Thanks tony, going with the flow problem theory. I tried mains pressure through the header tank feed to try to clear a possible air lock. As a result the boiler seems to stay on longer before the boiler stat cuts in. Turning the boiler stat down slightly makes the boiler cut out earlier...
installer will not be avaliable for 2 weeks (holiday) im not sure if it is designed to modulate. If the fault requires a heating technician i will have to wait. Thought it might be something I could handle. Thanks
I have a 2 week old Ideal Classic HE boiler on an old open vented indirect system. From cold the Boiler will run for approx 10 mins then shut off. then cutting in and out at approx 1 min intervals until the CH and/or HW temp is met by the thermostats. No undue noise or airlocks aparant in rads...