I HAVE A HALSTEAD EDEN X TYPE CBX 32 COMBINATION BOILER, ITS ABOUT TWO AND A HALF YEARS OLD. THE PROBLEM THAT I'M HAVING IS THAT THE PRESSURE KEEPS DROPPING ON A DAILY BASIS AND I HAVE TO OPEN THE FILLING LOOP TO TAKE IT BACK UP TO APPROX 1.5 BAR. WHAT IS THE FAULT? CAN SOMEONE HELP?