On Wed, 17 Feb 2016 14:40:16 +0000, Pumpkin <
primrose...@gmx.com>
wrote:
>I have exhausted my web search trying to find out if combi boiler
>emissions are just vapour or carbon monoxide emissions.
>
>Does anyone have an answer to my query.
I assume you mean condensing boiler - the one with a steamy flue? They
are essentially slightly acidic water vapour. They will contain
elevated amounts of Carbon Dioxide compared with fresh air and tiny
amounts of Carbon Monoxide (typically 0 .002%). More than a foot or
so away there is no risk of CO poisoning and the flue gas CO content
will be well below the HSE limit of 50ppm.
For the dwelling in which they are fitted Boiler flues are not allowed
to be fitted within 300mm (12") of a window which can be opened. This
is a safety limit.
The danger from gas burning appliances occurs if there is insufficient
incoming air - this can't really occur these days with room sealed
boilers which take air from outside and vent waste outside. All the
cases you read of are old room ventilated boilers. Restricted air
means incomplete combustion (yellow rather than blue flame) and
increased CO. All gas appliances do produce some CO (Including gas
hobs) but only tiny insignificant amounts if combustion is complete.
As far as neighbouring properties are concerned much more restrictive
rules apply to reduce nuisance from the acidic steam in the plume. The
rules are in - “Guide to the Condensing Boiler Installation Assessment
Procedure for Dwellings”, (Section 6).
http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_CONDBOILER.pdf
These say that a condensing boiler flue should be “a minimum of 2.5
metres from a facing wall, fence, building or property boundary”, and
British Standard BS5440-1, states that condensing boiler flues should
not be sited where the plume is “likely to cause a nuisance”.
You can get flue diverter kits which can be used to take the flue up
and out of the way.