ᐅ Replacing an Old Heating System with a Heat Pump or Gas Boiler Combined with a Domestic Hot Water Heat Pump

Hello, my gas heating system (roof heating central unit) is 22 years old, as is the solar thermal system. The solar thermal system is no longer functioning properly. The first builder recommends demolishing both the heating system and the solar thermal system and installing a Weishaupt heat pump. He has been installing only Weishaupt products for several years. A second builder recommends renewing the gas boiler and additionally installing a domestic hot water heat pump. A photovoltaic system has been commissioned with 9 Luxor ECO LINE HALF-CELLS M120/380W modules, which will be expanded by at least 3 modules when the solar thermal system is removed. The property is a mid-terrace house, fully equipped with radiators, with 106 m² (1,141 sq ft) of living space, housing 4 people, and approximately 10,000 kWh annual gas consumption. Postal code 76661, average annual temperature 11.1°C (52°F), standard outdoor temperature -10°C (14°F). According to the builder, the heat pump is to be installed on the roof. Regarding the hybrid system: can I install the heat pump for domestic hot water in the basement even though there is no existing hot water pipe? How extensive would the work be if additional piping needs to be installed? Installation in the attic is not possible.

There really shouldn’t be that many defects with the thermal solar (ST) system. It’s a relatively simple system where a heat transfer fluid is pumped through some pipes. You need to study it yourself since you are the system operator. Demolition and installing a completely new system is often not cost-effective. Question: can photovoltaic panels be installed additionally?

Is the gas heating system still working? If yes, don’t do anything for now. Use the upcoming winter to lower the supply temperature as much as possible. This can be achieved through certain structural measures. Only after that can it be decided whether operating a heat pump is even economically viable.

Hello, thanks for the response. The gas heating system only works for hot water, which has been taking a very long time for days. The manufacturer is Ferroli, not very well known. I don’t want the heating system to fail in winter. After all, it is already 22 years old. As mentioned above, the photovoltaic system has already been commissioned. I want to replace the ST with additional photovoltaic modules.

Does the gas heating system currently not provide hot water? For example, in winter when the solar thermal system isn’t working. I have a 17-year-old solar thermal system myself; if it becomes calcified, leaks, and the heating engineer has to come several times and requires scaffolding or a mobile elevated work platform, repairing it isn’t worthwhile. Therefore, a new gas heating system and no heat pump, in my humble opinion.

Hot water from the central heating system or the water heater takes a long time? A rushed switch to a heat pump can be very expensive.

Grundaus schrieb:

Is the gas heating system currently not providing hot water? For example, in winter when the solar thermal system (ST) isn’t working. I have a 17-year-old ST myself; if it becomes scale-blocked, leaks, and the heating contractor has to come several times and requires scaffolding or a lift, repair isn’t worth it. That’s why I prefer a new gas heating system over a heat pump, in my opinion.

The ST is already 22 years old, and both heating professionals recommend dismantling the ST and adding extra photovoltaic modules instead. What are the arguments against a heat pump combined with photovoltaics? The second heating contractor suggests gas heating plus a domestic hot water heat pump (BWWP). The BWWP would be installed in the basement where the dryer and washing machine are located. The only issue is the cold water pipe in the basement.