Buy / Sell Heat Pump Privately

we have lowered the desired temperature until it was right in the house. Right now AT -1, desired temperature 19, in the house 22.5

Friday noon to Monday night) 93 kwh. And then from Tuesday until today, around 6 pm: another 40 kwh

The consumption is relatively easy to calculate and to compare with the values from the heat pump. If I neglect the solar and internal gains as well as the ventilation losses, then the following calculation (with my values): Enclosure surfaces 360 m² x transmission heat losses 0.2 = 72 x delta T outside to inside e.g. 20 degrees ≈ 1500 W x 24 hours thus 36 kWh thermal loss. That should be about 8 to 10 kWh electricity per day.

Can you install it yourself or does it have to be done by the HSLer?

You can actually do it yourself and it should not pose a problem for the warranty.
For me, the Vaillant technician who was on site and confronted with my question did it, but said that it's "actually just two wires" that need to be connected to the bus.
If I’m not completely mistaken, the module is also WLAN capable.

This week I have had extremely low electricity consumption for heating (the sun must be having an effect), but the hot water preparation probably still needs a bit of optimization....!?

So, after the pump consumed another 20 kWh since yesterday, I had a bit of time this morning to take a look at the professional craftsmen level. Yes, room control was already off and the heating curve was 0.4!!! I have now also changed it to 0.2 for the time being. The heat pump seems to keep leaking, at least everything is wet underneath it in the rear area. Unfortunately, I don't catch the moment when it happens, otherwise I would know where it comes out. Can you provoke a defrosting process?

Check in the test menu at the hydro station/tradesman level if it is available there. The code should be 17.

Is the hot water preparation working? In my hydro station, the valve was set to manual in the delivery state and was only changed to auto after I pointed it out. 20kWh of electricity per day is already massive. But are you also looking at the actual electricity consumption or the heat produced?

Ignoring the interior temperature and driving purely according to the heating curve is optimal for efficient operation

I would like to disagree with that. Interior-controlled heating is more efficient; at least the interior temperature should be taken into account when determining the required supply temperature. This significantly increases efficiency, especially during transitional periods, because in new buildings the heating can simply remain off when it is cold outside but still warm inside, and possibly solar gains occur again during the day. According to this principle, by the way, my heating has been turned off punctually since 01.03., and—wonder of wonders—even without heating cycles, the house is comfortably warm despite -2 degrees at night and 10 degrees during the day with corresponding solar gains.