hi i have a remeha 28c which is just 5 years old, i keep getting E7 flashing up, no hot water but if you dont run the hot water the central heating works, but if you run the hot tap it comes warm for a start and then goes cold, i then have to reset the boiler? the water pressure is just over 1 1/2 bar so that seems ok . . . does anyone have any ideas ?thanks pgm948...............