As it has been working ok since it was installed a few years ago, I thought the problem might be caused by something simple. Many thanks for your advice.
Many thanks for your reply, bengasman. Do you mean CH water temperature control? Regardless of the setting, the boiler still repeats on/off cycle. If you mean something else, I would be grateful if you could clarify.
Hello
Potterton Performa 24: DHW is fine. When CH is switched on, it works normally until all the radiators are hot, then it goes on and off repeatedly every 10 - 20 seconds. Any help would be very much appreciated. Many thanks.