Maybe I'm doing something wrong. But... with a 275W heater or 2x 175W vanilla heaters, I can heat a large 340 tiles room to 21 °C no problem.
But I need ~750W / 750 heat units on the DBH electic boiler + radiators to reach the same temperature.
So looking at this, it's way less efficient than a vanilla heater?
I'm aware the boilers will only run in intervals, as the radiators buffer heat, but that's math I can't do without looking into the files.

What's the most efficient boiler?
is gas better than electric?
Tips for getting more efficient with the central heating?