Viessmann Vitodens 100-w configuration with Nest

[profarvin]

Hi all,
I had a new Viessmann Vitodens 100-w boiler (the new version) installed last year. The guy who was installing and commissioning it had never seen or commissioned this boiler before, so I guess he didn't do it in the most efficient way:
1. I've got Google Nest thermostat but it looks to be connected as a regular switch on/off thermostat - not in Opentherm mode.
2. The boiler display and Vicare app always show that Heating circuit 1 is off. But the boiler does switch on when Nest wants so. If I switch on Heating circuit in the boiler, it starts working based on the Vicare app schedule.
2. Flow temperature gets to 70 when triggered by Nest. Adjustment of regular/comfort/reduced flow temp in the Heating circuit doesn't change anything (well, probably because the boiler thinks the Heating circuit is Off all the time).
So my guess is that the installer connected the Nest as an external heating demand trigger. I went to parameters menu and changed "Flow temperature for External demand" from 70 to 55 - it helped, and now Flow sets around 55 when triggered by Nest.

I want the boiler to be as efficient as possible. The question I have now is - can I do something with the configuration myself to make it more efficient (I don't know if weather compensation is enabled at all, for ex), or shall I invite an engineer who can reconfigure it to work with Nest via Opentherm (dynamic flow temp change, etc)?

Any advice?

 

[Knappers]

I think there are terminals for opentherm on boiler but I would consider leaving it as is and fit viessmann outdoor temp sensor to control boiler temps

 

[Stevebn]

I've had a viessmann 100-w with Nest for 3 years. The Nest is connected via the opentherm connections so it can modulate the boiler. I spoke to viessmann and they said you can't have both Nest installed on opentherm and the outside temperature sensor installed, (so I didn't install the temp sensor).

 

[profarvin]

I've had a viessmann 100-w with Nest for 3 years. The Nest is connected via the opentherm connections so it can modulate the boiler. I spoke to viessmann and they said you can't have both Nest installed on opentherm and the outside temperature sensor installed, (so I didn't install the temp sensor).

Thanks, this is really helpful. Has it been useful or more efficient to have the connection via opentherm?