depends whether the fault indicator light is flashing, if it is the boiler could be in a lockout condition where the burner has failed to ignite, if after five attempts the burner doesnt light the electric will be cut to the gas valve and the light will flash once a second approx, to re-set turn CH control anti-clock all the way then back to the required temp setting, the boiler should now try to re-ignite after 4 minutes. check gas supply for interruption.
chris p, January 2017
