ᐅ Controlled ventilation and heating system: retain settings during power outage

Hello everyone,

I have a question that just came up:
What happens if the mechanical ventilation system or the heating system lose power for an extended period?
Do they lose their settings?
Because all of this was specifically configured for the house.

The reason:
Everything was set up for us, but then we disconnected the power and turned it back on occasionally, since we don’t need the devices during the interior construction work.

I’m not sure how long the power can be off without losing the settings.
I want to avoid having to call the technician again.

Both devices are from Vaillant.

Thanks!