Radiators warm at the top cold at the bottom

[janemorrison3]

hi, just switched heating on to find that after usual annual checks, bleeding raiators etc the radiators are warm at the top and cold at the bottom except for the bathroom one which is first in-line and warm throughout. The pump sounds as if it is running and the speed can be varied by the dial on the top, but it is very hot (Myson SMC SD53), I'm not sure of it's age, please advise if you can from this description, do I have 'pump-lock' or should I just replace the pump which is easily isolated by cut-off valves eaither side so hopefully wouldn't have to empty the system.

Any advice would be gratefully received, many thanks Jane MM

 

[twgas]

if the pump is hotter than the pipes going into/coming out of it the chances are you need a new one. firstly, though, I would suggest turning the system off - both heating and hot water - and letting it cool completely.
Then unscrew the black nut on the end of the pump, when loose, gently pull and spin the rotor - should move quite easily, then turn heating back on if pump still doesnt work try tuning black nut whilst heating is on.