Help with Boiler!

[laurajy2k]

I have a potterton combi promax he plus. For the past week the pressure has been in the red zone at number 3. Have tried bleeding the radiator which lowers the pressure but then a couple of hours later the pressure goes back up again.
Even when the pressure is on 3 then the heating and hot water is still working. Have re-pressurised the system as shown on the user guide but to no avail.
What could be the problem?

 

[Boilerman2]

Yuo need to DE-pressurise the system sounds like your expansion vessel needs some air put into it call a Service engineer

 

[bengasman]

Possibly the filler is letting by, or the hex is leaking, or the ev is knackered, or you simply have not filled the system correctly.

 

[pontered]

it could be as simple as the filling loop is letting water by, check this buy disconnecting it(silver braided hose, with a tap at each side) if it is passing it will constantly fill the system slowly....

if you disconnect it and it still continues to fill the plate heat exchanger is leaking into the heating circuit

if when the system cools down the pressure dropps the expansion vessel is flat, needs pumping up with air, or the hose connecting the vessel to the boiler is blocked