Radiators cool down but boiler stays on?

[wave]

Hi,
We have just had a new Ideal Logic boiler fitted, and I am a bit confused about somenthing. We set it to come on for a certain amount of time, it fired up at the time set, radiators heated up fine, then a little while later when the temperature was reached, the radiators cooled down, and the boiler said then 'pump overrun' and stayed on... And again this evening, it came on, radiators heated up and then when it got to the set temperature they cooled down but the boiler stayed on right until the end of the time period set.
As I understand it, a boiler only comes on in a set time period if the temperature falls below the set temp, and doesn't stay on when the radiators have cooled down?? It just seems wasteful, not to mention noisy! Or have I missed something?!
Thanks

 

[HERTS P&D]

Call back the installer, get him to check it and show you how it works!

Andy

 

[wave]

Yes I am going to, I just wanted to try and arm myself with info so I don't sound completly clueless to them lol
Is it usual for a boiler to stay running (it says 'pump overrun') after radiators have cooled down? As with my mums boiler it clearly clicks off as soon as the required temp is reached.
Thanks