Difference in purchase cost between gas pump or heat pump

Yes, I will also install these.

The heating element is turned on from the bivalence point. It depends on the load according to the mode of operation. More in the range of -5° to -9°.

The heat pump should generally not be used below -20°. But that is rather unlikely for us.

Yes, the minimum temperatures really depend heavily on the latitude in Germany. In the south, you will probably need to choose an air-to-water heat pump with a lower bivalence point.

**Edit: Are there actually air-to-water heat pumps that switch on a small gas boiler when the bivalence point is reached? Instead of an electric heating spiral.**

so you will also install the newer "WH-MDC05H3E5"?
Because I am currently looking at the data of this heat pump. "Operating range up to -20°C". What actually happens if it gets colder? Does it mean that from -20°C the heating element switches on first and then you heat 1:1 with electricity or how?

You have that more or less with every air-water heat pump. The thing also freezes. There are also heating elements for automatic defrosting, etc.

**Edit: are there actually LW heat pumps that switch on a small gas boiler when the bivalence point is reached? Instead of an electric heating coil.

That would render the whole system absurd. Because then you would need a LAS and gas connection again anyway. The costs would outweigh the benefits.

That would lead the whole construct to the absurd. Because then you would need a LAS and gas connection again, etc. The costs would outweigh the benefits.

But if the gas connection is already on the property and you actually only pay for the gas that is consumed. For a duration of about 1-2% of the total operating time per year, during which the output is below the bivalence point. But sure, even heating with electricity (= heating element is on because below the bivalence point) is relatively expensive for the short time. It will still clearly be more economical than acquiring / maintaining a small extra gas boiler + LAS costs, etc. That's true.

Yes, I will install these as well.

The heating element is switched on from the bivalence point. This depends on the load depending on the operating mode. Rather in the range of -5° to -9°.

The heat pump should in total not be used below -20°. But for us, this is rather unlikely.

I just quickly searched on DuckDuckGo and found articles that partly show significant minus temperatures in Bavaria in recent winters (the most extreme was Funtensee, 28.02.2018, -40.3 degrees). If I build in an area where it can sometimes get to -20 degrees and the heat pump switches off at -20 degrees. Then ideally I fuel the hopefully installed fireplace, right? Otherwise, you'd be sitting in a house that wasn't heated overnight?

But I do understand that -20 degrees are becoming increasingly rare / are rarer.

There is a "Wärmepumpen Klimakarte" where you can read the relevant temperatures.

Where is the problem if the heating element turns on once a year? That's what it's there for.

When smartly controlled, you ideally only heat the house at midday anyway when the sun shines on your photovoltaic system.