Have decided a combi is the way to go and am going to install it in an
existing 'larder' cupboard in the kitchen.

Unfortunately, the plastic soil stack for the house runs down the back
of the cupboard.

As the walls of the cupboard are brick, I'm thinking maybe I'll make a
false back to the cupboard out of thick plywood, attached to the side
walls using battens. I'd then mount the boiler directly to the
plywood. The flue can go through the plywood to one side of the soil
stack and exit through the brickwork in the normal way.

Is there any reason not to do this? 

sponix

On Sun, 28 Aug 2005 14:02:57 +0100, --s-p-o-n-i-x-- 
wrote:


>Have decided a combi is the way to go and am going to install it in an
>existing 'larder' cupboard in the kitchen.
>
>Unfortunately, the plastic soil stack for the house runs down the back
>of the cupboard.
>
>As the walls of the cupboard are brick, I'm thinking maybe I'll make a
>false back to the cupboard out of thick plywood, attached to the side
>walls using battens. I'd then mount the boiler directly to the
>plywood. The flue can go through the plywood to one side of the soil
>stack and exit through the brickwork in the normal way.
>
>Is there any reason not to do this? 
>
>sponix


I would be very carefull in making sure you can mount the boiler on a
combustable surface, I think you can't do this.

Rick

On Sun, 28 Aug 2005 14:29:08 GMT, Rick  wrote:


>I would be very carefull in making sure you can mount the boiler on a
>combustable surface, I think you can't do this.


That's the sort of thing that worries me. Does anyone know for sure?

What constitutes a combustible surface? Does it mean you can't mount
it on a wallpapered wall?

sponix

On Sun, 28 Aug 2005 17:48:17 +0100, --s-p-o-n-i-x-- 
wrote:


>On Sun, 28 Aug 2005 14:29:08 GMT, Rick  wrote:
>
>>I would be very carefull in making sure you can mount the boiler on a
>>combustable surface, I think you can't do this.
>
>That's the sort of thing that worries me. Does anyone know for sure?
>
>What constitutes a combustible surface? Does it mean you can't mount
>it on a wallpapered wall?
>
>sponix



You could use a wallpapered wall but plywood would not be a
non-combustible surface.

However, you do need the strength, so you couldn't just use
plasterboard on its own either without a suitable frame behind.  A
typical boiler weighs in the region of 30-40kg.

I would make a timber frame and if the width is much wider than 600mm,
put in additional framing timbers, obviously avoiding the flue
position.   Fit additional horizontal timbers such that the fixing
holes for the boiler (some kind of bracket is typical)  end up going
into timber.

You could take advantage of the void behind the panel to run pipes and
cables.  However, if this is done, it might be a good idea to make the
panel in two sections.  The one taking the boiler would be fixed
permanently, and then one  removable one below or possibly the side
depending on the pipe routing.

You can use a fireproof board like Masterboard or Knauf  to make the
non combustible surface.


-- 

..andy

To email, substitute .nospam with .gl

On Sun, 28 Aug 2005 19:50:27 +0100, Andy Hall <andyh@hall.nospam>
wrote:


>You can use a fireproof board like Masterboard or Knauf  to make the
>non combustible surface.


Does it *have* to be non combustible? I have seem conflicting info on
this? 

If it does have to be non combustible, why is it OK to have wallpaper
(which is in itself combustible) behind?

sponix

On Sun, 28 Aug 2005 20:44:41 +0100, --s-p-o-n-i-x-- 
wrote:


>On Sun, 28 Aug 2005 19:50:27 +0100, Andy Hall <andyh@hall.nospam>
>wrote:
>
>>You can use a fireproof board like Masterboard or Knauf  to make the
>>non combustible surface.
>
>Does it *have* to be non combustible? I have seem conflicting info on
>this? 
>
>If it does have to be non combustible, why is it OK to have wallpaper
>(which is in itself combustible) behind?
>


Wallpaper pasted onto a plaster surface won't support combustion on
account of it being intimately attached to the much greater mass of
the plaster wall (which is intrinsically non-combustible) which keeps
it's temperature more or less at the ambient temp. of the interior of
the boiler cupboard.

There will be a standard test for this.

DG

On Sun, 28 Aug 2005 20:44:41 +0100, --s-p-o-n-i-x-- 
wrote:


>On Sun, 28 Aug 2005 19:50:27 +0100, Andy Hall <andyh@hall.nospam>
>wrote:
>
>>You can use a fireproof board like Masterboard or Knauf  to make the
>>non combustible surface.
>
>Does it *have* to be non combustible? I have seem conflicting info on
>this? 
>
>If it does have to be non combustible, why is it OK to have wallpaper
>(which is in itself combustible) behind?
>
>sponix



AIUI, the issue is the extent to which the material supports and
transmits flame.

As far as whether you *have* to use a non-combustible surface is
concerned, I always have done because it's an added degree of safety
which costs very little.   In fact, I have always lined enclosures for
boilers with fireproof board on all surfaces.

There is a reference to all of this in part J of the Building
Regulations (section on gas burning appliances.)

They do also say that one can follow the boiler manufacturer's
instructions.    You may find that with some, the manufacturer says
that it isn't necessary to take precautions about non-flammability
because the case temperature is low.	The same issues relate to
compartment ventilation.

Either way, I do think that it's important to have a very substantial
fixing, and I wouldn't trust 18mm ply to do that on its own - i.e. I
think that studs behind are important.   Given that situation, there
doesn't seem to be any value in using ply vs. using plasterboard.





-- 

..andy

To email, substitute .nospam with .gl

--s-p-o-n-i-x-- wrote:


> As the walls of the cupboard are brick, I'm thinking maybe I'll make a
> false back to the cupboard out of thick plywood, attached to the side
> walls using battens. I'd then mount the boiler directly to the
> plywood. The flue can go through the plywood to one side of the soil
> stack and exit through the brickwork in the normal way.
> 
> Is there any reason not to do this? 


I assume tyou mean the soil pipe runs inside the cupboard stopping you 
finding enough blank back wall to hang the boler (i.e. not on the 
outside wall adjacent to the cupboard)

Perhaps my mental picture is wrong, but given that most boilers these 
days have the flue emerge out of the top of the case at a rotatable 
turret. Could you not mount the boiler on the side wall of the cupboard 
and then take the flue sideways out of the back wall to the side of the 
soil stack.

Failing that get a pipe standaoff for the boiler and pack the mounting 
plates out far enough such that it stands over the soil pipe.


-- 
Cheers,

John.

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