my boiler lights and runs, heating all the rads, but it keeps going and over heats the rads and the presure on the gauge gos into the red

dell, November 2010

is the red led light on pcb on with taps off. if yes hot water flow microswitch is stuck on, boiler thinks water running and will stay on untill its overheats, locks out and steam excapes thru air release at top and safety valve at bottom, pressure guage will pulse very high with steam

deano, November 2010