ideal classic boiler fault

[redimp7]

My Ideal Classic with a sealed system pod about 7 years old.
If i fill system to one bar when cold it fires up to nearly 3 bar when running
It is constantly getting air in and needs filling weekly the prv body only has been replaced to no effect

Why does it build up so much pressure or is guage faulty?
Many thanks

[matt1e]

i doubt that the gauge is faulty. inside the boiler is a pressure relief valve that usually vents off at about 3 bar so you are probably losing water via the vent so have a look outside to see if there is any water dripping from the vent pipe. as to the causes it could be a problem with the expansion vessel,problem with the pump,or the filling valve could be passing (I know no-one ever does but you are supposed to take the filling loop off after filling)
gasman on here will probably give you a better answer

[gucciman]

why do you say it is constantly getting air in the system?

my money would be on the expansion vessel, may need repressurising.

[matt1e]

or gucciman wil give a better answer lol

[redimp7]

Thanks for your help
Yes the PRV is blowing off as seen by a driblet of water on tube probably this is also sucking air back in
What I cant understand is why it goes as high as 3 bar when on cold it has zero pressure

I have tried repressuring expansion vessell but wil probably have to replace it