i wonder if any of you expert plumbers out there can help me with this one . my radiator in my kitchen wont heat up .the hot water heats up the pipe but wont enter the radiator un less i bleed it , i have tried the thermostat pin and its ok (moves in and out) i have taken it off the wall and out side and flushed it with hot water which filled it up so it was warm ,so no blockage . i have put hose on the out feed pipe to see if this was blocked but the pressure gauge went up on the combi . this has me baffled can anyone help please thanks john .