ᐅ It takes a long time for hot water to arrive.

Elina schrieb:

As mentioned, the 600 kWh includes the power consumption of the high-voltage pump.
We would need to calculate exactly how many kWh that is, but since it is a three-phase connection, it probably accounts for a significant part.

Edit: our house has no hot water pipes except those from the tankless water heater to the outlet (1-2 meters (3-6 feet)).
There were also no heating pipes.

You just have an unusually low hot water consumption, and you probably know why. How do you heat your home? Without central heating it’s also a different situation.
If the consumption stays this low, the potential savings are probably too small to justify building a new central system.

Currently, we are still heating with a wood stove. In 2014, we installed a brand-new pellet boiler and a buffer tank. However, it is still not in operation because the necessary heating surfaces are missing. We cannot find a heating engineer who will install and connect the underfloor heating. Nobody takes on jobs under 100 m2 (1,076 sq ft), but I cannot offer that much area.

So, we continue with the wood stove until we install the underfloor heating ourselves. Since I’m not very confident about doing it, that will probably take a few more years.

Before, there were night storage heaters.

To all users of tankless water heaters: how is your hot water comfort? For example, can you fill a bathtub with consistently warm water? What happens if one person is taking a bath while another is doing the dishes, or if multiple outlets require hot water at the same time?

We have been living with a tankless water heater for almost 10 years, and it has been a disaster. Even a new electronic tankless water heater (also from Stiebel Eltron) that we recently installed cannot meet these requirements.

It was installed by a professional who also advised me against using tankless water heaters for hot water supply in the house construction.

We don’t have a bathtub, only showers. If one person is showering and another turns on a faucet, you can definitely notice it. The water pressure drops slightly—not by much, but noticeable. The temperature, however, stays the same.
If it’s that bad on your end, I might consider installing separate point-of-use electric water heaters (under-sink units plugged into an outlet) for the washbasins. Hand-warm water is usually sufficient there.
However, in our case, this effect also occurs when only cold water is turned on. Maybe the supply line is just not properly sized.

Jenpa schrieb:

To all tankless water heater users: how is your hot water comfort? For example, can you fill a bathtub with consistently warm water? What happens if one person is taking a bath while another needs hot water for washing dishes or multiple fixtures require hot water at the same time?

We have lived with a tankless water heater for nearly 10 years and it has been a disaster. Even a new electronically controlled unit (also from Stiebel Eltron) that we recently installed cannot meet the above requirements.
It was installed by a professional who also advised me against using tankless water heating for the house build.

We have a 27kW (approximately 91,500 BTU) tankless water heater from Stiebel Eltron. Filling a bathtub with hot water is not a problem. If you turn on the hand shower at the same time, the water pressure obviously drops. But overall, we are satisfied. Previously, we had a large hot water storage tank mounted in the bathroom. Now we have much more space.

What is the power rating of your tankless water heater?

Kurpfaelzer schrieb:

We have a 27kW (kilowatt) tankless water heater from Stiebel Eltron. Filling the bathtub with hot water is no problem.

That’s not surprising at all. There’s plenty of power, and the temperature of the water flowing through doesn’t change. You could even fill an entire swimming pool with it.
However, it uses a lot of electricity, so it’s uncommon in new builds.