What to replace an oil heater from 1989 with in an old witch's house?

Where is the big advantage of the monoblock?

Mono - everything including the refrigerant circuit in one device. Anyone can install the device themselves and does not need a technician.

Hmm, with that I would have to lead the water pipes through the house wall to the outside. If the heating then fails and it is winter, I think that would quickly become quite suboptimal?

That is bad with any heating system. But as a backup, the heating element is still available to you. Properly wrap the pipes for the underfloor heating in Armaflex and that way it is well insulated.

Tell me, what is included in 20k for a new oil heating system? That seems SIGNIFICANTLY too expensive to me?

It also seemed quite high to me. But two heating technicians have already given us that amount as a rough reference.

Hmm, I need a technician on site anyway for the new heating system, I can't do it all myself. Efficiency seems to be largely the same for split and mono. At the moment, the split solution seems much more appealing to me, plus the outdoor unit remains smaller and part of the noise pollution is relocated to the basement.

That is complete nonsense. A new burner costs maybe 5k with installation, if something still needs to be done in the chimney (new devices are not hot enough, so a pipe has to be pulled into the chimney) that also costs a bit. But definitely not more than 10k with an existing tank.

Yes, the tanks should be retained. But the chimney must be converted, the old heating system dismantled and disposed of. Although I have noticed that at least the control unit still brings in some money when sold :)

I can imagine that the heating engineers always initially quote a price that is too high in order to undercut it later.

Just think twice for once. I understood you to mean that you would actually prefer to have a stove and later in life want to avoid the work. So put in a stove, upgrade the electrical installation, and lay cables for infrared heaters. When the time comes that the stove is too cumbersome - turn on the infrared and that’s it. That does cost a bit more electricity, but it takes away the worries about "unfit" days and the desired heating works for the coming years.

Interesting approach. However, we already have radiators in the house, and a wood heating system would probably be best in the basement where the oil heating is currently located. This would mean the chimney is then occupied again, and no wood stove would be possible in the living room. Finally, things are moving forward and we now have an appointment with the energy consultant.