Renew old heating with heat pump or gas boiler and domestic hot water heat pump

Hello, my gas heating system (roof heating center) is 22 years old, the solar thermal system is also 22 years old. The solar thermal system no longer works properly. The first HVAC technician recommends demolishing the heating system and solar thermal system and installing a Weishaupt heat pump. He has been installing only Weishaupt for several years. A second HVAC technician recommends renewing the gas boiler and additionally installing a domestic hot water heat pump. Photovoltaic system commissioned with 9 modules Luxor ECO LINE HALF-CELLS M120/380W, to be expanded by at least 3 modules when the solar thermal system is dismantled. Mid-terrace house, fully equipped with radiators, 106 m² living area, 4 people, approx. 10,000 kWh gas consumption. ZIP code 76661, annual average temperature 11.1 °C, standard outside temperature -10 °C. Heat pump to be installed on the roof according to the HVAC technician. Regarding the hybrid system, can I install the heat pump for domestic hot water in the basement even though there is no hot water pipe? How extensive would the effort be if additional pipes have to be laid? Installation in the attic is not possible.

There can't be that many defects in the ST system. It is a relatively simple system in which a heat transfer fluid is pumped through a few pipes. Reading in and operation is done by the plant operator themselves. Demolition and something new is often uneconomical. Question: can photovoltaic panels be installed additionally?

Is the gas heating still working? If yes, do nothing yet. Use the upcoming winter to get the flow temperature as low as possible. This can be achieved through individual structural measures. Only then can it be decided whether a heat pump can be operated economically at all.

Hello, thank you for the reply. The gas heating only works for hot water, it has been taking a very long time for days. The manufacturer is Ferroli. Not really well known. I don't want the heating to fail in winter. After all, it is already 22 years old. Photovoltaics have already been commissioned as mentioned above. I want to replace the ST with additional photovoltaic modules.

Does the gas heating currently not produce hot water? For example, in winter when [ST] does not work. I have a 17-year-old [ST] myself; if it is scaled up, leaking, and the technician has to come several times and needs scaffolding or a lift, the repair is not worth it. Therefore, a new gas heating system and no heat pump, IMHO.

Hot water via the central heating or via the [St] takes a long time? A rushed switch to a heat pump can become very expensive

Does the gas heating currently not produce hot water? For example, in winter when the ST does not work. I have a 17-year-old ST myself; if it is calcified, leaking, and the heating technician has to come several times and needs scaffolding or a lift, the repair is not worth it. Therefore, new gas heating and no heat pump, IMHO

ST is already 22 years old, both heating specialists recommend dismantling the ST and instead adding modules for photovoltaics. What speaks against a heat pump and photovoltaics? And gas heating plus BWWP would be the suggestion of the second heating technician. BWWP in the basement where the dryer and washing machine are located. The problem is only the cold water line in the basement.