read that an 8-inch liner is the minimum for an open fire.