In article ,
R D S wrote:
The ceiling and wall/ceiling corner above our boiler is slightly grey
having got that way over some years from previously 'is the ceiling a
bit grey there' to now 'it definitely is, yes'.

There's no CO2, there are 2 detectors in there.

I suppose the sensible answer is get someone in? Or is this normal to
some degree?

There is always at least some waste heat from a boiler. Which will draw
air (and dirt) to above it. Same as you get above a rad, given enough time.

--
*We have enough youth, how about a fountain of Smart?

Dave Plowman London SW
To e-mail, change noise into sound.