My Ravenheat combi boiler fires up Ok for Hot water , shower or sink taps , gives proper hot water for approx 3 mins then shuts down for approx 45 seconds , then fires up again to repeat the cycle over and over ????? diverter works fine and air flow checked and replaced with no improvement .... could it be an overheat issue ?? , but been Ok for last ten years ..

rodney, February 2012