Relative has helped a friend replace a bathroom radiator with a ladder type chrome towel rail. Straightforward job. Baxi ch system in three bed semi. Bled the new towel rail until water appeared. Switched on system, towel rail gets hot only at bottom two thirds. Bled again and no water appears but it is lying there, a third of the way down. Then used a funnel to fill with water but it just kept taking it. After twenty jugfulls checked header tank in loft which was found to be full of warm water and overflowing. New rail is a few cms taller than the old radiator.
First ever example of pushing water uphill?
DaveK.