Combi boiler pressure Keeps rising ?

[lorry75]

Hi
i have a worcester Bosch 240 combi and after its been turned on running a couple of hrs the pressure is constantly rising to over 3mb. I have drained off the radiator to get the pressure back down to 1mb, but again the same thing still happens. Is this is due to the expansion vessel, if so - how do i top up the pressure myself. A couple of years ago, i had a problem where i had no heating or hot water and the engineer did say there was a problem with the expansion vessel, he then topped it up, i am sure he did this with a foot pump. Could it be that simple to fix the problem, just refill the expansion vessel???? If so do i just remove the expansion vessel connection and stick the pump on there, as i cannot see any other valves to connect to ??

 

[JPC]

it sounds like the ev.
is it an external one ?
or behind the boiler

if its external u can drain down and refill with a bike pump or similar..to about 1.5...(need a presssure gauge).(similar pressure to with u then fill the system)

but u might find the ev is knacked and u need a new one ?