Air vent size

by **jontee** » Sun Feb 08, 2009 11:37 am

What is the minimum size for an air vent to comply with gas central heating regs. Checked in Projects, but couldn't find an answer :?
Thanks

by **htg engineer** » Sun Feb 08, 2009 4:40 pm

There isn't a minimum or maximum size, it all depends on the appliance(s) in the room.

There's different calcs for different situations - if you explain the problem we may be able to offer advice.

htg

by **rosebery** » Sun Feb 08, 2009 4:59 pm

They changed the requirements again last year and the bureaucrats are going to keep pushing the requirements for older systems up until they are ID so replacement is the only option.

Jontee - methinks you may have been told that your current installation is NCS or even AR? If it was BG and you have received an expensive quotation for replacement of your boiler (as if by magic) get a second opinion.

by **jontee** » Fri Apr 03, 2009 8:35 pm

NCS - Not to Current Standard? Yes this was it. Basically, BG said that if it wasn't done by this year, my Baxi would fail the safety test.
Any idea what sort of DIY job it is? Cheers

by **htg engineer** » Sat Apr 04, 2009 11:24 am

"They changed the requirements again last year and the bureaucrats are going to keep pushing the requirements for older systems up until they are ID so replacement is the only option.

Not true - the correct air supply (ventilation) is essential for any gas appliance to work correctly and safely. Undersized vents are classified as AR - upgrade or install vents - problem sorted - it's not rocket science.

Jontee - methinks you may have been told that your current installation is NCS or even AR? If it was BG and you have received an expensive quotation for replacement of your boiler (as if by magic) get a second opinion."

I understood they wanted you to upgrade the ventialtion - that's all they're saying - no new boiler - is that right ???

Jontee - what make and model of boiler do you have ? what ventilation do you have at the moment ?

Open flued appliance, Max heat input (kw) - 7 adventitious ventilation x 5 = vent size in cm2
example
27kw -7 = 20
20 x 5 = 100 cm2

htg

by **rosebery** » Mon Apr 06, 2009 9:51 pm

"Not true"

Which bit? The one about requirements change? - which I believe they did or;

the one about they are going to keep pushing the requirement up? OK I'n speculating but I'll put a fiver on it.

Cheers