Also you should have a 0 degree drop in temperature across the radiator flow pipe and return measured by temperature of you main pipes, only then you can balance system properly doing this to each radiator rather than just by feeling pipes, an old school plumber always carry’s balancing temp tools!
Firstly your radiators are cold on bottom due to build up of sludge in them you need to flush system firstly before re filling and balancing
To balance the heating system, and get most of the radiators equally as hot, you need to turn all the radiators off and then open the furthest radiator away fully open both sides, then you need to make sure the hottest pipe to the radiator is turned up high and regulate the flow from the opposite valve. Then from here each radiator closer to the boiler, the flow must be high and the the return shut right down. If your radiators are quite cold ( especially at the bottom ) it is most likely iron debris and sludge in the system, and would need powerflushig.
Nick shares his story of finding local tradespeople in his new area.
