boiler keeps going on and off (combi alpha 240e)?

I had this problem on a Baxi Bahama 100 combi. Nearly drove me mad. After several days I changed the fan proving switch.
The rise in temperature in the fan compartment must have just pushed the switch into open circuit, shutting down the burner with no lock out. Boiler would then restart briefly. Naturally before cracking it I had bought an expensive PCB board to no avail.
Good luck.

Peter
September 2007