Halstead Combi Boiler Central Heating keeps filling up

[WaterWorks1]

Hi

I have a Halstead Finest Gold Combi Boiler haven't had the central heating on for about 7 months and the hot water has been fine.

Now when the central heating comes on the pressure gauge rises and the blow off activates at approx 3bar.

Does this mean it is filling through the diverter valve and if so can it be changes easily and whats cost should it be?

Any assitance much appreciated

Cheers

 

[kevplumb]

expansion vessel needs recharging / replacing see FAQ

prob the prv as well

 

[WaterWorks1]

this is what I thought initially but the system continuously fills, if it where the expansion vessel surely the gauage would rise when the c/h was on and then it would need topping up again.

As it stands it doesn't drain the system down and the system just fills its self when on when the filling loop is conpletley disconnected. Turn the water supply off to the house and it works ok.