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

I only know what was once overheard in the neighborhood. That the use as living space was prohibited, but I do not know any details. It is also unknown how the building authority found out about it.

By now, I am a fan of asking beforehand and saving oneself trouble afterwards.

As for the comfort: That is true, but whether it stays that way, no one knows. But 70 is not old yet. That is when life really begins. (At least that’s the impression I get when I look at my mother). One could also only use the great stoves when visiting.

Hmm, for us it is already living space, there is only an attic above which I am considering tearing out so that the ceilings become higher. Approval would probably not be necessary in our case, as nothing is being reclassified and the external appearance of the house is not significantly changed.

"Especially the older person surely likes it simple and functional." My mother still enjoys working with wood. So not just heating but also chainsaw + chopping and we already have a wood stove in the kitchen, but you simply cannot rely on that staying the same.

yep and depending on need/size there is also compressed material to buy. You really should make that dependent on the individual requirement

We also planned to install a new heating system in grandma’s house because she heats with night storage heaters, but that is very expensive. On the other hand, if you offset the costs for any kind of new heating system, you can forget it. It won’t "amortize" in 30 years, just as you wrote

A deciding factor besides functionality can always be a person's heating behavior or the residents’ preferences. maybe one does not want to miss a nice wood stove or is glad to be rid of it, both possible. There are people who consume far more energy in modern houses than some older people in their 70s buildings. Often the saying spreads: Savings at any cost!

Long ago, individual oil stoves were used to heat every room, with oil cans.

Ah yes... my youth... with the sulfur strip... and woe if there was too much oil in it... wufffff

As for carrying wood: I wonder how the old farming folks survived.

If an older person can no longer do that, other things are usually already failing for a long time. You can perhaps store it on the floor, at least a sufficient amount, and nowadays wood stoves require significantly less wood than 25 years ago, with a higher efficiency. So we will have a nice wood stove in our new build and I already know that it will more or less run continuously in winter. I don’t calculate that only based on costs, but also on the joy I have from such a fire. In addition, the stove has a substantial storage capacity.

Our idea was to install a photovoltaic system on the roof with a battery / accumulator in the basement and thereby operate new infrared heaters and the water boiler.

Exactly that is what we will implement in our KfW40Plus new build now, and with a domestic water heat pump for the hot water topic, we have found a very good energy consultant. Depending on the situation, electric instantaneous water heaters would also make sense but that always depends on the individual need or situation. Once you seriously deal with it, you suddenly discover things you didn’t know before. There are now renowned architects and institutions here that implement and recommend that for good reason. We will definitely do it that way.

I am currently also reading about water heat pumps. That would free up the chimney for the wood stove in the living room. We have a creek flowing through our property, about 20-30m away from the house. Therefore, I suspect that you wouldn’t have to drill too far down to the groundwater. I think that the creek does not carry enough water to extract the heat directly from the creek, or the distance is too great. Next to the house there is an approximately 2x2.5m waterfall on public land where the municipality now wants to install a fish ladder.

Depending on the situation, electric instantaneous water heaters would also make sense, but as always, it depends on the individual need or the situation.

That really sounds good. You have a new build and have been well advised. I am also very glad that the wiring and fuses for a photovoltaic system were already planned in our house. Unfortunately, our roof is really small and it is not worth it yet. Besides, paying it off first is nice. If the big crash ever comes because of fossil energy and CO2 taxation, we will also upgrade. Until then, I assume the concept is sound and feasible for terraced house roofs. The wood stove is not necessary at the moment, I would like to have one, but it is so warm in here that we would only use it during the transitional seasons. But the topic is not forgotten yet. Unfortunately, we are also not that far yet with grandma’s house planning. The whole thing is still quite confusing. A gas connection is already in the street and would cost 2000 euros to the house. We are also considering simply installing normal radiators and a gas heating system. Someone will surely take over the house later and be happy about the kitchen stove and wood stove, preferably one that stores the heat from the evening and still releases it in the morning. What do you think about that? I am unsettled because of the CO2 tax that is being talked about. We looked at a house in France that has a combined gas-wood heating system. That also sounded interesting. P.S. A long time ago I rented a house with a briquette stove, that was an experience too.

We have a stream flowing through our property, about 20-30m away from the house. That's why I suspect that one wouldn't have to drill too far to reach the groundwater. I think the stream doesn't carry enough water to extract heat directly from it, or the distance is too great. Next to the house there is an approximately 2x 2.5m waterfall on public land where the municipality now wants to install a fish ladder

That sounds very nice, it's a holiday paradise