I SEEM TO BE HAVING A PROBLEM WITH MY CENTRAL HEATING. ALTHOUGH THE THERMOSTAT ON MY BOILER IS LOW AT 2 AND THE THERMO TO REGULATE THE RADIATORS IS AT 18, AGAIN VERY LOW FOR THIS TIME OF YEAR - THE RADIATORS ARE TOO HOT TO TOUCH WITH THE HAND. I CAN ALSO HEAR WATER IN THE RADIATORS AND A CONSTANT BU...