fitting new flue to old flue

[Peteonthelee]

Any tips??? am attempting to fit a new stove - I have kept the old part of flue going through the roof and am looking to attach a new flue to the old part left inside the boat. Has anyone done this before? The main issue I have I think is matching the right diameter of old flue to the new. I was looking to put some cementone where the flues attach as well as a brace (jubilee clip thing) around the two to hold together.

 

 

[rusty69]

Doesn't answer your question, but unless you are confident the flue pipe passing through the roof collar is in good condition (usually a prime failure point), I would put a new piece in whilst fitting the stove .Preferably a welded or single one piece straight pipe, assuming its a standard steel narrowboat type install.

Edited October 24, 2018 by rusty69

[Old Son]

DO NOT butt joint the flue pipes and hope a jubilee clip will hold it together.

[Jen-in-Wellies]

25 minutes ago, Peteonthelee said:

Any tips??? am attempting to fit a new stove - I have kept the old part of flue going through the roof and am looking to attach a new flue to the old part left inside the boat. Has anyone done this before? The main issue I have I think is matching the right diameter of old flue to the new. I was looking to put some cementone where the flues attach as well as a brace (jubilee clip thing) around the two to hold together.

 

 

Any chance of a picture of the stove and the bit where the flue goes through the roof? I am wondering if what you are calling the old part of flue going through the roof is what everyone else calls the flue collar.

Jen

[rusty69]

2 minutes ago, Jen-in-Wellies said:

Any chance of a picture of the stove and the bit where the flue goes through the roof? I am wondering if what you are calling the old part of flue going through the roof is what everyone else calls the flue collar.

Jen

Ah, yes could be the deck/roof collar OP has kept, not the flue pipe as I assumed.

[Peteonthelee]

Hi - no pic at present but there is about 30cm of flue pipe coming into the boat itself so not the collar (I don't think). 

[dmr]

You should have a flue collar fixed to the roof, usually cast iron, sometimes aluminum. If done proper the steel flue should pass through this without touching it, spaced with stove rope and  maybe some sealant. If there is contact then sometimes they rust together. You need to get the remnants of the old fluepipe out and then fit a new one. It might well need a welder to put a couple of bends in it so that it lines up correctly with both stove and collar. This is a very routine job on the cut.

 

A few boaters, usually DIY "do it as cheap as possible" types do weld the flue pipe directly to and through the roof. This is a real botch. If you have this then you really need to cut it all out and start again with a proper flue collar. CO from stove fumes can kill you, your friends and family and your dogs and cats.

 

This is a flue collar

 

https://www.ebay.co.uk/i/272443450969?chn=ps

 

...............Dave

[Sea Dog]

The chimney is supposed to lift off a collar on the roof which forms the roof warertight seal and attaches the internal flue with a gas tight seal.  If you bodge a permanent chimney onto something previously fitted that you're unsure of, how are you going to:  1. guarantee those crucial seals, and 2. remove the chimney when you need to get under something low whilst navigating? 

 

There is some stuff you can probably bodge on a boat (not on my boat, I hasten to add!), but flue gas and roof seals are two of the things that could really bite you in the bum if you do.

[dmr]

And, the flue pipe should not be captive in the collar or roof as this can transmit various forces directly to the top of the stove (thermal expansion, you walking on the roof) and it is said that this could crack the top of a cast iron stove. We had a bodged up flue for a number of years and I just felt so much happier when I did it all properly.

 

..............Dave

[Peteonthelee]

Thank you all for that input - I am going to knock out the existing bit of flue going up to the collar and see the condition of it all -Hopefully it will be a relatively simple case of replacing the flue and then sealing properly as some have advised

 

[rusty69]

6 minutes ago, Peteonthelee said:

Thank you all for that input - I am going to knock out the existing bit of flue going up to the collar and see the condition of it all -Hopefully it will be a relatively simple case of replacing the flue and then sealing properly as some have advised

 

Don't be Cross, it's the best course of action

[rusty69]

On a more serious note,It will be much easier removing the flue "stub" than a whole flue pipe as you can wiggle it.....just a little bit.

 

Some of mine have been so difficult to extract over the years whilst connected to the stove and I have ended up cutting them in half to get some wiggle room.

Edited October 26, 2018 by rusty69

[Cheshire cat]

This is what my flue pipe looked like. The corroded bit was up inside the collar. It had been on the bank a couple of weeks when I took the photograph but you get the idea. I would recommend having a look. The good bit was 4mm wall thickness.

[Peteonthelee]

Took the flue pipe out - after a very little wiggle I have to say. So looks a simple case of putting in flue to collar - there is a moderate amount of rust in the collar. I thought I would scrape this out and then maybe put some sort of sealant/adhesive where the flue runs into the collar - there does not seem to be space between the collar and a 5 inch flue as the old flue was tight in (going back to Dave's point about not being captive in the collar - not sure this is avoidable)

 

Pete