SORRY THE BOILER IS ARISTON EURO COMBI A/27MFFI FITTED 2ND TEMPERATURE PROBE AS EVEN NEWONES CAN BE FAULTY BUT STILL BOILER RUNS WHEN MAINS SWITCHED ON & NO PROGROMMER CONNECTED--HOT WATER HEATS WHEN TAP TURNED ON BUT NO TEMP CONTROL [VERRY HOT] PROBE ACTIVATES MICRO ON HOT WATER WHEN CALLING--DIAPHRAM WASHER OK IN FLOW SWITCH CAN ONLY PUT FAULT DOWN TO PCB LOW VOLTAGE BOARD AS THE TEMP CONTROLS ARE ALL ON HERE--WOULD THE DEVICE TO FIRE UP WHEN BOILER FALLS BELOW 3 DEGREES [AS IN INST MAN BE AT FAULT] EXPENSIVE BUT POSSIBLY LOGICAL REPAIR ---THANKS FOR YOUR POSSIBLE REMEDIES BUT BOSS WANTS CURE ASAP