Sunvic Select 207 XLS 2PU Error

[Dave 2PU]

I installed a new Sunvic Select 207 XLS heating programmer and after several weeks it resets itself to the factory state flashing 2PU. When I reset it all seems fine but it goes for maybe 2-3 days or even a week and does the same again.

I returned the unit and obtained a replacement from the supplier (who in turn sent it back to Sunvic) but the same happened again, it appears to be totally random.

Incidentally Sunvic returned the original unit to the supplier saying they had bench tested it and it was in perfect working order.

I called the Sunvic help desk and they said to check the unit was sitting on the back plate correctly and suggested that the power supply was being interrupted and that the internal battery may be running down, which makes sense.

So I checked all connections and even replaced the wiring to the consumer unit but no change.

Is it possible there is an incompatibility between this unit and the boiler or motorised valves.

It is running a pumped system on a pressurised tank with HW and CH valves fed from a 7 year old Glowworm Hideaway boiler.

I am at a loss to know what the problem is, it's so random!

Hope someone can help