boiler losing pressure?

my vaillant combi boiler is loosing pressure when heating off, with no signs of any leaks

ryan blake
March 2011

Yes, pressure constantly dropping boiler in use or not,
no leak from pressure relief pipe outside.

M Jeeves
December 2008

do you lose pressure in an hour if boiler is not in use ie no heating being used?

Is it leaking from pressure relief pipe outside?

there are a few pressure problems but have different symptoms,
pressure rising with boiler off, (eg pin holed exchanger)
pressure rising and discharging from pressure relief when using ch resulting in zero pressure when cooled, (eg expansion vessel fault)
constant pressure loss whether boiler in use or not (faulty pr valve not shut or leak)

iain
November 2008