During heating my 50FF boiler is making popping noises almost as if the water is boiling inside. It is not happening all of the time, but does so randomly? maybe moreso when it fires up in the morning. It happens regardless of whether it is DHW or CH. It is connected to a Gledhill thermal store and everything still works fine. I have turned the stat down on the boiler but it makes no difference, could it be the stat? I'm sure it has an overheat cut-out though.
yes it does have an overheat cut out, it could be a dirty system, bit difficult to diagnose without hearing it though.
I would get the heat exchange checked, also when was it last serviced
