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

USER INSTRUCTIONS

The SELECT electronic time switch can automatically switch ON and OFF twice a day at whatever times you

During installation the installer selects either 24hour or 5day/2day or 7day programming options via 3 position

switch on back of unit (see installation instructions).

24 hour programmer option runs same programme every day.

5 day / 2 day programmer option allows different ON / OFF times at weekend.

7 day programmer option allows different ON / OFF times for each day of week.

The unit is designed to eliminate possibility of accidental changes to your programme. Buttons normally

visible only affect your set programme temporarily. All buttons which can permanently change your

programme are located behind the flip-down fascia panel.

For convenience, the programmer has a built in programme which for many people is perfectly satisfactory

but it can be changed quite easily (see section CHANGING PROGRAMME TIMES).

Built in programme is loaded by pressing RESET button (H) (use a non-metallic pointed tool for this) and is

Weekdays (Mon-Fri) 1-ON > 1-OFF 2-ON > 2-OFF

Weekends (Sat&Sun) 1-ON > 1-OFF 2-ON > 2-OFF

If unit is installed as a 24hour programmer the built in programme will be the same for each day (as Mon-Fri

SELECTING OPERATING MODE

MODE button (A) selects the operating mode. There are 4 modes as described:-

(continuous)

2 (on twice) Switch will be switched on or off exactly as stored programme, twice per day.

1 (on once) Switch will be switched on only once each day.

It will switch on at 1st ON time and off at 2nd OFF time.

SETTING TIME AND DAY

The display indicator will move to position above clock symbol and will be flashing.

Press +/- buttons (D&E) to adjust time. Time will change quicker if pressed continually.

Press DAY button (F) to move indicator to current day of week.

Press SET button (B) three times if you wish to return to normal run state. Indicator on

If you wish to change programme on/off times (see next section).

The unit has a built in timer which will cause the programmer to return to normal run state automatically if a

period of 5 minutes passes without any buttons being pressed.