Open-flue Gas Appliance in Compartment - Ventilation Requirements

[Rod]

We currently have an older gas boiler which is open-flue. It is in a cupboard (all right, a compartment) which has a door.

We wish to replace this door (because it is tatty). But we need to fit ventilation grilles. I *know* I found calculations for the requirements somewhere when last I looked. Now I can't. (I just find references to sites which have the information for a fee such as BSI.)

The boiler is something like 12 to 15 KW. We need to provide air inflow for combustion plus air in/out for moderating the temperature in the cupboard. (I *know* we should get a condensing boiler... :-) )

What effective area ventilation grilles are required? Or where can I find the calaculations?

[John Stumbles]

Should be in Part L of the Building Regs (see uk-d-i-y faq wiki for links) or in the bootleg BS5440-1:2000 kicking around as a torrent on th'interwub

[Andrew Gabriel]

Start by checking the boiler's installation instructions if you still have them. They override anything else.

[Rod]

Not a hope! At least two owners ago.

[Ed Sirett]

Ventilation is in BS 5440-2 - Someone very nicely made these available to the public the other year.

[Heliotrope Smith]

A compartment ventilated to a room or internal space requires 10 cm2 per kilowatt (net) of the boiler maximum rated input at high level. Low level requires 20 cm2 per kilowatt (net) You should find the rating information on the plate fixed to the boiler. Grills should be non closable and not covered in any mesh/flyscreen etc.

[Rod]

Thanks all. I couldn't get any torrents to start d/l. :-(

[PCPaul]

My boilers installation and user manuals were on their web site (vokera)

- you could try that?

[geoff]

What appliance is it ?

There's an outside chance I will have the manual for it

... or can lay my hands on one

[Rod]

IIRC Poxi-Batterton Kingfisher? - maybe Kingfisher 2 or something. Cupboard is dark so do not wish to look right now. :-)

[John Stumbles]

There's also a torrent of boiler manuals. Try googling 'GAM torrent' for starters. You can select which files you download from the almost 2 gigs total size of the torrent.

[geoff]

You might be in luck there

ring me tomorrow

01923 229224

[Ed Sirett]

That will be a slight over estimate. Pretty much all appliances are quoted in gross. So 9 and 18 are the figures. Also the combustion air supply is required to the room containing the compartment. This is 4.5cm2/ kW (from outside air), but the first 7kW are discounted.

[Heliotrope Smith]

Not an estimate, but the figures stated in the regulations. I did add in my post that the figures are net so of course divide 1.11 if input is stated gross to give the required size of vents. You are a little out of date with combustion air supply sizing. This has been 5cm2 per kW (-7kW) for some time now.

[Rod]

Sorry - didn't manage to call but thanks for offering.

[John Stumbles]

which, funnily enough, gets you to 4.5 cm^2

[Rod]

That bit is already sorted. Thanks for pointing it out though.

[Heliotrope Smith]

You're right. Too much red stuff, should have realised ED was talking in old money.

[Ed Sirett]

Which still seems to be the currency. Almost no gas appliance I've seen in the last few years new or old uses the 'new' money.