Problem with flue

[DannyC]

Hi everyone,

 

I have an issue with my flue which (hopefully) you can see in the video. Any idea how to fix this? Thanks :)

[Jen-in-Wellies]

Sorry, can't tell what is wrong from the video. Can you describe?

Jen

[Tony Brooks]

I can't see much in the video, lets have photos that we can enhance if required AND a description of the problem

[DannyC]

Ok so thhe point where the flue starts to join the burner has come lose. So if you hold the main unit you can wiggle it. Essentially the seal appears to have broken. You can see where it glistens in the light in the picture. 

 

Sorry - a difficult one to explain!

[Tony Brooks]

 

So assuming the problem is at the joint arrowed

 

Typically the flue pipe slides into a casting that fits to the top or back of the stove but in this case it looks as if there may be an adaptor between the two. Typically the gap between the flue pipe and stove boss would be packed with glass fibre rope and then topped off by high temperature silicon or in older boats fire cement.

 

It is not clear to me if the stepped  "pipe" below that joint is part of the stove or as I said an adapter It might even be a socket that was part of the pipe.  If so then something has broken.

 

The gap that shines does not look large enough to hold any glass fibre rope so I suspect you may have to lift the pipe up through the roof collar, clean off the rust on the pipe and in the socket and then  refit with plenty of high temperature silicon.

 

I await with interest others' take on this.

 

[Higgs]

54 minutes ago, DannyC said:

Ok so thhe point where the flue starts to join the burner has come lose. So if you hold the main unit you can wiggle it. Essentially the seal appears to have broken. You can see where it glistens in the light in the picture. 

 

Sorry - a difficult one to explain!

 

 

I notice that you can wriggle the flue. You shouldn't really be able to do that, even with the sealant shot. Also, the flue should fit securely (firmly) at the fitting, going through the roof: I prefer high temperature silicon and heat bandage - not cement. The flue at the place where it sits in the stove collar should be inspected for rot in the steel. The flue should be firmly seated in the stove collar, yours isn't. I'd lift the flue and check it at its base. My preference for sealant is high temperature silicon, even at the stove collar, and I would run a bead of sealant at the join you are pointing out, smoothing into the join. 

 

All use of silicon is to allow for movement during heat expansion, avoiding too much pressure being placed on the top plate of the fire, especially in cast iron stoves. Most of the movement (not so much movement, but give) will be allowed at the roof, going through the collar fitting. 

 

 

Edited August 9, 2020 by Higgs

[Alan de Enfield]

24 minutes ago, DannyC said:

So if you hold the main unit you can wiggle it.

Does this mean that the fire itself can be moved/wiggled, or the flue can be moved ?

[blackrose]

If you're going to use high temp silicone down at the stove end of the flu then use something like Envirograf which can handle temps of up to 1200C, not Plumbaflu which only goes up to 300C and may break down after some time at that temperature.

 

Envirograf comes in black and is only a few quid more. Plumbaflu is fine for the top end of the flu but not really for the much hotter stove end.

Edited August 9, 2020 by blackrose

[DannyC]

3 hours ago, Alan de Enfield said:

Does this mean that the fire itself can be moved/wiggled, or the flue can be moved ?

The flue is what's moving.

 

Thanks for the advice.

 

It appears there was some kind of sealant there that has now perished. I will follow the advice of checking for rot in the seal and a high temperature sealent. All is fine at the roof end as far as I can see.

 

 

[Richard10002]

3 hours ago, blackrose said:

If you're going to use high temp silicone down at the stove end of the flu then use something like Envirograf which can handle temps of up to 1200C, not Plumbaflu which only goes up to 300C and may break down after some time at that temperature.

 

Envirograf comes in black and is only a few quid more. Plumbaflu is fine for the top end of the flu but not really for the much hotter stove end.

I second Envirograf as a heat resistant sealant... however, you need to leave it for a few days to cure

 

AND

 

before you first light the fire after using Envirograf, open all windows and doors, and get everyone, including the dog, out of the boat - until the smokey fumes given off by the sealant have stopped and cleared........

 

Ask me how I know this  

[DannyC]

Ok great. Will keep this in mind!

[bizzard]

If the flue pipe moves it's very likely to have let go at the top too. Fluepipes rust and corrode from the top downwards, shortening it all the time. Poke around at the top of the pipe inside the boat to see if corrosion is present and pin holes, if so renew it.

[pete.i]

That looks like an adapter and whoever fitted it has left the four inch (assuming that is the diameter of the flue pipe) and just sat the flue pipe on top. this would have meant a microscopic amount of sealer would have been used and now that sealer has broken down. If the adapter had been cut down to the next step and the flue pipe then fitted there would have been enough gap to wedge in the fire rope and a good squeeze of high temperature silicon on top. Obviosly that cannot be done as the flue pipe is too short.

[Jen-in-Wellies]

1 minute ago, bizzard said:

If the flue pipe moves it's very likely to have let go at the top too. Fluepipes rust and corrode from the top downwards, shortening it all the time. Poke around at the top of the pipe inside the boat to see if corrosion is present and pin holes, if so renew it.

This ^^^^. I reckon around five or six years for a bog standard Midland SwinChandlers flue pipe in live aboard use. If it was installed many years ago it is probably like lacy tissue paper at the top where it goes through the roof collar. 

Jen