potterton ultra 2 switching to lockout after draining and refilling system?

after draining the system to fit new rad valves the system was refilled and turned back on it fired up ok then it switched to lockout. the heating engineer made some enquiries with a collegue and was told that it is the pump that has gone i found that strange as it was working on the morning of fitting do you have any idea if this is right or will it be something else? i would appreciate any help thank you
greg dodd, June 2005


done
you have air in the boiler , and its gone to lock out to protect the boiler. run the boiler with the boiler stat switched off, this should clear the air.

Dave Champkins, September 2009
Sounds more like an airlock to me , Was the programmer switched off while the heating was drained? on both the water and the heating sides if not and the pump was running dry then yes the pump will have burnt out

Steve, June 2005
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