When you open a hot water tap the boiler fires up and the burner comes on. This heats the water and this water does not flow past the diverter valve to the plate heat exchanger.
The boiler overheats due to not removing the heat away from the boiler . no heat travels to the ch when the tap is open
hello over the last week i have had BG out and the keep mucking up my boiler
i have a hot water problem- the boiler fires up but the flow of water dose not go past the diverter valve. BG diagnoased this for a thermistor and replaced the part no better. naw they are scraching there heads lol...