Hi, can anyone shed any light into this. My plumber recently changed a couple of radiators for me. At the same time he added bulldog valves to every radiator in the house as we wanted to be able to control the heat in each room. Anyway, now many of our radiators are hot at the top and lukewarm at the bottom. i dont think it is sludge in the rads as they all worked fine before. Could it be the new valves? Shouldn't the radiator be the same heat all over?. They are all set to 5(highest setting). Some radiators are fine and are hot all over. I dont understand. Can anyone help cos i dont think my plumber knows - He is blaming the old pipes but everything worked fine before we changed 2 rads and put the valves in. Any ideas anyone - much appreciated.