high temp sealants, and finishing the head lining around insulated flue.

[TandC]

 

Morso insulated flue kits come with an adjustable deck plate/top section of flue which drops down through the hole in the roof, allowing a bit of flexibility for fitting.   Bit like this one in the image below. 

 

The Solfitech guide referenced by BSS and citing British Standard BS 8511:2010  states that the flue as it passes through roof space should be "well protected from combustibles".

 

What does this mean for sprayfoam?  Any view on the minimum that should be removed from around the flue?  Obviously I would prefer to expose the bare minimum of roof steel - and was then going to in-fill with glass fibre.  

 

And similarly, what minimum distance from the ply ceiling panel is considered to meet "well protected"?    

 

I was planning on using a rossette collar to provide coverage over a hole cut in a larger diameter - and again infilled with rockwool. 

 

And on the outside - what sealant?   Where the flue passes through the deck plate it is loose to allow adjustability, but this must then be weather-sealed.   Presume a high temperature but also one that retains flexibility.... 

 

Any thoughts? 

 

 

[Chewbacka]

if you use a double wall insulated flue it is fairly cool, so I used a gap of about 2 inches between flue and combustible materials, but if using a single wall flue pipe it will be a lot hotter, especially if the stove should 'run away', needing a bigger clearance.

What flue are you planning on using?

As an aside I only used twin wall where it passes through the roof, the rest of the flue going down to the stove being single wall.

 

 

[TandC]

Thanks - that section in the image is twin lined and insulated.   I have the offset Morso flue kit, which contains further twin-lined flue sections for inside down to the stove and also as the external chimney.

 

However, having played around last night for the first time with the stove vaguely in place, to try and work out the hole through the roof, the whole thing looks a bit off.  The angle of offset looks a fair bit more than the tumblehome of the sides and means tilting the flue back in order to better match the side.  And this means the socket that sits over the top of the stove collar feels a bit wonky/not that securely fitted.  

 

I didn't have the clamps with me so could tighten it up - i need to have another play with it all, but i have a nasty feeling I would be better off with a length of straight flue... which is an expensive cock up as I've lost all the paperwork/box etc to the offset sections.... 

 

Maybe I will still go with a length of single-skin flue, up to the twin-walled insulated section that comes down through the ceiling.... 

 

 

 

[jonathanA]

i've no experience with twin wall flues, but 'socket that fits over the stove collar' sounds wrong, usually the flue on most stoves sits inside the collar on the top (or back). then anything nasty running back down the flue goes into the stove.   This also means you have a bit of room to play with and can put the flue slightly at an angle of slightly off centre,  sealing with fire cement or plumbaflue.   You can get different size collars for the Morso too (I think 5 and 6 inch, possibly 4 too) I know I needed a new one and you do need to be careful to get the right size for the flue you have/want to use. 

 

might be different with twin wall, where maybe the outer wall sits over the collar but the inner sits inside, don't know. 

 

also you can usually get a bit of wriggle room on the roof fitting, with the usual single wall flue cast iron roof collar.  Looking at the pic that looks different with the twin wall version and don't forget you have to allow for the slope of the roof. 

 

ETA - just re-read that the roof collar is adjustable so ignore the last bit.   🙂

Edited August 15, 2023 by jonathanA
clarity

[TandC]

15 minutes ago, jonathanA said:

i've no experience with twin wall flues, but 'socket that fits over the stove collar' sounds wrong, usually the flue on most stoves sits inside the collar on the top (or back). then anything nasty running back down the flue goes into the stove.   This also means you have a bit of room to play with and can put the flue slightly at an angle of slightly off centre,  sealing with fire cement or plumbaflue.   You can get different size collars for the Morso too (I think 5 and 6 inch, possibly 4 too) I know I needed a new one and you do need to be careful to get the right size for the flue you have/want to use. 

 

 

Thanks - i think i've either lost a bit while it's all been kicking around in the shed, or I need to find some sort of adaptor.  The collar on the stove is 5" - although measuring it the internal dimension is 5" 1/4,  and it feels from a cursory play around last night that I need an adaptor that goes INTO the stove collar, and allows the flue to then socket INTO that adaptor...  

 

From memory, when I bought it at Midland Chandlers a year ago, I was told the flue kit had everything I needed to connect to the Squirrel, but I'm not so convinced now. 

 

Only when I have that adaptor can i then work out how much adjustability there is and whether the angle can be corrected so it looks a bit more aligned to the cabin side.... hmmm.

In the absence of the instructions... this is what it says online... although that doesn't necessarily mean it doesn't still require an adaptor. 

 

The Morso flue kit is easy to assemble, and requires no cutting as the parts have telescopic connections between the flue pipes. The angle of the boat roof is taken care of by the adjustable deck plate. The system is designed to fit the standard Morso 5” collar as fitted to the Squirrel range of stoves.

 

 

[TandC]

Update - Morso technical are based in Rugby, just round the corner - incredibly helpful on the phone - all the instructions now in hand and I'm reassured I'm doing it right.  

 

If of use to anyone else in the future they're here.  

Morsø Boat Chimney Print Layout (2).pdf