Chimney collars....

[casper ghost]

We fitted the stove into Sleepy Hollow this weekend.. Why is it that these chimney collars do not accept a standard 5" flue pipe. It makes the task of fitting a stove much more difficult. We had to cut slots into the top of the flue and "squeeze" it up the flange.

The internal diameter of the flange was about 1/8" to small for the flue pipe .Casp'

[Ark Right]

We fitted the stove into Sleepy Hollow this weekend.. Why is it that these chimney collars do not accept a standard 5" flue pipe. It makes the task of fitting a stove much more difficult. We had to cut slots into the top of the flue and "squeeze" it up the flange.

The internal diameter of the flange was about 1/8" to small for the flue pipe .Casp'

 

Hi, Roof collars usually come in two sizes five and six inch, a six inch collar will take a five inch flue with enough room to get the necessary fibreglass rope and sealant in. Your description of fitting the flue pipe does not make for a good installation and may lead to problems not only in the flue gases not clearing properly which of course can have serious consequences but also flue residues leaking into the boat down the flue pipe.

 

Ark Wright

[blackrose]

We fitted the stove into Sleepy Hollow this weekend.. Why is it that these chimney collars do not accept a standard 5" flue pipe. It makes the task of fitting a stove much more difficult. We had to cut slots into the top of the flue and "squeeze" it up the flange.

The internal diameter of the flange was about 1/8" to small for the flue pipe .Casp'

 

I think the standard 6" OD collar accepts a 4 & 1/2" OD flue? Most boats don't have flues bigger than this.

 

In order to avoid reducing the 6" flue of my Morso Panther which is contrary to their fitting instructions, I had an (approx) 6 & 3/4" section of pipe welded into the roof to act as a collar. In fact this didn't really help matters because a wider diameter flue is more likely to require a full length flue (4m) to get a decent draw as there is a correlation between the two.

 

In the end I got rid of the 6" flue inside the boat and reduced it, but I still have a 6" diameter chimney. However, if you're going to reduce the diameter of a flue it has to be gas tight and there should be an expansion gap where it goes through the collar.

Edited September 26, 2010 by blackrose

[casper ghost]

Gas tight isn't a problem, most stoves aren't actually gas tight, it's the draw that keeps the smoke going up the chimney. My Dad used a 5" flue on his Squirral, he just ended it at the collar and put a narrower pipe down into it from above and then gunked around it. That was years ago and so far it's been ok.

Casp'

[cheshire~rose]

We recently has the flue pipe replaced because it has started dripping tar and rusty water down inside the boat. As far as we are aware it was the original flue pipe on a boat built in 2004.

 

We had been using the stove perfectly happily and without any cause for concern until we got the drips coming in. It turns out the flue had been incorrectly fitted into the top flange at an angle allowing, over time, the acidic deposits to build up on the edge and east away at the flue pipe until it completely corroded away and not only dripped nasty stuff on the stove top but it seems has made a bit of a mess of the entire roof area under the flange. Thankfully this never actually showed itself but it means the roof lining of the boat is at present hiding a multidue of sins caused by acid condensation seeing in around the incorrectly fitted pipe. It is perhaps a very good job we got the messy drippy problems investigated sooner rather than later as the damage could have been much more severe if we had not investigated sooner.

The other bonus is that now we have a properly fitted flue pipe the fire draws so much better and is much more responsive and well behaved too!

 

It certainly sounds like the current fitting might benefit from a rethink because it is likely you could be storing up potentially expensive problems.

[casper ghost]

I wouldn't say that what we have done is going to cause any problems, the flue is neatly fitted into the collar and gunked around, what seems odd is that why these collars aren't made to fit the standard 5" flue. My fire has a 4.5" flue which is a heavy steel tube, it seems to have too much of a gap where it enters the collar.

Casp'

[blackrose]

Gas tight isn't a problem, most stoves aren't actually gas tight, it's the draw that keeps the smoke going up the chimney. My Dad used a 5" flue on his Squirral, he just ended it at the collar and put a narrower pipe down into it from above and then gunked around it. That was years ago and so far it's been ok.

Casp'

 

I can assure you that a flue that's not gas tight is a problem. It's not the same as a stove not being gas tight! Small gaps around stove doors etc will draw in air because it is at the bottom of the system, but if the top of a flue is not gas tight it may release carbon monoxide into the boat.

 

I'm not sure I understand the description of your dad's flue installation, but a flue is supposed to go inside the collar. Personally I would rather follow recomended safety advice on all my installations. If we just adopt the "nobody has died yet" approach it doesn't necessarily mean the installation is safe.

Edited September 27, 2010 by blackrose

[blackrose]

I wouldn't say that what we have done is going to cause any problems, the flue is neatly fitted into the collar and gunked around, what seems odd is that why these collars aren't made to fit the standard 5" flue. My fire has a 4.5" flue which is a heavy steel tube, it seems to have too much of a gap where it enters the collar.

Casp'

 

That's an expansion gap.

[casper ghost]

That's an expansion gap.

My 4.5" diameter 5mm thick steel pipe is never going to expand by 1/4".

 

The flue we have just fitted is gas tight, I don't think I said it wasn't. As for others being gas tight, i'd bet that if when the fire was going you went outside and blocked the chimney, smoke would come out everywhere from your gas tight installation.

Casp'

[ChrisPy]

My 4.5" diameter 5mm thick steel pipe is never going to expand by 1/4".

 

in this case the expansion gap is something you fill with a compressible sealant (e.g. rope) to maintain gas tightness.

just like a sealant-filled expansion joint in a road or other structure.

if the gap closed up completely it wouldn't work, would it?

[Doorman]

Hi, Roof collars usually come in two sizes five and six inch, a six inch collar will take a five inch flue with enough room to get the necessary fibreglass rope and sealant in. Your description of fitting the flue pipe does not make for a good installation and may lead to problems not only in the flue gases not clearing properly which of course can have serious consequences but also flue residues leaking into the boat down the flue pipe.

 

Ark Wright

 

Quite right, Ark Wright!

Edited September 27, 2010 by Doorman

[blackrose]

My 4.5" diameter 5mm thick steel pipe is never going to expand by 1/4".

It doesn't need to expand by a 1/4 inch! You pack the gap with glass rope and seal the top with high temp silicone sealant. 1/4 inch is a perfectly fine expansion gap.

 

The flue we have just fitted is gas tight, I don't think I said it wasn't. As for others being gas tight, i'd bet that if when the fire was going you went outside and blocked the chimney, smoke would come out everywhere from your gas tight installation.

Casp'

I didn't say your installation wasn't gas-tight either - I haven't seen it. All I said was that any flue installation must be gas-tight.

 

If I did what you suggested smoke wouldn't leak out "everywhere" because I did the job properly. Smoke would come out from gaps around the doors of my stove, but NOT from the top of the flue inside the boat.

 

I think you should have taken advice from others before you did the job, not afterwards as you obviously don't like to hear how it should be done.

 

I think I'll leave you to it...

Edited September 27, 2010 by blackrose

[casper ghost]

I think you should have taken advice from others before you did the job, not afterwards as you obviously don't like to hear how it should be done.

 

I think I'll leave you to it...

Thanks for the replies, but if you re-read my thread you'll see I wasn't asking for any advice, mearly moaning about the size of the normal collars that are sold. I'm completely happy that the installation is safe.

Casp'

[blackrose]

Ok you didn't directly ask for advice, but if you're going to tell us all about botching a flue installation then I think you've got to expect a bit of advice on how to do it properly.

[blackrose]

Ok you didn't directly ask for advice, although I still think you should have. The point is if you're going to tell us all about botching a flue installation then I think you've got to expect a bit of advice on how to do it properly.

Edited September 27, 2010 by blackrose

[exboater]

I installed a squirrel stove during the refitting of my boat. Don't know if this was an approved procedure, but was cheap and easy to do.

 

1. Cut 4" diameter (I think, can't remember the exact dimension) steel pipe to correct length and rake.

 

2. Cut hole in roof to suit, a little larger than pipe to allow for expansion/vibration.

 

3. Fabricated steel flange 1/2" thick to serve as an integral collar.

 

4. Welded flange to pipe in situ so as to achieve correct angle for roof profile.

 

5. Cut asbestolux sheet for underside of roof.

 

6. Lowered pipe/flange assembly through roof from above, sealed stove collar with asbestos rope.

 

7. Bolted flange to roof through the asbestolux.

 

8. Placed chimney on pipe, lit stove.

 

This installation proved to be problem free in the subsequent five years I owned her.

[soldthehouse]

Emerging from the fog, I say ,do as your told Casper!!! [for once ]