Flue - what a nightmare.

[Tracy D'arth]

Why would you want a 6" flue on a boat?

Use 4 1/2" OD pipe with a reducer in the stove collar and a 5" ID standard roof collar.  There are reducers in the chandlers.

Edited October 6, 2023 by Tracy D'arth

[Hoorayforboobies]

That’s what I was thinking! 
 

trying to find 6”-4 1/2” reducer is the challenge! 

Also - I very much do not want a 6” flue but I’m guided by the stove collar. 

[Tracy D'arth]

2 hours ago, Hoorayforboobies said:

That’s what I was thinking! 
 

trying to find 6”-4 1/2” reducer is the challenge! 

Also - I very much do not want a 6” flue but I’m guided by the stove collar. 

The reducer will be smaller than 6" because you need space for rope and Envirograf. Its not an exact science, if it fits and seals its OK.

You are overthinking the job. 

You need a reducer that will go easily into the stove top and into which will fit a 4"  or 4 1/2" flue pipe, either will fit in a 5" roof collar.

[Jen-in-Wellies]

50 minutes ago, Tracy D'arth said:

The reducer will be smaller than 6" because you need space for rope and Envirograf. Its not an exact science, if it fits and seals its OK.

You are overthinking the job. 

You need a reducer that will go easily into the stove top and into which will fit a 4"  or 4 1/2" flue pipe, either will fit in a 5" roof collar.

The rope and envirograf needs to be a reasonable thickness. Not so much that it has trouble filling the gap, but enough that it provides some compliance in the joint. The flue expands when it is hot, just as the boat expands and contracts on hot and cold days. If the flue is rigid between the stove and ceiling it can put very high stresses on the stove; enough to crack it. The flexing of the envirograf helps keep those stresses low. Another reason to use it and not rigid cement.

[blackrose]

5 hours ago, Tracy D'arth said:

Why would you want a 6" flue on a boat?

Use 4 1/2" OD pipe with a reducer in the stove collar and a 5" ID standard roof collar.  There are reducers in the chandlers.

 

I disagree, it's nothing to do with being on a boat, that's irrelevant. If the stove was designed for a 6" flue you can reduce the diameter a bit but reducing too much will affect the draw of the stove. I know because my stove has a 6" ID collar and I used to have a 4.5" flue with a reducer. If you do the maths using pi to calculate the internal flue area you'd be surprised at the % loss. I'm not saying it won't work but in my experience reducing down to 4.5" is a bit of a bodge.

 

Eventually I managed to source a 140mm dia (5.5") OD mild steel pipe and replaced the narrower one. The stove draws much better now.

 

Reduce it at the top if you have to, to get it into the roof collar but don't reduce the whole flue if you don't need to.

Edited October 6, 2023 by blackrose

[noddyboater]

8 minutes ago, blackrose said:

 

 

 

Eventually I managed to source a 140mm dia (5.5") OD mild steel pipe and replaced the narrower one. The stove draws much better now.

If anyone wants some I've got a length going spare.  140mm OD X 5mm wall thickness. Bring your own hacksaw blades though!

[blackrose]

2 hours ago, noddyboater said:

If anyone wants some I've got a length going spare.  140mm OD X 5mm wall thickness. Bring your own hacksaw blades though!

 

That's the stuff I used. It was heavy. Cut it to length with an angle grinder and a 1mm sitting disc. You'll be there for half an hour with a hacksaw.

[Machpoint005]

On 05/10/2023 at 14:06, Morris said:

Good username op, I am also a sulidae fan but alas have only had opportunity to see the gannet thus far. 

 

I recommend a trip to Shetland. 

 

And, in due course, Galapagos.