vaillant turbomax pressure increase

[2005jasp]

I have a vaillant turbomax 242 combi bolier and last week had the prv replaced after the central heating pressure dropped to zero. The old prv was was not holding over 0.5 bar when I tried to fill the system. The problem now is that the pressure keeps creeping up past 3 bar whether the boiler is on or off. The filling loop is still attached but the valve is off. I've just turned off the main water at the stopcock and bleed the system to 2 bar to see if the pressure goes up over night and hopefully prove whether the filling loop is leaking. First question, is the filling loop easy to replace and secondly am I thinking along the right lines with the problems I'm having?

Thanks for your help!

 

[petit_pablo]

Filling loop or hot water heat exchanger.

 

[2005jasp]

Thanks for the response Pablo.

Overnight the pressure has decreased slightly...is the next step to replace the filling loop valve?

Thanks.