My central heating radiators are hot upstairs and cold downstairs, except the kitchen rad which is next to the boiler. I've bled all the air out of the radiators - there wasn't much - and checked that the pump impeller is turning under power. The pump is a Grundfos 15-50, about 8 years old I think.

John Whiteoak, January 2009

Turn of the valves controlling the rads which are working one by one & keep checking if the heat begins to circulate. It sound possible that you have a build up of sludge & may need to have your system flushed.

Tez, January 2009

Are you sure the pump is running and not just buzzing as it sounds like the problem is the pump.Hold a large screwdriver to the head of the pump and put your ear to the end of the driver.You should be able to hear if it is running or just buzzing.

Tony S, January 2009