Can I have a flue from my combi boiler coming out under my kitcen window?

no if its within 300mm its illegal. Also the boiler has got to be 200mm from a floor or base of any kind for access to values etc. This is to the manufacturers instructions. If fitted incorrectly it will invalidate your cover

spx steve
May 2009

Ask the "contrary to regulations" chap to show you the regulation...

Nice picture (Scottish) here with a table of what's permitted - I would guess rest of UK the same...

http://www.scotland.gov.uk/library2/br/brf-09.asp

The way I read it is that the Flue must be 300mm below the OPENING window and 150mm from anything that may catch fire like a wooden or plastic window sill.

Your local council will be able to advise you - best to get it right particularly if you might one day wish to sell the property.

Good luck...

Peccavi
May 2009