Different Heating Concepts Compared

- and finally we are talking about a temperature increase for the legionella program from 50 degrees (normal hot water temperature) to 60 degrees. This means that the water must be raised by 10 degrees once a week. With a typical 3 kW heating element, we are thus talking about weekly costs of 50 cents

However, the legionella program must be at 70 degrees, you would know if you had skimmed through the linked document. Be that as it may, if a 3 kW heating element starts up, the 50 cents are used up after 20 minutes.

However, the legionella program must be set to 70 degrees, you would know this if you had skimmed through the linked document.

No, legionella die at 60 degrees.
70 is often recommended just to have some buffer and to also reach 60 degrees in the pipes and faucets.
In a single-family house, this is not necessary because the pipes are sufficiently flushed.

Anyway, when a 3 kW heating element starts up, the 50 cents are spent after 20 minutes.

1 kWh currently costs 30 cents and not 50 cents.
Ideally, you do this with photovoltaic and then you are at 8 cents lost feed-in tariff.

But apart from that, yes, and? Even once a month/week, I still don’t end up with hundreds of euros.

However, the legionella program must be 70 degrees, you would know that if you had skimmed the linked document.
Anyway, if a 3 kW heating element starts up, the 50 cents are used up after 20 minutes.

You don't want to understand. At 50 degrees continuous temperature, 60 degrees legionella program, and regular use of the water, you don't need 70 degrees. Because then you don't have any legionella to kill in the first place. Otherwise, they die at 55/60 degrees, with 70 degrees you are 100% safe.

And yes, you only need the 20 minutes. The heating element doesn't take longer to increase from 50 to 60 degrees. And if it is 30 minutes at 35 cents electricity price, it is still under 50 cents (photovoltaics cheaper).

From a scientific treatise (RKI) - legionella like it cool to warm in stagnant and rotting pipes, they hate very warm and flowing water:

Everyone can of course have their 60, 80, 100, oh what, straight 150 degrees flow temperature with the corresponding pressure. Their own nuclear reactor in the basement. Currently, it is simply easy to get uranium in Niger, so just take a class trip and cobble together a nice system.

Seriously now: Nutshell, you want a system that moves miles beyond any normality. You are sincerely entitled to that, but for that you don’t need to ask a specialist for advice.

Well, when I go on vacation I'd rather keep it at 60 degrees.

No water is used during vacation, so the pipes reach room temperature. According to your statement, there is no danger even at 20 degrees. Accordingly, I would rather turn off the hot water (there are now ways to turn it back on according to the return, both by timer and via the Internet). Then you set it once to 70 degrees and let warm water run everywhere for 5 minutes upon return. I wouldn't even think of keeping hot water at 60 degrees for 3 weeks...

How much does it cost to heat plus hot water with an air-to-water heat pump + underfloor heating in a kfw55 house with around 130sqm? So in euros, per year, actual and not "calculated"