Supporting stove flue while installing - how to do?

[That Johnny]

Hi everyone,

 

Apologies if this has already been answered elsewhere, I did some searches and couldn't find it.

 

I have had to remove the old 4.5" single-wall flue pipe from my Morso 1430 stove. It came out the top of the stove via the standard Morso collar and a reducing adapter, then exited the boat through a common-or-garden twin-coach-bolt roof collar. It was just a straight length of tube, no angles/bends, but mitred slightly at each end to allow for the slight offset of the stove from the roof collar.

 

My question is, if the stove is not supposed to bear the weight of the new flue (which is pretty heavy in my opinion), how am I going to install it? Does it "hang" from the roof collar?

 

And if so, is the proper way to install it going to be "me standing there holding it slightly above the stove top plate until the cement/sealant in the roof collar has hardened and glued the flue in place"?

 

Seems a bit silly to me, but I haven't been able to think of a better solution. I'm sure someone knows the right way to do this though

 

My only other thought was to put a good amount of fire rope underneath the Morso collar on top of the stove (I had to remove a thick layer of old rope from there, which was squashed pretty flat). Then the flue could rest on the rope and hopefully the "give"/"compression" of the rope will take up the expansion of the flue & stove when the fire is lit?

Sorry if this is a stupid question, but I am stumped! And getting increasingly chilly at night, uh oh...

[dor]

You could support the flue in the stove collar with some bits of wood. These will burn away when the stove is lit.

i fit the flue so it is floating in the stove collar, then use some fire rope to centre it then use HT silicone to seal.

[That Johnny]

Thanks! That's an interesting idea. What sort of thickness of wood do you use? I'm guessing a few millimetres thick, 1/8" kind of thing? 

[Tony Brooks]

I suspect the thing about not letting the flue sit on the stove top is because if it is fixed in the roof adapter it will expand and apply force to the stove top. If you do as Dor says and also at the roof collar the silicon will allow the flue to expand and push up through the collar. Mine did this every time the stove was lit.

[Jen-in-Wellies]

18 minutes ago, dor said:

You could support the flue in the stove collar with some bits of wood. These will burn away when the stove is lit.

i fit the flue so it is floating in the stove collar, then use some fire rope to centre it then use HT silicone to seal.

I've done this. Was able to remove the bits of wood from inside after the roof collar flexible silicone sealant had set, but burning them away was the original intention and I can't see why it shouldn't work. Even bits of paper, folded up to give a suitable thickness would work.

Jen

Edited September 28, 2020 by Jen-in-Wellies

[That Johnny]

This is great, thanks so much everyone. I will try the bits-of-wood-or-paper idea and see how I get on, much appreciated

[dor]

12 minutes ago, Johnny Darifi said:

This is great, thanks so much everyone. I will try the bits-of-wood-or-paper idea and see how I get on, much appreciated

A few mm is fine.  The flue will drop a bit, but as long as it can move a bit in the roof collar it should be ok.

 If it is too rigid it can crack the stove top or collar when it expands.

[OldGoat]

Echo most of the above.

My stove pipe is made from 1/4" pipe that my local blacksmith had knocking about (local blackies are jolly useful) and (because I hate flue pipes that run at a 'funny angle'), I have two 135 degree joints to keep the system inline (if you see what I mean. Both ends of the pipes are free to move in the collars.

It "weighs a ton"

Been like that for 20 years on the water and nothing's broken (yet)...

[BWM]

You said that the flue is chamfered to allow for a slight misalignment, normally this causes the top join to leak. If it did, it would be useful to straighten the flue. 

[DHutch]

1 hour ago, OldGoat said:

Both ends of the pipes are free to move in the collars.

 

What holds it then? And how does it seal?

3 hours ago, Johnny Darifi said:

 

My question is, if the stove is not supposed to bear the weight of the new flue (which is pretty heavy in my opinion), how am I going to install it? Does it "hang" from the roof collar?

 

It is a very good question.

 

Ours (cast iron drain pipe, with 135 dogleg, squirrel) is held together with high temp silicone and glass rope, and rests on the stove top. The top end is sealed with silicon but has flexibility to move. I understand it was a right PITA to hold it all in place while it cured.

 

Previously it was the same but with fire cement, which was fine till moisture got in, frooze, and split a 135. Or at least that is out diagnosis for why it broke one winter.

 

 

Daniel

[OldGoat]

2 minutes ago, DHutch said:

What holds it then? And how does it seal?

Two retaining screws on the bends and fire rope (whatever it's called ) at the top and bottom

[GUMPY]

I have always mounted the flue into the stove solidly with fire cement and the roof collar with rope and HT sealant, not had a problem in 30 years and 3 boats. Today I have just redone the top of the flue on Loddon as the collar had to come off as part of the repaint.

[Ex Brummie]

Bed the flue on ceramic rope in the collar on the fire. seal with fire cement. Pass the pipe through the roof collar, pad it out with ceramic rope ensuring there is no metal to metal contact. Seal the top with HT silicon. When the fire is lit, expansion will be taken up by the movement through the collar. If you allow metal to  metal contact in the roof collar, then it will rust fuse and split the top of your stove. Silicon in the collar will not hold the flue pipe in suspension.

[ditchcrawler]

3 hours ago, DHutch said:

What holds it then? And how does it seal?

It is a very good question.

 

Ours (cast iron drain pipe, with 135 dogleg, squirrel) is held together with high temp silicone and glass rope, and rests on the stove top. The top end is sealed with silicon but has flexibility to move. I understand it was a right PITA to hold it all in place while it cured.

 

Previously it was the same but with fire cement, which was fine till moisture got in, frooze, and split a 135. Or at least that is out diagnosis for why it broke one winter.

 

 

Daniel

Passed the boat today, you need a new chimney on the top of her.

Edited September 28, 2020 by ditchcrawler

[DHutch]

14 minutes ago, ditchcrawler said:

Passed the boat today, you need a new chimney on the top of her.

That is the new(ly painted) chimney funnel on her! Just needs the final coat of flat-black and half the dents will disappear, it does look rather battered in ali epoxy mind!

 

 

The stove is the little one forward of the main flue.

 

 

Daniel

[ditchcrawler]

1 hour ago, DHutch said:

That is the new(ly painted) chimney funnel on her! Just needs the final coat of flat-black and half the dents will disappear, it does look rather battered in ali epoxy mind!

 

 

The stove is the little one forward of the main flue.

 

 

Daniel

I thought there were blast holes near the top, Boat looked fine by the way when we passed today, didnt stop.

[DHutch]

15 hours ago, ditchcrawler said:

I thought there were blast holes near the top, Boat looked fine by the way when we passed today, didnt stop.

There is a patch which has rotted due to dissimilar metal corrosion behind the brass band. However once we reinstate the brass band (which has also had a coat of alu epoxy on the back face) then they will be covered up again!

 

Truth be told, we might be due another funnel (outer) eventually, however this one has done 30 years and still holds flue gasses just fine. The inner skin which actaully does all the work is stainless and not going anywhere fast.  

 

Daniel

[dor]

Will the brass band be performing a concert anywhere?

[David Mack]

1 hour ago, dor said:

Will the brass band be performing a concert anywhere?

 

My wife's brass band hasn't been allowed to rehearse since about April, let alone perform.