Flu collar (external)

[Zoeb]

Hi

 

We are installing a straight flue onto our squirrel stove. It sits on the port side, so How do you get over the outside collar sitting at an angle on the roof without getting your flue bent slightly?

 

I have seen some boats with little hardwood wedges but can't understand the logistics of making this watertight / secure etc !

 

Does anyone have any instructions/ tips / photos of their installation?

 

Help!

 

Z

[Iain_S]

We had a problem with a "rocky" collar on Copperkins. The problem was that the collar was secured fore and aft, and had a flat base, which sat on a convex curved roof, It didn't really get fixed for some time, and only really got done when the roof needed a bit of reinforcement .

 

My thoughts were that if a shaped metal bar was put under the collar on the lower (outer) side, that would allow the securing bolts to hold the collar firmly, and that bedding the whole thing down in sealant would have made it waterproof. The inserted bar wouldn't have needed to be shaped accurately, as the gaps could be filled with sealant either during or after fitting.

 

The joint between the collar and flue should, especially with a straight flue, be sliding, to prevent excess pressure on the stove top when the stove expands when heated. (Got the T shirt for that as well!) Usual method is fibreglass rope or tape around the flue, and a bead of silicon around the top to seal it. That joint doesn't need to be fully waterproof, so long as the collar is capped when the stove isn't in use.

[Zoeb]

We had a problem with a "rocky" collar on Copperkins. The problem was that the collar was secured fore and aft, and had a flat base, which sat on a convex curved roof, It didn't really get fixed for some time, and only really got done when the roof needed a bit of reinforcement .

 

My thoughts were that if a shaped metal bar was put under the collar on the lower (outer) side, that would allow the securing bolts to hold the collar firmly, and that bedding the whole thing down in sealant would have made it waterproof. The inserted bar wouldn't have needed to be shaped accurately, as the gaps could be filled with sealant either during or after fitting.

 

The joint between the collar and flue should, especially with a straight flue, be sliding, to prevent excess pressure on the stove top when the stove expands when heated. (Got the T shirt for that as well!) Usual method is fibreglass rope or tape around the flue, and a bead of silicon around the top to seal it. That joint doesn't need to be fully waterproof, so long as the collar is capped when the stove isn't in use.

 

thanks Iain. I think I can make this work on the roof - using various things and also some sealant.

 

In relation to your last point about the joint between the collar and flue being sliding... I have been told this previously too, and it all makes sense, but how far down should I sit the pipe into the collar on the top of the stove? Maybe 5mm above the top of stove? This sounds tricky! Presumably both actions (roping the top and the bottom of the flue) need to be done simultaneously...?

[nbfiresprite]

Uxbridge boat centre sell a hardwood mounting for collar to seat on a curved roof.To fit run two beads of heatproof sealant on the under side of the mounting, one along the outside edge and fix the collar on top and tighten the bolts, once done remove the excess sealant. My own has been in place since 2010 without a leak.

[Iain_S]

 

(snip) ... but how far down should I sit the pipe into the collar on the top of the stove? Maybe 5mm above the top of stove? This sounds tricky! Presumably both actions (roping the top and the bottom of the flue) need to be done simultaneously...?

 

I'm not an expert on stove installation, but in our case, the flue sat on top of fibreglass rope in the stove socket. The gap at the top of the socket was filled with fire cement, later replaced with high temperature silicon. The stove top took the weight of the flue.

[ROBDEN]

About eight years ago I fitted a stove into my last boat. The collar I bought was built-up one side to allow for the curve.

I think they had three sizes with different amounts of build-up for different curves.

Can't remember the name but it was a large chandlers near London.

 

Rob....

[Neil Smith]

I have also seen angled flue collars, it could have been limekiln chandlery.

 

Neil

[ROBDEN]

Re; post 6.

Just been told it was Uxbridge.

 

Rob....

[trackman]

We have an angled collar on ours that keeps the chimney vertical on the curved roof. It will have come from Midland Chandlers as that's where our builder gets his bits.

 

As already said, the flue should not be rigidly fixed in the collar. If it is, expansion in the heat will cause it to damage something, most likely your expensive stove!

 

It should be packed to centre it in the collar with glass fibre rope and high temp silicon seal should be applied over the rope to seal flue to collar.

 

To stop tarry condensate on your roof use a lined chimney & insulate the chimney liner with high temp spray foam or glass wool. Ensure that the liner extends down inside the top of the flue when the chimney is in place on the collar. Do not use a "coolie hat" when the stove is lit. If you do tarry stuff will condense on its underside and drip onto the roof, nicely undoing all the precautions described!

[Richard10002]

We made a "sloping" wooden insert the same shape as the collar, positioned it with plenty of high temp sealant, (Plumba??), and sealed the edges.

 

Needed a bit of thinking about to get the angles right, but with a Black and Decker workbench, a good saw, and a sharp plane, it was relatively straightforward.