Central heating will not refill

[irceb]

Hi all
I 've had to replace a radiator down stairs, this meant draining the system. When i tried to refill the header tank filled up but the water goes nowhere. The system is a traditional back boiler with header tank, pump (in the airing cupboard) and hot water tank.

Any help would be great, thanks.

 

[marios_kin]

Problem is most likely to be either an air lock or a blockage at the first elbow after a vertical dropfrom the header tank.

 

[irceb]

I dont think its a blockage. If its an airlock how do I get rid of it?
There is very little air coming out of the blead valves on the radiators.

 

[oilman]

Why do you think it's not a blockage? This is far more likely than an air lock. The usually occur near to where the feed pipe joins the rest of the pipework, and need something mechanical to clear them.