alpha CB24

Hello, and hopefully someone can help with this.

I am getting alternating red/yellow lights flashing on my alpha cb24 combi and as a result no hot water or central heating. The manual indicates this is a low pressure fault, but the water pressure is reading ok on the guage and I've drained and refilled the system

I've replaced the DHW flow swich (£49!!), dismantled the flow diverter valve itself and inspected it for damaged seal/diaphragm but it seems ok and the mechanism operates freely by hand. Depressing the DHW flow switch manually has no effect.

The pump turns freely by hand so I am now beginning to suspect the primary pressure switch

Does anyone have any other ideas that may help? I'd rather not fork out for another new (unncessary) switch if possible.

Thanks very much.
jon

As a follow up, I gave the diverter valve a bang with a spanner and it started up again! Stripped it down and cleaned it and lubricated the rubber parts. Put it back in boiler and it didn't work until I gave it another bang....so it's working for now but I guess it is just on the way out.

Boiler is only 4 years old, and reading other peoples experiences similar faults with Alpha boilers I am not impressed and wouldn't buy another.

No good telling us, get on to Alpha and give them some stick.

Untill you lot take issue with the rubbish, its in their interest to for them to break down.

Should be easy enough to check the primary flow switch electrically - voltage across the two orange wires.
If a boiler won't start it's going to be an electrical signal somewhere. Rubbers in the DV won't stop it!
Judicious whacking can be a diagnostic tool , but not as generally useful as a multimeter!

ChrisR said:

Should be easy enough to check the primary flow switch electrically - voltage across the two orange wires.
If a boiler won't start it's going to be an electrical signal somewhere. Rubbers in the DV won't stop it!
Judicious whacking can be a diagnostic tool , but not as generally useful as a multimeter!

Click to expand...

I will get a multimeter and check, though it did seem that a tap freed up something stuck in the diverter valve. Thanks.

Going to write to alpha as well and complain that this type of fault seems all too common with this particular boiler.

All the DV does electrically is push the flow switch , which as you said had no effect when operated manually. SO the fault isn't with the DV, unless there's more than one.
The PCB's do go intermittent on those.