Anybody care to help with this problem? This is the submission I sent to Worcester Bosch this morning, hoping for some guidance or advice, even a diagnosis, but especially an answer to my question about the diagnosis offered in my WB Servicing Instructions manual. All I got was an invitation to book a visit from one of their engineers. This was my submission:
‘DHW mode seems to work normally, outside of CH periods, in the sense that when you turn on a hot tap you get hot water. During CH periods, however, the DHW mode becomes faulty as soon as the CH mode becomes faulty. This is what happens: (1) In CH mode and when the burner is firing, the CH demand indicator light is on, as is the flame detection indicator light, and the fan is working. In these conditions I can get DHW from the taps as well as CH. Five or six minutes into the heating session, however, the burner stops firing, the flame detection indicator light goes out, the DHW demand indicator light flashes fast, and the fan stops. The CH demand light stays on, and so does the pump, but with pump over run this may be normal. Whilst the DHW light continues to flash in this way no attempt to get hot water from the taps succeeds. To get DHW from the taps I need to turn the boiler off and then on again to clear the flashing light problem and start the CH process again, or move to a non-CH period on the programmer. (2) A few minutes later, and without any user input, there is the sound of a switch coming on inside the boiler and the fan comes on, then the burner, and the flashing DHW demand indicator light goes out and is replaced by the flame detection indicator light. (3) This return to normality lasts for a few minutes, then the same sequence of burner going out, flame detection indicator light going out, the DHW demand indicator light flashing fast and the fan stopping until the next return to normality, is repeated in an endless cycle. According to the Installation and Servicing Instruction manual for the 28CDi this flashing DHW demand indicator light corresponds to Fail Point J (p27), which suggests an 'Air Pressure Fault' has occurred (p33). And yet, everyone I have spoken to about this problem seems to think it is caused by the notoriously unreliable water diverting valve fitted in this boiler. I am inclined to trust Worcester Bosch trained engineers rather than just any old local plumber (accredited or not) to decide which diagnosis is the right one, if either is. There is no obstruction in the boiler’s flue and neither has the flow of air to the boiler changed in any way since it was installed. The system pressure is normal (1 bar).’
Anyone any ideas?
karenminnitt
‘DHW mode seems to work normally, outside of CH periods, in the sense that when you turn on a hot tap you get hot water. During CH periods, however, the DHW mode becomes faulty as soon as the CH mode becomes faulty. This is what happens: (1) In CH mode and when the burner is firing, the CH demand indicator light is on, as is the flame detection indicator light, and the fan is working. In these conditions I can get DHW from the taps as well as CH. Five or six minutes into the heating session, however, the burner stops firing, the flame detection indicator light goes out, the DHW demand indicator light flashes fast, and the fan stops. The CH demand light stays on, and so does the pump, but with pump over run this may be normal. Whilst the DHW light continues to flash in this way no attempt to get hot water from the taps succeeds. To get DHW from the taps I need to turn the boiler off and then on again to clear the flashing light problem and start the CH process again, or move to a non-CH period on the programmer. (2) A few minutes later, and without any user input, there is the sound of a switch coming on inside the boiler and the fan comes on, then the burner, and the flashing DHW demand indicator light goes out and is replaced by the flame detection indicator light. (3) This return to normality lasts for a few minutes, then the same sequence of burner going out, flame detection indicator light going out, the DHW demand indicator light flashing fast and the fan stopping until the next return to normality, is repeated in an endless cycle. According to the Installation and Servicing Instruction manual for the 28CDi this flashing DHW demand indicator light corresponds to Fail Point J (p27), which suggests an 'Air Pressure Fault' has occurred (p33). And yet, everyone I have spoken to about this problem seems to think it is caused by the notoriously unreliable water diverting valve fitted in this boiler. I am inclined to trust Worcester Bosch trained engineers rather than just any old local plumber (accredited or not) to decide which diagnosis is the right one, if either is. There is no obstruction in the boiler’s flue and neither has the flow of air to the boiler changed in any way since it was installed. The system pressure is normal (1 bar).’
Anyone any ideas?
karenminnitt
