new heat pump as a replacement for oil heating with existing radiators

At least that explains the heating demand of 58000kWh. I still consider the annual performance factor of 4.9 to be optimistically calculated. Such values are achievable with brine, or in the Rhineland or coastal areas, where it rarely gets really cold. But not in Thuringia.

He promised me a constant 23 degrees, and he even wants to guarantee that in the contract. Otherwise, I could claim it as a defect.

The car salesman can also promise you that you can always drive at 200 on the highway. That you then burn 20 liters of premium fuel is not his problem. Good that your heat pump offer includes the electric auxiliary heater. That makes the heat cost three times as much in winter compared to the plan, but so what, he didn’t promise low costs. And if you then have higher heating costs than with oil, that is not a defect either. It depends on the usage you want. Enough joking around. You should get a more serious offer. One that will probably be more expensive in investment but not also in operation. Or does it help if you exchange expensive oil for expensive electricity but also have the costs for purchasing the heat pump? Cheaper is a sensible plan with new radiators (according to needs) and significantly lower annual heating costs without loss of comfort. Calculated over the long term.

... and above all: Reputable devices are subsidized at 55%. I don't know if the DWW part is on the list of eligible systems.
Then the DWW offer is only cheap because you do not receive any subsidy. Or rather, the operator cannot pocket it.

... and above all: Serious devices are subsidized at 55%. Whether the DWW unit is on the list of eligible systems, I don’t know. Then the DWW offer is only cheap because you don’t get any subsidy. Or rather, the operator can’t pocket it.

The subsidy would actually be formulated airtight in the contract. I can withdraw at any time if the KfW does not subsidize 50% of a maximum of 30,000. It even states that DWW will reimburse the money if it should turn out afterward that the KfW later partially reclaims the subsidy when demanding values again (do they really do that sometimes, or is that just a rip-off?). I am still seriously considering the R32. They strongly advised me against propane because there have allegedly already been explosions with customers and I was informed about it, so that I would have to bear the consequences myself. I am really very grateful to all participants for the lively discussion here in the forum and it makes me rethink everything. Two offers are still in the pipeline. If it becomes more expensive, I will try to get possibly 45,000 EUR subsidized (two-family house).

The indoor air units are not possible at all with R290. Air conditioners still rely on R32 because the explosive R290 is only allowed to be installed outside, and no refrigerant lines are permitted to run inside. R32 cannot explode, but it is just as deadly if inhaled in enclosed spaces. As long as the refrigerant lines are intact, both gases are harmless. Yes, there were once explosions with R290 because a heat exchanger froze, then refrigerant entered the heating circuit and was vented into the heating cellar through a quick vent. That is why such vents are only permitted on the outdoor unit.

Indoor air units are not possible at all with R290. Air conditioners still rely on R32 because the explosive R290 may only be installed outside, and refrigerant lines leading indoors are not permitted. Although R32 cannot explode, it is just as deadly if inhaled in enclosed spaces. As long as the refrigerant lines are intact, both gases are harmless. Yes, there were explosions with R290 because a heat exchanger froze, allowing refrigerant to enter the heating circuit and be vented into the heating cellar through a quick vent. That is why such vents are only permitted on the outdoor unit.

THANK YOU! And do you advise me to bring DWW on board if I can’t get further with other companies (and only then)? Or is R32 an absolute no-go?