After several flow switches and a new PCB over the years my Baxi boiler has developed another fault. I am assuming to be the divertor valve ( or operating solenoid) the boiler runs okay to heat up the C.Heating but when attempting to get hot water continues to fire up (in C.H. & hot water mode) but domestic water remains cold. If switched to water only, boiler flashes up, pressure rises into red zone & boiler locks out with overpressure groans & rumbles. There is No pressure relief from safety outlet. Does this boiler have another regular fault.

Steve Peacock, December 2006

sounds like your divertor valve is ok, otherwise when you run the tap the boiler would continue to run ok but your rads would get hot. its more likely to be a blocked plate heat exchanger, the boiler produces the heat ok, bit it cant transfer it to the hot supply so consequently the residual heat left in the boiler begins to overheat the boiler, crashes and bangs and the pressure increases.

doug, December 2006

The Bahama's have been an "issue" within the industry since their launch, it would unfortunately seem like your diverter valve has bitten the dust and I would recommend replacement... Although depending on your financial situation, a replacement boiler could be worth the spend if you require a reliable heating and hot water appliance...

Over the past year I have removed about 30 of these units due to reliability issues, it would seem as though you either get a good one, or a bad one... Some I've worked on never seem to give any problems whatsoever, yet others seem to always have visits with the doctor.

GasAid.co.uk, December 2006