Alpha CB24X - Red Neon Question

[meep]

We have an Alpha CB24X which has been installed for about 4/5 years. Today the Red Neon light came on when turning on the hot water tap... the water failed to heat and the boiler fan etc eventually turned off.

The boiler has been in hot water / central heating mode since I can remember.

I reset the boiler and then turned on the central heating, this worked fine, I turned it off and tried the hot water, Red Neon again.

Reset the boiler again and moved it to the hot water only mode, turn on a hot tap and it works fine, it will continue to work on demand continously in this mode.

If you put it back in mixed mode and try the hot water, it will fail again. The above cures it and hot water is again available.

Does anyone have any ideas of what may be at fault to cause this problem? Unfortunately the troubleshooting guide only covers hot water in that mode, not hot water in mixed mode.

Thanks in advance...

 

[superdupergasman]

Think you have just been lucky, what does the red neon mean when only in HW mode??

 

[meep]

There are 2 options in the troubleshooting flow chart for "Neon A Illuminated Continuously" in HW mode only... they both ultimately end in "Replace PCB" as the other options (i.e. ignition / gas flow) as probably OK.

Some ideas on other tests to complete or recommendations on how/best ways to fix would be great.