I am gas safe registered and have a problem with a Linea 24 which has left me stumped, even Vokera technical can’t seem to help on this one.
The Linea 24, provides heating well but only provides luke warm water – The display stops at 38 degrees. When DHW is selected it fires and the gas valve modulates down to 5 mbar straight away. I have read the other posts and have stripped the boiler down but have not managed to rectify the fault.
Here’s the history:
Main heat exchanger was replaced in December as this had a small crack and was leaking. 2 weeks later the DHW fault occurred.
• DHW thermister and main thermister checked, but then replaced to avoid doubt on the advice of Vokera – still no change
• Plate Heat Exchanger tested – Upon closure of cold inlet isolation valve only read 65 on the display, however this was replaced to avoid doubt – Still no change.
• Diverter head checked, Heating Flow/ Return Pipes do not get hot, so not flowing round heating system, motor retracts properly.
• Diverter spindle checked, cleaned lubricated and replaced – Still no change.
• Non return valve checked, cleaned - Still no change.
• Bypass checked, cleaned, cleaned - Still no change.
• Mesh filter cleaned - Still no change.
• DHW flow restrictor checked, cleaned and replaced – Still no change.
• Spindle on PCB checked to ensure that the dial is functioning correctly and this is fine.
I have tested the hot water with a by holding a thermister externally on the DHW thermister connection and the boiler then maintains full flame (10mbar), so the PCB/potentiometer are fine, but when plugged back in the thermister in situ, it modulates down and stays at low flame.
I have stripped the boiler down and cleaned all areas that I think could be causing a restriction, but am truly stumped now. The boiler did have some dirt in it, but I have seen worse and most of this has been cleaned up now. I must be missing something. I would appreciate any advise on this tricky fault.
Thanks,
Kal
The Linea 24, provides heating well but only provides luke warm water – The display stops at 38 degrees. When DHW is selected it fires and the gas valve modulates down to 5 mbar straight away. I have read the other posts and have stripped the boiler down but have not managed to rectify the fault.
Here’s the history:
Main heat exchanger was replaced in December as this had a small crack and was leaking. 2 weeks later the DHW fault occurred.
• DHW thermister and main thermister checked, but then replaced to avoid doubt on the advice of Vokera – still no change
• Plate Heat Exchanger tested – Upon closure of cold inlet isolation valve only read 65 on the display, however this was replaced to avoid doubt – Still no change.
• Diverter head checked, Heating Flow/ Return Pipes do not get hot, so not flowing round heating system, motor retracts properly.
• Diverter spindle checked, cleaned lubricated and replaced – Still no change.
• Non return valve checked, cleaned - Still no change.
• Bypass checked, cleaned, cleaned - Still no change.
• Mesh filter cleaned - Still no change.
• DHW flow restrictor checked, cleaned and replaced – Still no change.
• Spindle on PCB checked to ensure that the dial is functioning correctly and this is fine.
I have tested the hot water with a by holding a thermister externally on the DHW thermister connection and the boiler then maintains full flame (10mbar), so the PCB/potentiometer are fine, but when plugged back in the thermister in situ, it modulates down and stays at low flame.
I have stripped the boiler down and cleaned all areas that I think could be causing a restriction, but am truly stumped now. The boiler did have some dirt in it, but I have seen worse and most of this has been cleaned up now. I must be missing something. I would appreciate any advise on this tricky fault.
Thanks,
Kal