GRANT oil combi boiler PRV leaking

[Exedon]

Assuming expansion vessel is correct pressure and you have disconnect filling loop to make sure that's not passing , if pressure continues to rise when boiler not working plate to plate.
We have changed one or two.

 

[Nihad]

Assuming expansion vessel is correct pressure and you have disconnect filling loop to make sure that's not passing , if pressure continues to rise when boiler not working plate to plate.
We have changed one or two.

expansion vessel is pre set to 1 bar.

I haven't tested the filling loop

and yes, the pressure continues to to rise when boiler isn't working.
sorry I don't understand the "plate to plate" bit, what do you mean by this??

 

[Exedon]

Plate to plate is the stainless steel lump top right of your pic.
That's what heats hot water
If pressure still rises when you disconnect filling loop and boiler off that’s the problem.
Bit of a bitch to change normally disconnect heating flow and return above boiler.

 

[Nihad]

Have replaced plate to plate
Also non return valve
This sorted the pressure problem

However the ch is constantly run even when the thermostat is off
I haven’t touched the wiring at all and it worked fine before

 

[Exedon]

You mean the heating indicator light on and heating constantly on even when heating should be off?
Not caught the rocker select switches?