Hello ! 
This doesn't mean that your boiler is working all the time ! 
These symptoms could happen when it just finished heating the hot water ! Perhaps there is no " flowcheck device"  on the radiators circuit , preventing a " thermo-syphon " move of some warm water !
Turn off the valves of the radiators or replace them by " thermostatic ( automatic ) ones !   sept 17-2007 JPh
Tha,ks for the feedback  when fixed !
                
 JPh
                
 September 2007