My daughter has an Alpha CB24 Combi boiler fitted and it`s got a problem

..It intermittently will not fire-up either on Hot Water or Central heating, or
when it does work it will suddenly shut down.

I had a look at it and the Domestic Hot Water (DHW) flow valve microswitch was
suspect.
I`ve changed it and all was well.....for nearly an hour ...then back to square
one...nothing fires-up again for at least 5 minutes.. ( I suspect that this
might be due to preprogrammed delays built into this system??)

I`ve got more info but the first question to ask is does anyone know anything
about Alpha boilers and the sequence of events that makes this boiler fireup.

ie. Which sequence the switches and sensors (temperature etc.) . come
"into-play".

This boiler is not 3 years old and it`s already had a new pressure switch
before I fitted this flow switch.


Failing getting an answer re this Alpha brand , can anyone recommend a decent
AND reliable combi boiler.(....if there IS such a beast !!! )

{)

TIA