It takes a long time for hot water to come

Water pressure reduction is ok, but that suddenly cold water comes out or the tub only gets lukewarm because of it...? I'll check later how many kW the new instantaneous water heater has.

To all tankless water heater users: how is your hot water comfort?

I use one in my apartment for the bathroom. Small device with 21kW. Even the medium setting is enough for me to get hot water continuously (at full power, simply too much cold water has to be mixed in to make it comfortable).
The 400V tankless water heaters usually have a power of 18-27kW and are ALWAYS sufficient for the bathtub. If the toilet is flushed and the pressure changes, there will be less water in the shower or bathtub, but it will be hotter.

The 400V instantaneous water heaters usually have a power of 18-27kW and are ALWAYS sufficient for the bathtub. If the toilet is flushed and the pressure changes, there will be less water in the shower or the tub, but it will be hotter.

That was not the case with my old one, which was also electronic, by the way. Beyond a certain point, only cold water came out. We haven't tried it with the new one, since we don't actually take baths.

That was not the case with my old one, by the way also electronic. After a certain point, only cold water came out.

This can only happen if it is defective. Otherwise, the water simply flows through without temperature changes. No matter how it is regulated.