Ask The Trades - Vents in cupboard containing boiler

Welcome, Guest. Please Login or Register

	Jun 15^th, 2026, 3:07pm
View recently thanked users View top thanked users

Quote: The early bird may get the worm, but the second mouse gets the cheese.

Ask The Trades › DIY Forum › Plumbing Questions › Vents in cupboard containing boiler

(Moderator: thescruff) - (Moderator Group: Board Moderator)

< Previous Topic | Next Topic >

Pages: 1

Vents in cupboard containing boiler (Read 8082 times)

Maxheadroom

GDPR opt-out

Vents in cupboard containing boiler
Sep 13^th, 2006, 5:12pm

Hi all
Got a customer I do odd jobs for, she's just had her annual boiler service by BG and they've condemed the installation due to cupboard ventilation.

The boiler is in a cupboard with 4 air vents - 2 at top, 2 at bottom - 2 being at the front and 2 being on the side. The 2 on the front are 80mmx480mm the 2 on the side are 290mmx100mm all these sizes being the external dimensions and I don't know the free airflow for them. But I do know the side vents are adjustable and therefore not upto gas regs, top and bottom are slotted fixed vents.

She's been told she has to have 212 sq cm of airflow at the top and 424 sq cm airflow at the bottom.
Is this correct because she'll end up with more vents than cupboard!
Has the BG guy missed a decimal point somewhere as this works out as a hole aprox. 4" x 8" at the top and double that at the bottom. Plus of course the vents to give that much free airflow will be much bigger in area. I'm guessing about 3 of screwfix item number 39476 at the bottom and 1.5 of them at the top.
Also last question - can the vents go on the side of the cupboard to replace the existing or must they be cut into the doors as per BG.
Thanks for you help

IP Logged

Kent GDPR opt-out	Re: Vents in cupboard containing boiler Reply #1 - Sep 13^th, 2006, 6:07pm What is the make and model of the boiler,What is the output of the boiler, is the boiler an open flued boiler or room sealed.
Back to top	IP Logged

thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Vents in cupboard containing boiler Reply #2 - Sep 13^th, 2006, 6:17pm It will depend on the boiler make and model. Also the vents have to go to atmosphere either direct or via a room or space that is vented to atmosphere. Details on the boiler and the existing ventilation please.
Back to top	« Last Edit: Sep 13^th, 2006, 6:18pm by thescruff » IP Logged

CWatters

Super Member

Offline

"Daddy fick it" says James

Posts: 5150

Total Thanks: 58
For This Post: 0

Gender: male

Re: Vents in cupboard containing boiler
Reply #3 - Sep 13^th, 2006, 10:53pm

I couldn't see any data on the screwfix site but RS Components has a similar one that's 230w x 115h with more slots (RS Stock no. 348-7315 and similar).

The RS one has got a free area of 28 cm^2 so I suspect the screwfix one is more like 22cm^2 .. You would need 19 to make 424!

If their figures are right for this type of boiler you may need another type of vent.

IP Logged

thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Vents in cupboard containing boiler Reply #4 - Sep 13^th, 2006, 11:52pm It wont be far off CWatters
Back to top	IP Logged

Maxheadroom GDPR opt-out Total Thanks: 147 For This Post: 0	Re: Vents in cupboard containing boiler Reply #5 - Sep 21^st, 2006, 9:35pm Hi guys Got boiler details from customer (finally) - it's a Potterton Kingfisher 2 CF60 open flue. Thanks for your help so far. Maxheadroom
Back to top	IP Logged

CWatters

Super Member

Offline

"Daddy fick it" says James

Posts: 5150

Total Thanks: 58
For This Post: 0

Gender: male

Re: Vents in cupboard containing boiler
Reply #6 - Sep 22^nd, 2006, 9:34am

Best make sure this installation is perfect.. as you know if they don't get enough oxygen they make C0 rather than CO2

The Potterton site appears to have the installation manual (double check the model) and it mentions ventilation on page 7 and elsewhere..
http://www.potterton.co.uk/products/literature/Potterton_Kingfisher_MF_Install.p...

If I've read table 2 right for the CFL60 the vents need to be:

Upper 198
Lower 396

(sq cm free area)

Best double check the boiler model and confirm with Potterton... None of the models in the table need the exact areas you mentioned (212 sq cm of airflow at the top and 424 sq cm airflow at the bottom) so what were they refering to?

Is the Kingfisher "Mf CFL" the same as the "CFL" for example.

I'm not a gas fitter!

IP Logged

Maxheadroom

GDPR opt-out

Total Thanks: 58
For This Post: 0

Re: Vents in cupboard containing boiler
Reply #7 - Oct 3^rd, 2006, 12:20am

Hi all,

Thanks for your help - customer has had confirmation from BG and they swear they're correct!

One last question before I start making Swiss cheese styleee MFI units - are the vents OK to go in the front and side of the cupboard or MUST they all go on the front or side?

Cheers for you help - must say if CORGI guys have to know all this sort of thing then they DESERVE to all drive brand new Merc Sprinter vans while us mere mortals drive ex BT Transits Grin

Maxheadroom°

IP Logged

CWatters

Super Member

Offline

"Daddy fick it" says James

Posts: 5150

Total Thanks: 58
For This Post: 0

Gender: male

Re: Vents in cupboard containing boiler
Reply #8 - Oct 3^rd, 2006, 8:56am

I had another look at the Building Regs and in particular Part J here (pdf)...
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADJ_2002.pdf

Diagram 32 on page 39 also covers this. It says the top vent must be 1000 mm^2 per KW and the bottom must be 2000 mm^2 per KW. This is the input power not the output.

The Potterton Kingfisher 2 CF60 appears to have an input power of 22KW...
http://www.potterton.co.uk/products/literature/Potterton_Kingfisher_MF_Install.p...

So the areas work out at 22,000 mm^2 (= 220 cm^2) and 44,000 mm^2 (=440 cm^2) which is slightly bigger than they said!

I can't find anything that says the vents have to be on the front back or sides.

IP Logged

Maxheadroom GDPR opt-out Total Thanks: 58 For This Post: 0	Re: Vents in cupboard containing boiler Reply #9 - Oct 5^th, 2006, 12:14am Thanks CWatters and co for your help. Last question - jigsaw or chainsaw!!! Thanks guys
Back to top	IP Logged

thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Vents in cupboard containing boiler Reply #10 - Oct 5^th, 2006, 7:32am Matters not where you put the vents, Provided they are into the same room or space
Back to top	IP Logged

Pages: 1

(Moderator: thescruff) - (Moderator Group: Board Moderator)

< Previous Topic | Next Topic >

Ask The Trades › DIY Forum › Plumbing Questions › Vents in cupboard containing boiler