Please Help 100cm2 Air Vent for Back Boiler???

[SGHUK]

Hi All,

I've recently had my back boiler serviced by British Gas and they have advised that new regulations state we must now have 100cm2 air vent through our wall as apposed to the one that we currently have that goes thought our floor, I have been advised that the ideal one would be a 100cm2 Core Vent which can be found on this site model BM418 http://www.stadium-ventilation.co.uk/vents/downloads/Blue_leaflet_New.pdf however the site states it comes with an anti draft baffle which when fitted reduces the free area to 70cm2 , if I have this with the baffle fitted will this not meet the regulations specified or will this be acceptable,

Please advise,

Kind Regards,

Aiden

 

[SGHUK]

Is there someone here that works for British Gas that could possibly advise me?

 

[gas_man_gaz]

what back boiler do you have?

 

[Mr Smyth]

Current vent requirements are not new. Your boiler has always required suitable ventilation dependent upon the kW input of the appliance.

As far as I am aware.......

New vents through the floor have to be ducted throughout their length. Very difficult to do retrospectively. Existing vents are not req to be ducted. Just classified Not To Current Standards.

Often vents through the floor are undersized. Although the floor vent maybe the correct size the vent or vents that it communicates with are often inadequate. They too have to measure the same or larger than the floor vent.

Air-bricks have very small holes. Although the outer hole may measure +15mm the inner hole is often only 9mm. Therefore you require 112 holes to achieve the 100cm2. Stadium do a plastic air-brick that provides 125cm2 from a vent 216 x 152mm (6x9)

Hope this helps

 

[Peruse]

If the regs say 100cm2 then that is what you need, if you fit the vent without the baffle you are OK however I always fit the black hole so you comply with the regulations and still have anti draft if I remember correctly BM720.

 

[SGHUK]

Thanks all,

Peruse that would be ideal but id'e prefer a core vent as its easier to fit by just drilling a hole with a core drill rather then removing bricks, if you or anybody know where I could get one that meets the 100cm2 requirement please let me know, otherwise would it be ok to use the baffle and just remove it for services? after all the 100cm2 is just an advisable amount isn't it?

Kind Regards,

Aiden

 

[boabcelt]

New under floor ventilation doesnt need to be ducted throughout its length if you can prove that space under the floor does not communicate with neighbouring property i.e. openings in the dwarf wall. Terracotta air bricks can be smashed out and replaced with plastic ventilator bricks of the required size easily enough. You may not need exactly 100cm sq, but it would suffice for all back boiler and fire models I can think of.

 

[Peruse]

Same question as gas_man what back boiler do you have?

 

[powell30]

Example.

Fire 6kw
Boiler 20kw
total 26kw
minus 7kw for adventious air = 19kw

Direct to outside would be 19x5cm squared = 95cm squared total required.

If the calc says 100cm then 100cm it needs to be (squared) NOT advisory.

 

[Agile]

Most BBUs I come across are considerably less than 20 kW.

Interesting question for newbees! If the boiler is range rated, say from 14 kW down to 9 kW then does the vent have to be for the set power of 9 kW or the full power of 14 kW? ( Plus the fire front of course ).

 

[boabcelt]

The vent needs to be calculated based on the appliance maximum heat intput e.g 16.8 kW for a 57/4e plus whatever the output for the fire front, be that 5 or 6kW.

 

[Boilerman2]

Erh? Heat INPUT of the Fire please!

 

[namsag]

Boabcelt the figure you have gave is output not input.

Agile you need to get out more the most popular backboilers fitted where the baxi 551 and 552 with inputs of between 21 and 22kw.

OP
100cm2 is like an industry standard for back boilers but the Manufacrurers instructions will tell you minimum size required for that appliance.