Free Air requirements

[andymchorsham]

Is there an easy way to calculate the free air requirements, and thus the vent size, in a room when fitting a back boiler with conventional flue

 

[kevplumb]

depends on the heat input of the appliance

 

[PEDANTICVINDICTIVEMAN]

Nett input of gas fire, add onto nett input of back boiler, take away 7, x remainder by 5 leaves Cm2 of free air vent required, make sure air vent fullfills regs eg cant be hit and miss type or have fly screen.
If boiler and fire are badged in gross you have to convert to nett before starting calculation by dividing by 1.1 (I think).

 

[kevplumb]

i was just going to work it out for them

 

[PEDANTICVINDICTIVEMAN]

Let the boggers do some of the work Kev

 

[brumylad]

I'm NOT Corgi reg. but, if it turns out you need a really big vent, maybe you could use two or more smaller ones.

 

[ChrisR]

It will come out to a dirty big hole. Popular option is to use a nice brass vent in the floor (if suspended and not concrete cos that's harder). Then the occupant can put a phone book over it despite being told not to.

 

[whatif]

it'll not be a kick in the arse off 100cm2, if you are lucky enough to be able to fit it in the floor (are you on the ground, does it connect to outside air via enough airbricks, does it NOT connect to another property) you could use 7671 from www.bes.ltd.uk @ £7.85 + del + vat

 

[kevplumb]

if its not free air and you have to buy it can you have a smaller vent

 

[ollski]

All valid enough but the ventilation requirements will be in the instructions.

 

[kevplumb]

All valid enough but the ventilation requirements will be in the instructions.

yeh but wots instructions

 

[PEDANTICVINDICTIVEMAN]

Instructions are them thick wedge of papers with everything in them, BUT WHAT YOU REALLY WANT TO KNOW when fitting an appliance,

Fit nosecone to part A frame 25 (b), connect onto part F, measure distance from moon to Uranus, add on 25mm or 1500mm if vertical horizontal kit (extra can be ordered from spares dept 3 year delivery) slot into top of boiler, ignore bag of totally unessesary washers and gaskits as these are for 20,000Kw model but if flue length over 2mm dont fit allready factory fitted restrictor if fitted if not ignore and go to page 25, WHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

 

[kevplumb]

morning mate
have a nice day