I'm planning a retrofit 10mm microbore system for a small house. I know that the standard method is to run individual circuits to each radiator from a manifold on a 22mm pipe, although I have put two radiators on one sub-circuit before without any problems. However, in this case, it's going to be difficult to use the standard system on the Ground Floor. If I take the 22mm pipe as close as I can, am I likely to have any problems if I then connect four radiators on one 10mm microbore sub-circuit ? Maximum distance from the 22mm pipe is going to be about 10 metres.