Angela wrote:
I have a potterton combi boiler. On noticing that the pressure had
fallen slightly below the indicator level I asked a neighbour what to
do (we all have the same system). He showed me how to top it up but
at the same time managed to over pressurise it and it went into the
red zone. He released the pressure again using what he said was a
pressure release valve. Since then the pressure keeps falling and I
am having to top it up every day.

Now I am wishing I never asked for advice. Is there something that I
can do or is it a job for the professionals? It's due for a service
next week but I would rather not have to pay out for a repair when it
maybe something very simple.

Thanks

Angela

Most likely some muck from the system is lodged in the pressure relief valve
so is stopping it shutting off completely.
Try operating it for a 1/2 a second or so to flush it.
The pressure relief valve should be shown on the instructions which the
installer ought to have left you.
If not it can be traced by following the small pipe that goes through the
outside wall,back into the boiler.
The relief valve normally has a small (red?) lever which you lift to
operate.
You will have to re-pressurize the system to 1 bar when the CH is cold
afterwards.