should a 15/60 grundfoss pump be able to run 9 rads spread over 3 floors if it is positioned at the highest point (i.e loft) assuming everthing else is working fine. Has it got enough flow and power to get hot water in the heating down a good 5-6 metres and back up again. If not is there a more powerfull pump.(or add a second in line) It is in the worcester 35 cdi combi. Or is it borderline depending on insulation, pipe size etc. Any help appreciated.