Warmflow burner problem

[steve1]

The burner on our warmflow boiler seems to have a mind of it's own at the moment, when I adj the room stat for the heating to fire up, the burner, if it feels like it, will fire up for a short while, ( maybe 1/2 an hour ), then shut off, again maybe for about the same time, if not longer, ( no real pattern ), although you can hear the fan running on the burner.
The hot water can be the same, you will get hot water until the store runs out then cold, and as with the heating the burner is not firing up all the time.
Have had a quick look, and it would appear that there is no supply getting to the coil on the solenoid valve for the oil supply to the burner, definately not a coil fault as I've put a tester on the connections to it.
I notice that there is a control box screwed to the side of the burner where the wires for the coil come from, I take it that this contains relays etc. should I look in there or is it just a throw away unit, or, am I barking up the wrong tree.

[netherfield]

Could easily be the control box at fault,usual way is to swap it out,although they usually go to lock out when there is a fault.

[steve1]

changed control box, still have the same problem. Could it be the photo-cell that detects the flame at fault.

[netherfield]

Should not be,if the photo cell can't see a flame it should put the control box in to lockout ,which shuts everything down,except the fan until that cools down anything still hot.

Or at least that's how the Danfoss box works.