Appliance Repair Questions? Ask a Technician for Answers ASAP
Hi . I would recommend that when it switches off next, with a multimeter/ voltage tester a check should be made to see if there is still power to the boiler ROM the external controls.this would confirm whether it is a boiler fault or an programmer , room stat fault.
Sorry , but anyone looking at the system would want to confirm that first. Sorry to dissapoint you with good practice