Quite a complicated piece of kit.

Have hot water but boiler not responding to call for hot water to fill the central heating system.

The computer brain is not indicating any errors.

Is anyone familiar with this system or do I need to contact a specialist Atag engineer again?

Thanks for any help.

I have an atag premiere. If you run the hot water it cuts off the supply for heating (you probably know that though) Have you tried rebooting it (takes about 20 minutes for it to work it all out again)?