Financing / Single-family house purchase with or without renovation

Yes, of course, I agree with you. It will definitely be done, it's just about the principle or rough direction for now.

For a new oil heating system, please also check the tanks. Old ones made of plastic may have exceeded their lifespan.

In general, however (from both an economic and ecological perspective): keep the heating running and only replace it when it is broken. Mine is from the 80s and a replacement would not be worth it. You just need to have some savings set aside...

Hm ok, that is of course also an argument.

As a general rule (from both an economic and ecological perspective): keep the heating running and only replace it when it breaks. Mine is from the 80s and a replacement wouldn't be worthwhile. You just need to have some savings...

That's basically what I would have advised too. If the heating actually gives up the ghost in 5 years and there isn't even €10-15k available, there could be problems..

Yep, leave the heating inside. The replacement would not be nearly as expensive as you estimate. A new condensing boiler should cost somewhere between 5 and 10k. Painting the facade is not cheap because of the scaffolding, but that shouldn't cost €20,000 either... Heating replacement is relatively clean to carry out, no problem even in an occupied state. What I would do instead in your place and also factor into the financing: redo the bathrooms right away. If you already say now that you don't like them but can live with them, that's not a good basis. It will annoy you every day, probably your wife more than you. Renovating bathrooms makes an incredible mess, doing that in an occupied house is impossible to terrible for quality of life. How about the electrical system? The same applies as with the bathrooms, only worse. That is definitely not possible in an occupied house.