Insulated twin wall stainless steel chimney flues for a solid fuel stove

PureBred

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Would i need a steel flue here. Any ideas about what i should do would be appreciated. Want to put in a stove but want to recess it into the wall like a inglenook. Could i just frame out the chimney with timber or is that dangerous?

PeteHeat

Hi,

Is there timber behind the wall in picture P8230103.JPG ?

In its present condition I reckon you could fit almost any type of stove, however you do need a chimney.

Take care not to confuse a flexible liner with a flue, a lot depends on what I can't see before offering definite advice.

If you want to use a timber frame to form a chimney breast take care to ensure it is clad in fireproof material especially on the inside where it can't be seen.

Also use the rules for combustibles as minimum guides, pages 6 > 11 of this document is a good guide http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1650,en.pdf

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PureBred

PeteHeat wrote: »

Hi,

Is there timber behind the wall in picture P8230103.JPG ?

In its present condition I reckon you could fit almost any type of stove, however you do need a chimney.

Take care not to confuse a flexible liner with a flue, a lot depends on what I can't see before offering definite advice.

If you want to use a timber frame to form a chimney breast take care to ensure it is clad in fireproof material especially on the inside where it can't be seen.

Also use the rules for combustibles as minimum guides, pages 6 > 11 of this document is a good guide http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1650,en.pdf

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Thanks Pete for the advice and links.

Ya thats a timber beam. Will be take out and filled with concrete!

Would a flexible liner surrounded in insulation and then plastered over not do???
The pics should show two old fireplaces to the left and right of the new opening. I have cut out a new channel to try and find one of the old chimneys, which ended up being the one on the left. The idea was the to just run a flexible steel liner from the stove all the way to the top of the chimney by tapping into the 'old chimney run'.

Pic below.

Thanks.

PureBred

Here

PeteHeat

Hi,

It doesn't look like you will have enough room / depth for 100mm wall as well as the flue in the space you have opened up.

Leaving the building regs aside I would expect the heat from a flexi liner to be constant problem cracking the chimney breast along the two lines of the opened channel.

The flexi liner gains a lot of strength from being fitted inside existing flues and being back filled with vermiculite, it also gets to expand if needed as the vermiculite works as both a cushion and insulation.

Back filling the channel will be a job as you don't have the benefit from a bond you get in the block work when building a new chimney.

The old chimney appears to have been a poured structure, possibly a concrete mix with some large stones used, they were prone to cracking especially if the chimney ever went on fire.

An option that may help you especially forming an inglenook would be to build a new facing wall out of stone or similar finish

Fair dues to you cutting the old flue / chimney breast out, that was a lot of work !

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PureBred

Ya its a mass concrete house. Hard to knock that stuff alright.

So what if I was to fit the liner and then build a block wall all the way up to the ceiling untill the liner enters the old chimney.

PeteHeat

Hi,

Because I am not standing in front of the wall I am probably being a bit over cautious with this suggestion but it would work.

Fit a twin wall insulated flue with the correct diameter to suit your stove, (either 5" or 6"), get the correct adapter from twin wall to high temperature flexi liner and connect as near as possible to the top where the channel meets the existing flue.

That should leave you with a small part that needs to be insulated, the flue manufacturer should be able to supply a few feet of the same insulation they use inside the twin wall to wrap around the small piece of flexi exposed where it joins to the twin wall.

That should alow you to choose from a few different finishes inside the room, you may be able to save by having a local installer call and have a proper look.

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PureBred

PeteHeat wrote: »

Hi,

Because I am not standing in front of the wall I am probably being a bit over cautious with this suggestion but it would work.

Fit a twin wall insulated flue with the correct diameter to suit your stove, (either 5" or 6"), get the correct adapter from twin wall to high temperature flexi liner and connect as near as possible to the top where the channel meets the existing flue.

That should leave you with a small part that needs to be insulated, the flue manufacturer should be able to supply a few feet of the same insulation they use inside the twin wall to wrap around the small piece of flexi exposed where it joins to the twin wall.

That should alow you to choose from a few different finishes inside the room, you may be able to save by having a local installer call and have a proper look.

.

Thanks Pete,

So what your saying is to put the insulated flue connecting all the way from the stove to the connection with the old chimney, and the put the flue liner from there to the top(outside).

Note: I don't think the old chimney is lined. Just looks like it was framed in concrete when the house was built. Maybe i need to run the twin flue all the way to the top of the chimney.

Here is what i think your saying anyways.

PeteHeat

Hi,

Thats the general idea, maybe a 45 degree bend at the top with an adapter to the flexi which would continue to the top of the flue.

It would be tight but you would have the benefit of the adapter inside the old flue and allow the vermiculite to take care of the rest.

The possible problem with extending twin wall into the old flue is the outer diameter would most likely be too big to fit, for example the outside diameter of (5") 125mm twin wall is 180mm and (6") 150mm is 200mm.

Before buying any flue parts choose your stove as you will be working to the diameter of the spigot off the stove, also you will need the height of the stove to decide where the flue starts.

Best of luck with the installation.

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PureBred

PeteHeat wrote: »

Hi,

Thats the general idea, maybe a 45 degree bend at the top with an adapter to the flexi which would continue to the top of the flue.

It would be tight but you would have the benefit of the adapter inside the old flue and allow the vermiculite to take care of the rest.

The possible problem with extending twin wall into the old flue is the outer diameter would most likely be too big to fit, for example the outside diameter of (5") 125mm twin wall is 180mm and (6") 150mm is 200mm.

Before buying any flue parts choose your stove as you will be working to the diameter of the spigot off the stove, also you will need the height of the stove to decide where the flue starts.

Best of luck with the installation.

.

Thanks Pete ur a legend. Can see it more clearly now.

So to finish it off i would just fill in around the twin wall with vermiculite all the way down and leave just the flue liner on its own all the way to the top of the chimney? Wouldn't really be able to fill that up.

Cheers again.

PeteHeat

Hi,

Actually reverse with the vermiculite, the twin wall looks after itself no need for back filling a space around it will do no harm.

You back fill around the flexi from the top of the chimney, you have to get up there up there anyway to fit the bracket that holds the flexi in place and the cap to finish it off.

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dafeens

Can you tell me if an exterior TW SS flue can be painted with a high temperature paint? and will it be durable to the weather.

Thanks

CJhaughey

dafeens wrote: »

Can you tell me if an exterior TW SS flue can be painted with a high temperature paint? and will it be durable to the weather.

Thanks

You could probably try VHT spray paint or BBQ paint, however SS is not easy to get paint to stick to. I would leave it as SS TBH rather than have patchy paint.

PeteHeat

Hi,

I am inclined to agree with CJhaughey as nothing looks worse than flaking paint.

One solution we came up with for a twin wall that came through a slate roof on the front of a house was to have a plastic coated sheet metal formed to go over the flue, the total length was about 1 metre and more expensive that the flue but it's still looking good.

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