The difference in flow and return temperatures at each radiator varies between 2C (lowest) and 7C (greatest). Although all of my radiators get hot I understand the desired differential is 10-12C. Do they need balancing to achieve this differential? Would the effect of a greater differential mean a more consistent temperature? What would be the effect I would feel of such a low differential? Also the lockshield valve appears to be on the "higher temp" pipe on some radiators but on the "lower temp" pipe on others - is this normal or have the flow & return to some of these somehow got reversed?