Floor vent for back boiler

stewart231 · 16 Sep 2006

Hi,

I had a recent visit by a Scottish Gas engineer to get my central heating system serviced. He said that he would not be able to do this until I fitted a floor vent due to some new regulation.

Is this true and if so what is the best type of vent to fit as most of the ones in my local DIY store are for walls or the flush fitting type. The suspended floor has external brick vents.

Also where should I put this vent (between outside wall and boiler etc)

Any help or advice appreciated.

TIA

doitall · 16 Sep 2006

Assuming BG have taken your money under a service contract, you are entitled to your money back if they refuse to honour it.

what boiler is it

ollski · 16 Sep 2006

If it is at risk it should not be worked on and left at risk bg or independant. Floor vent of 100cm2 should be fine provided that the sum total of all the brickwork vents add up to at least the same.

corgiman · 17 Sep 2006

I thought they were perfectly acceptable as longs as the are ducted from vent in flor to the wall??

ollski · 17 Sep 2006

corgiman said:
I thought they were perfectly acceptable as longs as the are ducted from vent in flor to the wall??

Perfectly acceptable but don't require ducting, presume op has no ventilation at all atm.

Agile · 17 Sep 2006

ollski said:
Floor vent of 100cm2 should be fine provided that the sum total of all the brickwork vents add up to at least the same.

Are you saying that even if there is a nice 100cm2 vent in the wall to the outside then a SECOND vent in the floor is required?

I dont think so! I think this is a badly worded explanation that 100cm2 is needed to go directly to the outside OR through the floor in which case the underfloor area MUST have the same 100cm2 to the outside!

I vaguely seem to remember that most BBUs work out at 46cm2 but whatever is needed if there are two vents in series I would want to oversize BOTH to take account of the increased air flow resistance.

Tony Glazier

ollski · 17 Sep 2006

Referring to the op who is asking about a floor vent with vents in the brickwork under the suspended floor. Most bermudas I see require about 97cm2 but I rounded it up. Must be sufficient ventilation from outside into the space under the floor. No requirement to increase series vents unless two or more between external vent and boiler. Hope that is clearer.

doitall · 17 Sep 2006

The ventilation is calculated at 5 cm² for every KW of the appliances maximum rated input in excess of 7KW.

BS 5440-2

ollski · 17 Sep 2006

Of course yes if no sizes are given in the installation instructions....they are though, usually in the mi's for the fire.

Paul Barker · 17 Sep 2006

doitall said:
The ventilation is calculated at 5 cm² for every KW of the appliances maximum rated input in excess of 7KW.

BS 5440-2

Less 35.

Oops sorry, you said that.

fitz1 · 17 Sep 2006

ahh but is that net input or gross. aint this job a pain in the brain and arse.

corgiman · 17 Sep 2006

fitz1 said:
ahh but is that net input or gross. aint this job a pain in the brain and a**e.

see below matey

stewart231 · 17 Sep 2006

Thanks for all the replies so far but I'm still a bit confused!

I have two wall vents (230x150mm) which are under the floor level. The floor has about 1ft of space between bottom of joist and the ground. I think that there is a sleeper wall between the vents and the boiler but the space above the sleeper wall and betwen the joists is open.

The boiler is quite an old Baxi Bermuda with front fire surround. So do I still need a floor vent and is so can this just be fixed to the floor or will it have to be ducted.

Also should I just place the vent to the side of the boiler/chimney breast so that it vents the room?

Thanks again.

doitall · 17 Sep 2006

A floor vent must be ducted to atmosphere.

The vent in the floor must be fitted in such a way as to prevent carpets etc covering the grill. E.G. a raised frame.

You would be better installing the vent through the wall to atmosphere above floor level, if possible.

You can place it anywhere in the room that the appliance is fitted, provided it cannot get blocked, either accidentally or deliberately.

Paul Barker · 17 Sep 2006

I thought it didn't have to be ducted as long as you are satisfied that there is suitable route to outside.

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Floor vent for back boiler

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