Construction costs are currently skyrocketing

So I am also not under any time pressure, since it is a condominium that will initially be rented out (until the end of the fixed interest period in 5 years, and then I'll see how the market is). Finding tenants in Berlin is relatively quick and possible on short notice.

But it is still a nasty double burden. In principle, every additional month costs me 1000 EUR more.
That means if no short-term delivery date is named by the end of January, I will go ahead with the heat pump deal and buy two instantaneous water heaters for hot water.
Dusty work basically won't be necessary anymore; it will only be about heating and hot water – provided the electrician completes his work by the end of the month as promised.

Basically, every month costs me 1,000 euros as well. Plus heating up electrically... So far, I am satisfied with the use of the mobile electric heating unit. Unfortunately, the installation of the 80-liter hot water tank also costs additional money. I am looking for a better solution here. Does it make sense to install an electronic instantaneous water heater? Can this device still be used meaningfully when installing the heat pump?

Sometimes you just have to sweeten the numbers a bit for yourself. You have to pay tax on the rental income, damn, and then it's no longer 1k net ;)

Unfortunately, I have already factored that in (or out). There are plug-in instantaneous water heaters with 3kW, which are sufficient for the hand washbasin and probably also a shower. Of course, you don’t take a hot full bath with them.