Stovax Brunel 2CB stove - flue size

[geraldthehamster]

Wasn't sure whether to post this here or in General forum. I went for here.

This may be a stupid question, but can anyone help clarify what size flue pipe is required for a Stovax Brunel 2CB? The specification on the Stovax website says 5". However, the actual installation instructions (under Brunel 2CB technical information on that web page), give the diameter as 6”, with this note:

“May be reduced to 128mm (5") if burning approved smokeless fuels or burning wood in an appliance approved for use in a DEFRA smoke control area”

(in Installation Checklist, 2. Essential information) I’ll only be burning wood.

https://www.stovax.com/stove-fire/brunel-wood-multi-fuel-stoves/brunel-2cb/

https://www.stovax.com/download/Tec...l/Brunel Installation & User Instructions.pdf

However, every retailer’s website I’ve looked at repeats the 5” diameter from the Stovax web page, but also says the stove is not DEFRA approved. So I’m left a little confused.

I have a used Brunel 2CB that will be installed and properly signed off this year. Due to clearances to combustibles it will be easier to run twin wall right down to the stove. 5” is going to look less ridiculously chunky on this small stove than 6” (7” external rather than 8”)

I’ve emailed Stovax but to date have had no reply.


Cheers

Richard

 

[Doggit]

Both sites say it's a 5" outlet, but you only need twinwall going through combustible material, so you could then reduce it to an ordinary stove pipe from there. I assume the combustible material you're referring to is in the roof rather than around the stove.

 

[lostinthelight]

Both sites say it's a 5" outlet, but you only need twinwall going through combustible material, so you could then reduce it to an ordinary stove pipe from there. I assume the combustible material you're referring to is in the roof rather than around the stove.

So long as the twinwall protrudes 450mm through the combustable material before you can use single wall?.
litl

 

[geraldthehamster]

Both sites say it's a 5" outlet, but you only need twinwall going through combustible material, so you could then reduce it to an ordinary stove pipe from there. I assume the combustible material you're referring to is in the roof rather than around the stove.

Thanks.

The flat ceiling/roof is combustible, but the combustible material I'm referring to is actually some wooden paneling, that will be around a tall opening in a block-built dummy chimney breast (of which only the bottom section is yet constructed). I can't get the clearance for a vitreous enamel pipe without bringing twin wall some distance below the closure plate, so for tidiness I may as well go all the way to the stove.

Interestingly, the quotes above are from the current technical information online. The somewhat older printed instructions (dated 2004) that came with my used stove say something different again:

"must comply with Building Regulations for heat producing appliances i.e. a round flue of minimum diameter 6" (150mm) or a square brick flue of at least 5 1/2" x 5 1/2" (135 x 135mm or a factory made system manufactured to BS543 and installed to BS6461"

"... may be fitted to a 125mm (5") diameter flue if a suitable, approved liner system is installed to the manufacturers instructions with a minimum height of 4m (13')"

Which leaves me none the wiser. The final sentence says 5" is OK but refers to a liner, whereas I'm using twinwall. The overall height will be in excess of 4m

 

[lostinthelight]

5" liner or twinwall with 5" inner, same thing regarding regs.
What year was your stove built and what does the data plate say? I would be very supprised if your stove could be used with a 5" flue burning anything other than smokeless solid fuel without a manufacturers certificate to the contrary.
litl

 

[geraldthehamster]

5" liner or twinwall with 5" inner, same thing regarding regs.
What year was your stove built and what does the data plate say? I would be very supprised if your stove could be used with a 5" flue burning anything other than smokeless solid fuel without a manufacturers certificate to the contrary.
litl

Age, no idea. The installation booklet that I got with it is dated 2004. No data plate to be seen. Previous owner used a length of 5" vitreous (which I have) into a chimney. No idea how well it worked. In fact now I've looked at it again, a 6" pipe wouldn't sit inside the top outlet, on the lugs, but would have to sit outside it.

 

[geraldthehamster]

UPDATE: I've just now had this email reply from Stovax/Gazco customer service:

"As per our brochure states its 5" and this is correct."

I just hope this is a properly considered reply rather than someone just banging out a quick response

 

[Doggit]

If you have a 5" outlet, and want to use a 6" flue (which you now don't need to) then you'd use an adaptor to adjust the sizes. I think you're making this a lot more hard work than it needs to be Gerald; you're building a false chimney, so you need a twinwall liner, but that doesn't need to come down below the closure plate, so for aesthetics, you could then use a standard 5" enamel pipe. But to avoid the use of more twinwall than is necessary, I wonder if you could line the chimney with 12mm hardibacker, adn then fill it with vermiculite.

 

[geraldthehamster]

Doggit, I originally intended to use vitreous enamel pipe below the closure plate. The problem would be the clearance between the pipe and the bottom of the wooden panelling on the face of the chimney breast. This picture isn't to scale but it's not adequate.

Cheers
Richard

View media item 101115

 

[Doggit]

So what are the blocks; I assumed from your description that the whole of the upper section would be wood, but there are other options than twin wall. And for the life of me, I can't remember what the vermiculite board is called that you could line the wood paneling with is.

 

[geraldthehamster]

Constructed like this, only with a much taller (1500) and wider (1300) opening:

http://www.woodburners.com/assets/components/gallery/files/6/117.jpg

Then the whole chimney breast will be clad in wood panelling, along with the rest of the room. The problem clearance is here in red:

View media item 101116
If I use an A-rated board behind the panelling, it will need to come down some inches behind it, spoiling the appearance. I believe a 12mm gap is also required. The whole breast is only one block deep so there ain't a huge amount of space to play with.

I need to use twin wall for the first 450 down from the flat roof/ceiling in any case, because that is combustible, as are the joists.

Hopefully that reply received from Stovax settles the issue I was concerned about, anyway.

Thanks again

Richard

 

[Doggit]

But you've got blocks there, so there isn't an issue. My question is why you're using wood paneling to cover it; I'd go for either brickslips, or heat resistant plaster. I'd drop a SS liner down the pseudo chimney, and then line it with vermiculite. Yes, you need the twin wall at the top, but no more than that.

 

[lostinthelight]

UPDATE: I've just now had this email reply from Stovax/Gazco customer service:

"As per our brochure states its 5" and this is correct."

I just hope this is a properly considered reply rather than someone just banging out a quick response

Were they aware your stove could be 14 years old as stoves are modified over the years?
Aside from that, I would be very interested in the question you asked to which they made in your reply above reply .
litl

 

[lostinthelight]

As you can probably tell Richard, I am not convinced by the reply to your email.
For your own piece of mind I would either use 6" twin wall all the way which would give a much greater choice of stove if in the future you wanted a change.
or if you are determined to use use a 5" flue what about a twin wall to twin wall increasing adaptor like : https://www.flue-warehouse.co.uk/Tw...h6InchIncreasingAdaptorFromTwinWallToTwinWall
which should comply as you will have increase the size as close to the stove as practical .
I can't see a actual clearance to combustibles on installation manual, what distance do you have?
Stovax do sell smoke kits for stoves that can be converted but can find nothing relating in the parts manual
What provision are you making for flue cleaning or are you relying on removing baffles etc to sweep through the stove?
Youve read part J of the regs so am sure your aware the stove is 6kw so should require a perminant air vent?
litl

 

[geraldthehamster]

I would be very interested in the question you asked to which they made in your reply above reply .
litl

Almost verbatim what I asked here