Hi I live In a 3 storey property the combi boiler is on the ground floor, the radiators on the middle floor get warm but nothing like as warm as the gound floor. The radiators on the top floor only get luke warm, I have tried bleeding them over and over again makes no difference. The way the system is connected is like a electrical series circuit, 2 15mm going up to the top floor and in a loop around the rads with a connecting pipe between each rad valve. The combi boiler was fitted just before we moved in, The remains of the old system can still be seen in the loft and i believe the old boiler was on the middle floor. Is it a case that the pipe work is not suitable for a combi boiler on the ground floor? Can anybody help please? Thanks in advance.