In general, heating systems in existing buildings are replaced with new systems every 15 years. The investment costs for boilers and gas heaters, as well as the installation costs, are manageable, and the supposed modernization of the heating system can be easily assessed and implemented by installation companies.
However, these systems will not help you achieve renewable heat supply or reduce CO2 taxes. To achieve these goals, the conversion to bi- or multivalent heating systems is required, where multiple heat generators work together.
This involves, for example, combining environmentally friendly heating devices like a heat pump with a conventional heat generator like gas to heat buildings. What has become commonplace in new construction has not been addressed in existing buildings until now!