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Flu leaking into boat

Karl

By Karl
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Karl Contributor

Karl

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Hi all. I’ve had this problem before and thought I had cured it after taking advice form all sorts of places. The problem is when we have our stove on with coal or logs but mainly coal we get a run inside the boat that runs down the outside of the flu and takes the paint off the top of the stove it’s so hot. Apparently it’s condensation spilling over the collar and back down into the seal between the collar and the flu.it bloody stinks aswell and makes us feel sick. Last time I took the flu out of the boat. Cleaned all the surfaces and used 2 inch wide fire bandage so it was snug enough to just push the flu down into the boat. Made sure non of the bandage got snagged then put fire sealant on top. Then used some fire rope on top of that the covered that with about an inch of the same black fire sealant. 

Three weeks later and it’s started all over again. There are no cracks in the cast or the flu. I just can’t work out how after a few weeks the hot condensation and tar from the coal eventually get through. So much so that when I go to remove the fire sealant to replace it there is not much effort required to get the old stuff out. I’ve got the surfaces as clean as I can and it still doesn’t work. What am I doing wrong ? Would I just be better taking everything out and replace the whole joint with fire cement or is that the wrong thing to do ? It’s driving me mad. This will be the fourth attempt ! Thanks all.

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Karl Contributor

Karl

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Sorry, an inch deep not wide. The gap between the collar and the flu is probably half an inch all the way round. Maybe slightly less but just a guess. I have tried 12 mm fire rope but that doesn’t fill the gap so I have to pack as much in as I can and double it up. It’s a 4.5 inch flu pipe and I suspect a 5 inch collar. The sealant is black silicone fire sealant like they use on sealing flu pipes etc and heat resistant to over 800 degrees.

1 minute ago, matty40s said:

Better than Covid19 getting in.

 

2 minutes ago, matty40s said:

Better than Covid19 getting in.

Really helpful !

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matty40s Veteran II

matty40s

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Are you sure the condensation and black sludge isnt getting in through either the 2 collar bolts or between the roof and collar??

If you have a coolie hat and run your stove 24/7, the amount of condensation and black sludge is massive, especially if you are burning damp or unseasoned wood.

Hope this is more help.

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dmr Veteran II

dmr

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A twin walled chimney should help enormously, but not a 100% guaranteed fix.

How big is the gap between flue and collar? I prefer a suitably thick length of fire rope to bandage, thick stuff is available, get a selection and use one that is really tight poked in with a blunt screwdriver. In my case this has proved adequate for years so I don't even use a sealant.

Does the flue sit flush or proud of the collar, or is it significantly recessed?

A good start would be to take the chimney off and have a good look and maybe you will see where the failure is.

 

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

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29 minutes ago, Karl said:

Hi all. I’ve had this problem before and thought I had cured it after taking advice form all sorts of places. The problem is when we have our stove on with coal or logs but mainly coal we get a run inside the boat that runs down the outside of the flu and takes the paint off the top of the stove it’s so hot. Apparently it’s condensation spilling over the collar and back down into the seal between the collar and the flu.it bloody stinks aswell and makes us feel sick. Last time I took the flu out of the boat. Cleaned all the surfaces and used 2 inch wide fire bandage so it was snug enough to just push the flu down into the boat. Made sure non of the bandage got snagged then put fire sealant on top. Then used some fire rope on top of that the covered that with about an inch of the same black fire sealant. 

Three weeks later and it’s started all over again. There are no cracks in the cast or the flu. I just can’t work out how after a few weeks the hot condensation and tar from the coal eventually get through. So much so that when I go to remove the fire sealant to replace it there is not much effort required to get the old stuff out. I’ve got the surfaces as clean as I can and it still doesn’t work. What am I doing wrong ? Would I just be better taking everything out and replace the whole joint with fire cement or is that the wrong thing to do ? It’s driving me mad. This will be the fourth attempt ! Thanks all.

Is the collar 100% sealed to the roof?

 

We used to get runs down the outside of our flue. It looked sealed on a cursory inspection but it definitely wasnt.

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dmr Veteran II

dmr

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Crossed posts a bit.

Fire rope is available up to at least 25mm so get some thick stuff. It needs to be tight else it might slowly work downwards with expansion/contraction movement. Even so it might need adjusting a few times each year.

Pictures looking down from above would be good.

We have a twin walled chimney, run the stove 24/7 at present, and the rope will be a bit brown and grubby but otherwise dry and free from gunge. I like the flue to sit flush or better slightly proud of the collar but I believe this is another pumpout/cassette thing ?

 

It's possible that your small flue in a big collar is giving a mismatch with the inner skin of the chimney?.

 

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

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Tony Brooks Veteran II

Tony BrooksDonate to Canal World

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We are talking double skin chimney, not a double skin flue.

 

The chimney inner can often be repositions and adjusted so it sits inside the top of the flue and the if you fill the void with expanding foam it will help keep the inner flue hot and thus minimise condensation. any condensation that does form will drip down the flue.

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matty40s Veteran II

matty40s

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9 minutes ago, The Happy Nomad said:

Is the collar 100% sealed to the roof?

 

We used to get runs down the outside of our flue. It looked sealed on a cursory inspection but it definitely wasnt.

There was very little sealant and a lot of rust under your old collar, nobody since you had bothered to sort out the leaks inside either.

 

20210112_211904.jpg

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matty40s Veteran II

matty40s

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7 minutes ago, Tony Brooks said:

It looks to me as if the flue is too short. In my view the top of the flue should be just about level or slightly proud of the top of the collar. The step where it ends will make an ideal gunk trap.

It was, assisted by the coolie hat.

20210112_213020.jpg

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dmr Veteran II

dmr

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2 minutes ago, Tracy D'arth said:

Desperately in need of scraping and sweeping which won't help your gunge problem.  What are you burning?

My wife tells me that a long long time ago she found a pile of coal at the side of the road so took it home and put it on the open fire. She then discovered that it was in fact lumps of tar. That's what the OP is burning. ?

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matty40s Veteran II

matty40s

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5 minutes ago, TheBiscuits said:

@matty40s seems to have confused everyone now by posting pictures of another boat (The Doghouse) in general conversation.  These pics aren't from the OP who is asking for advice ...

I'm glad someone is paying attention.

It has a brand new flue now and strict instructions about non coolie hat use.

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3 minutes ago, TheBiscuits said:

@matty40s seems to have confused everyone now by posting pictures of another boat (The Doghouse) in general conversation.  These pics aren't from the OP who is asking for advice ...

It is indeed our old boat but I'm unsure as to when the pictures were taken. I know the collar was resealed at Rugby boats when it was put on sale in 2015. We had also done it the previous year.

 

But on niether occasion was the collar removed AFAIK. 

 

 

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matty40s Veteran II

matty40s

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1 minute ago, The Happy Nomad said:

It is indeed our old boat but I'm unsure as to when the pictures were taken. I know the collar was resealed at Rugby boats when it was put on sale in 2015. We had also done it the previous year.

 

But on niether occasion was the collar removed AFAIK. 

 

 

You cant reseal a collar properly without removing it, and the underlying rust first. 

Running a new bead of silicon round the edge just to make it look tidy might last 12 months before the underlying problems come back.

Edited by matty40s
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Bee Veteran

Bee

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F********** hell, that needs cleaning!!!! You really need to sort that but you will still have that horrible stuff coming in the boat. You might find that some ingenuity, fire cement, fire rope and a conical section of a stainless steel funnel / tundish will divert the tar away from the joint that is giving trouble but don't narrow the chimney. Damp wood will produce a hell of a lot of tar that is bad for lungs and smells horrible .

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5 minutes ago, matty40s said:

You cant reseal a collar properly without removing it, and the underlying rust first.

That was what was done at the time. I dont know who did the work for them, or if they did it themselves.

 

I know all I paid for was for the collar to be resealed. Along with new batteries.

Edited by The Happy Nomad
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