How much should a new gas boiler cost?

Good day, we own a 20-year-old house with a wall-mounted boiler. Sieger HG11. Since our exhaust gases are discharged through an external wall connection and not through the roof, our boiler was limited to a maximum of 24kw in hot water operation. Now our boiler is approaching the end of its life, and before I get many offers, I wanted to kindly ask here what something like this would cost. A new wall-mounted unit is to be installed, if possible again through the external wall. The district chimney master has given his approval. Our house has a heating area or living space of 110m3. Annual gas consumption ~11000kw.

You should urgently skim through how climate change works. And with such low consumption, definitely switch directly to a heat pump!

No, heat pumps do not work here because this is a former mining area.

Air-to-water heat pumps should also work in mining areas. Only a box goes in front of the house. No, seriously: we need to be climate neutral in 15 years. Gas can't make that work. Do the next generation (and probably your wallet) a favor and switch now.

Someone has to install the new boiler. This person usually also sets the prices, and the range can be very wide, depending on the work involved. This can usually only be clarified with an on-site appointment.

Wait and see, soon gas will be green energy:p
When it comes to the boiler, it depends on the power, equipment, etc. Installation costs are added on top. Just get a local provider.
A new gas boiler is certainly much more economical because it is a condensing boiler. The installation effort is significantly less than converting to a heat pump.
With the money saved, you can heat for many years. Electricity is not getting any cheaper either. Currently, it doesn't look like Germany will return to nuclear power. We'd rather buy from the neighbors then…