worcester bosch 28si

[Leonard Williamson]

Hi, can anyone help,my boiler has been losing temp control,i.e going over 3 bars on pressure gauge,with the result that the central heating water is discharging out of the pressure relief valve outside the house,which results in me having to top up all the time,I have turned down temperature control dial on front of boiler for c.h.temp,and it is working o.k,between 1 bar and 2bar without loss of water, I have always had temp dial on full setting before and it worked fine,has anyone any idea what could have caused this to happen.would be grateful for any advice thanks.