Need your assessment for the renovation of a rental property

I want to add to the half-knowledge that a [Pallet-Heizung] may require more space than an oil heating system, otherwise it has to be refueled more often. No idea to what extent this is true.

The heating burner is quite small, can be 50 x 50 cm. The pellet storage with 5-6 tons requires space, but there are already good fabric silos, and with an oil tank the amount is almost the same soon. Maintenance is somewhat more, but there is funding from the BAFA, I believe 40% of the costs. It also depends on the radiators; pellet heating works well for classic radiators due to the high flow temperature – if you have underfloor heating, then I would consider a heat pump.

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But it also depends on the radiators, pellets work well for classic radiators due to the high flow temperature - if you have underfloor heating then I would consider a heat pump.

We have underfloor heating, even in the basement. A heat pump was also recommended to us. Precisely because there are apparently new refrigerants - or soon will be - that are supposed to be more efficient than the current refrigerants. However, without solar power, I am still wary of the electricity costs due to the longer frost periods we have here.

It depends on how well the house is insulated - we currently pay 55 euros per month for heating and domestic hot water - the house is from 2011 and has 165 m² + basement. Brine heat pump with deep drilling then certainly costs 25,000 euros. Gas is of course initially cheap to install - it depends on the financial and life situation - gas can initially help cheaply in the short term over the next 10-15 years...

Precisely because there are apparently new refrigerants

The new ones are worse than the old ones (as of 2021). Even my new heat pump model has a slightly worse efficiency on paper than the 20-series model.

However, without solar, I still shy away from the electricity costs due to the longer-lasting frost periods we have here.

I would also be worried about the high gas, oil, and pellet costs during the frost periods ;-).
Solar in winter doesn't help either due to the lack of sun.

The new ones are worse than the old ones (as of 2021). ...

If that is true, then you can hardly rely on (almost) anything anymore :confused:

... The high gas costs, oil costs, pellet costs in the short-term periods would also scare me ;-). ...

:D Obviously, I have (again?) expressed myself imprecisely. To my knowledge, the efficiency = the effectiveness, for example, of a gas heater is independent of the outside temperature. Thus, the higher consumption = higher heating costs would only be due to lower outside temperatures (simplified: one variable). In the case of an air-to-water heat pump (Luft-Wasser-Wärmepumpe), the efficiency = the effectiveness depends on the outside temperature. Thus, the higher consumption = higher heating costs – compared to above – would be due to lower outside temperature and lower efficiency (simplified: two variables). That is why brine heat pumps are supposed to be more efficient than air-to-water heat pumps. If I am wrong, I would be glad :) Of course, I am aware that gas and air-to-water heat pumps use different ‘media’ for heat generation and thus cannot be compared 1:1.

... Solar in winter then also does not help due to lack of sun.

But at least it reduces electricity consumption in summer.