Is the power consumption and procedure for screed drying normal?

For me, nothing was dripping wet. Leave the window tilted open. The heat and moisture have to get out.

15kW? My heat pump only has 3 kW.

Tilted is rubbish. It has already been said.

Whether wet or not also depends on the screed.

Regarding the 20kW of the dryer, which actually only draws 8kW. Your 3kW heat pump probably has a comparable output in this weather.

Why does he do it with a heater and not with the intended heating? Is it not installed yet? Why?

Because the indoor units are often placed on screed (composite screed). Or the hot water storage tank. Most of this is done only after the screed is poured. It is a planning and coordination issue.

With monoblock, it could be done differently too. Not every heating system is as dumb as mine Vaillant. Or the base for the interior is poured beforehand. In any case, that would significantly reduce consumption if heating is done with a ratio of 1:4-1:5 instead of 1:1 (0.9?). But well, the installers usually don’t pay.

It would also work differently with monoblocks.

Monoblocks are really for DIY. A proper heating engineer prefers to use a real heat pump.
That way, the heating engineer can also earn better.

Addendum: Meanwhile, monoblocks are already available in two parts with an indoor unit like Panasonic.

Moisture is completely normal. Air out by opening windows fully as often as possible. I always vacuumed the windows and ceiling with one of those Kärcher window vacuums. But you have extreme moisture for a few weeks, that's just how it is. I then bought a construction dryer, which helped a lot. It extracted up to 50 liters per day.

I also heated with a heating device during the first week. Then I tiled one square meter in the technical room and placed the indoor unit of the heat pump/hot water storage on it and switched to heat pump operation. It's more efficient, but you won't save more than a few hundred euros this way. And for that, you take the risk of tiling on a screed that is not yet ready for covering. I did it, but a general contractor definitely wouldn't do that.

Your 3kW heat pump now certainly has a comparable performance in this weather.

I thought it was about electricity consumption. My heat pump has a max. electricity consumption of 3kW. Last night it even kicked in at 2 degrees. My old gas heating was always off from May to September.

I thought it was about electricity consumption. My heat pump has a max. electricity consumption of 3kW. Last night it even switched on at 2 degrees. My old gas heater was always off from May to September.

Yes, that's what it's about. Your heat pump uses less electricity for the same heating performance. So it's comparable 1:1 with the small difference in costs.