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.
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.
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