Morning,
what you are doing right now is deliberately calculating the heat pump poorly.
At which point?
What is right, you will only know in 10-20 years. I am currently considering something similar, we built with a gas heating system 8 years ago and I am thinking about prematurely getting rid of the gas heating system.
It should already make sense with the current parameters. Otherwise, you can also react later.
Installing a heat pump now will almost certainly protect you from having to switch to district heating at some point. Once the mayors together with the municipal utilities realize that with a mandatory connection you can achieve almost unlimited prices and profits and can award great contracts to their allies for implementation, there will be a very big gold rush. Just the connection to district heating in a few years will be in the same order of magnitude as the price of a heat pump today. Digging up the garden and laying pipes is expensive. And after that, you are at the mercy of the pricing policies of the district heating operators. According to the current legal position, a mandatory connection for a heat pump cannot be enforced.
And according to the legal position in xyz years, it will be different again.
If you wait until your gas heating system breaks down, you will have quite a problem getting a heat pump at a good price on short notice. That ends with you installing another gas heating system again, which you then have to replace with a heat pump after 3 years. That makes even less sense.
You would have the same problem if your heat pump breaks down. I also don’t see people installing a gas heating system on short notice only to switch back to a heat pump in 3-4 years. And by common understanding, a heat pump has a significantly shorter lifespan than gas heating systems, which can easily be 30-40 years old in existing stock.
A heat pump also doesn’t cost the 20-30k€ as Dahlbomii writes. I have a finished offer here for 24 k€, of which 40% subsidy is deducted, leaving 14.4 k€. If I then also take into account that because of the possible cooling function of the heat pump, I can save the actually planned retrofit of an air conditioning system (only a minimal version in the living room), I come to about 10k€ costs. (Yes, that is nice accounting...).
And in the worst case, the heating lasts 15 years until 2039, your gas heating system would have lasted until 2045, and due to falling demand it remains at 1:4 or even lower until then. And in 2039 according to your argument above, you then have to install a gas heating system again on short notice and then a new heat pump in 2042.