Hi Bob-I am having same problem- very intermittently -but found that boiler kept on running after hot water tap turned off-but when turning on and off hot water again quickly burner shut down- so I am suspecting DHW FLOW SWITCH at this stage-dont know how to test it yet-but think it must be sticking on occasionaly.This fault only seems to happen after hot water used and when boiler starts up it runs for about 6 minutes then shuts off-weird!
Stuart
April 2011
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