Double Skin Chimney

[chris w]

I am trying to source a double skin chimney for the wood stove. I can find several in local chandlers but they all have an inside skin diameter > 4 inches which is the size of the flue pipe on my boat. So I am looking for a 5 1/2" - 6" outer with an inner just under 4". Anyone know where I might find one?

 

Chris

[saltysplash]

I am trying to source a double skin chimney for the wood stove. I can find several in local chandlers but they all have an inside skin diameter > 4 inches which is the size of the flue pipe on my boat. So I am looking for a 5 1/2" - 6" outer with an inner just under 4". Anyone know where I might find one?

 

Chris

 

 

While searching for sweeping brushes this site came up which may or may not be some help

 

http://www.stovesonline.co.uk/wood_burning...nd-Chimney.html

[allybsc]

I am trying to source a double skin chimney for the wood stove. I can find several in local chandlers but they all have an inside skin diameter > 4 inches which is the size of the flue pipe on my boat. So I am looking for a 5 1/2" - 6" outer with an inner just under 4". Anyone know where I might find one?

 

Chris

 

We need one of these too after demolishing our chimney on a low bridge on the T&M, the flue "holder" on the top of the boat was made by the boatmans cabin co, so I took a quick look on the website, they have chimneys of various diameters and seperate flue liners that can be cut to size, our chimney was about the size of yours (I think) forgot to measure it before we left the boat...doh!!

Ally

[ChrisPy]

As far as I can recall, the 4" ID flue normally terminates in the roof-mounted chimney collar which has a socket for the top of the flue, 4.75" ID. The double skin chimney liner will slip down inside the upper part of the collar.

 

Do you not have a chimney collar, Chris?

[barge sara]

I am trying to source a double skin chimney for the wood stove. I can find several in local chandlers but they all have an inside skin diameter > 4 inches which is the size of the flue pipe on my boat. So I am looking for a 5 1/2" - 6" outer with an inner just under 4". Anyone know where I might find one?

 

Chris

 

Last time our NB chimney died, fed up with the short-life highly expensive cr*p sold as replacements, I went to our local heating engineers suppliers. They had a huge range of double skin stainless chimney sections. I came away with one 600mm long 125mm inner, 150mm outer and a huge jubilee clip. The 125 inner fitted around the outside of the inner spigot on the roof fitting.

 

Spray of black enamel, strip of brass, brass handle and some self tappers. Stainles steel chimney for less than £20!

 

But don't tell anyone, I'm thinking of going into production....

 

John MV Sara.

[chris w]

As far as I can recall, the 4" ID flue normally terminates in the roof-mounted chimney collar which has a socket for the top of the flue, 4.75" ID. The double skin chimney liner will slip down inside the upper part of the collar.

 

Do you not have a chimney collar, Chris?

 

 

The space between the inside of the collar and the 4" flue is filled with stove putty. I could of course dig some out to take a skin >4" diameter but this would mean that any tar would flow into that space rather than making its way back down the chimney which is what I wanted to achieve.

[GUMPY]

I always used a single skin one having got odd size collars, I had the chimneys made specially and then I used an insert either an inverted cone or as described below.

 

The simplest way to stop tar deposits is to find some thin ally sheet, roll it into a tube and then put it down the flue and let it unroll to the size of the flue.

Cut it level with the top of the single skin chimney and it cant then be seen.

The best sheet for this is lithoplates which as they are only used once and are then scrapped by the printers should be easy to find if there is a friendly local old style printer in your area.

When they start to rot after about 4-6 months just check them away and replace with a new one.

 

Did it this way for 10 years as a livaboard and never had any tar deposits on the paintwork.

 

Julian

Edited September 12, 2007 by idleness

[chris w]

I always used a single skin one having got odd size collars, I had the chimneys made specially and then I used an insert either an inverted cone or as described below.

 

The simplest way to stop tar deposits is to find some thin ally sheet, roll it into a tube and then put it down the flue and let it unroll to the size of the flue.

Cut it level with the top of the single skin chimney and it cant then be seen.

The best sheet for this is lithoplates which as they are only used once and are then scrapped by the printers should be easy to find if there is a friendly local old style printer in your area.

When they start to rot after about 4-6 months just check them away and replace with a new one.

 

Did it this way for 10 years as a livaboard and never had any tar deposits on the paintwork.

 

Julian

 

ooh thanks for this tip Julian - great idea.

 

Chris

[Keeping Up]

We have had a similar problem in reverse.

 

In the past our chimneys have always been the type sold typically at Midland Chandlers, where the steel is formed into a tube and then crimped. With these the inner liner always fitted snugly inside the collar, and was reasonably effective, but the chimneys have always rotted away quite quickly.

 

This year while at Stone I bought one of the alternatives, also sold by Tradline Fenders at Braunston, where the steel is welded instead of being crimped, and is also much thicker. Unfortunately I found it did not work as a double-skinned chimney, because the inner tapers down to less than 4 inches diameter, so the smoke gets up beiween the two liners and then condenses on the outer just as if it were a single-skin chimney.

 

Perhaps this style of chimney is what you were looking for Chris?

 

I have just filled the space between the two skins of ours, with expanding foam (which is available in fireproof grade) and I'll try it out next week.

 

Allan

[chris w]

Thanks Allan, sounds exactly what I need. I'll check their website.

 

Chris

[BlueStringPudding]

We have a Boatman stove which works a treat. We couldn't find a double skinned chimney to fit the collar so had to go for a single skin and a seperate inner liner. We now have tar on the collar, roof and tricking down the side of the boat!

 

Can't seem to persuade the liner to be effective. Perhaps using an expanding filler like Allan has would be the answer, but we have to take the chimney down so often, getting under bridges on the Stratford Canal that we'd have to redo it every couple of days.

 

Any suggestions?

[DHutch]

Well all your aiming for is an outer that goes over the collor and looks nice, usally forming most of the strenth of the thing.

- Then an inner, which fits inside the collor such that any condestate/tar will run down the flu towards the stove. Sheltered also by the outer.

- And then as allan pointed out, also doesnt let half the smoke go between the too, nullifying the whole double skin exersice in the process.

 

So as i understand it, allans foam, is between the two liners, rather than anything else.

- Thus he has performed the requments of the inner holding the flu gasses, and cause and condesation formed to drip down the flue not the paint.

 

We solved the problem by buying a stainless steel one from swindlers or simular.

- Its a little thicker than the cheap steel ones, but crimped together as they are. And just stainless to make it last.

- Then the inner was a little oversized, so it was cut into tabs at the bottom that where folded in a bit and silconed up.

 

 

 

Daniel

[Keeping Up]

I have just filled the space between the two skins of ours, with expanding foam (which is available in fireproof grade) and I'll try it out next week.

Having now tried this I can report 100% success. The insulating foam prevents the smoke from getting between the two skins, and there is no sign of any condensation (no tar running down the side of the boat hurrah!). In fact the only problem (which is a common one) was that if I put the coolie hat on top, there were a few drips of tarry condensation off its underside. That if anything proved even more that the foam was doing its job.

 

For anyone interested in repeating the exercise, I used a can of bright pink fireproof expanding foam from Wickes (£12.99), and filled the space between the skins about two-thirds full. It expanded beyond the end of the chimney so I scraped off the excess with a stick while it was still wet, then as soon as it was no longer tacky but was still soft (about 10 minutes) I put the chimney in place on the collar and left the foam to dry to a perfect fit. The chimney can be lifted off and replaced at will, and forms a good seal every time.

 

I only used a tiny amount of the foam, but the problem is that it sets in the nozzle and although they say it can be cleaned with acetone, I found it impossible to clean the nozzle, trigger, and delivery tube effectively. Ideally you need to get a group of you to share it all at once.

[Proper Job]

I only used a tiny amount of the foam, but the problem is that it sets in the nozzle and although they say it can be cleaned with acetone, I found it impossible to clean the nozzle, trigger, and delivery tube effectively. Ideally you need to get a group of you to share it all at once.

Does it work the same as most spray cans (with dip tubes)? If you turn the can upside-down and press, the 'propellant' clears the tube and nozzle. Or do they use the chemical reation of the foam as a propellant?

[ChrisPy]

Does it work the same as most spray cans (with dip tubes)? If you turn the can upside-down and press, the 'propellant' clears the tube and nozzle. Or do they use the chemical reation of the foam as a propellant?

I've used dozens of cans of ordinary grade poly foam. It isn't worth trying to re-use a can. You need to plan several jobs at once and use the lot within half an hour. The fireproof stuff can be used like the ornery grade to block holes, secure pipes, etc.........

[Keeping Up]

Does it work the same as most spray cans (with dip tubes)? If you turn the can upside-down and press, the 'propellant' clears the tube and nozzle. Or do they use the chemical reation of the foam as a propellant?

I'm not sure. Firstly it's confusing because it's one of the types that you use upside down anyway. When I'd finished I turned it the right way up and squeezed the trigger, that cleared it for a moment but then it just foamed up and blocked itself again so it may be that the foam is self-propelled..

[kimtre]

i have got a double skin pot and still get tar down the side of the boat can any one tell me how to get it off

[colin stone]

The spray foam cans have a little spigot on the top of the trigger assembly. After use bend the flexy tube back on itself and push onto spigot. Foam can will be useable for months.

[dove]

Last time our NB chimney died, fed up with the short-life highly expensive cr*p sold as replacements, I went to our local heating engineers suppliers. They had a huge range of double skin stainless chimney sections. I came away with one 600mm long 125mm inner, 150mm outer and a huge jubilee clip. The 125 inner fitted around the outside of the inner spigot on the roof fitting.

 

Spray of black enamel, strip of brass, brass handle and some self tappers. Stainles steel chimney for less than £20!

 

But don't tell anyone, I'm thinking of going into production....

 

John MV Sara.

 

Me too, just bought 6x3 sheet 304 stainless 22g 70 quid. going to make my own stainless liner (welded) with trad. tin and copper rivets on the outer. we'll see if it works

Andrew