What kind of instant water heater has stable performance?

Instant electric water heater can't keep up with the hot water quantity, and its power is too high, generally about 8000 watts. The wires at home can't bear it, so I personally don't like it. Anyway, my family is using Sophia integrated water heater now. The trouble with instant electric water heaters in China is that they have never come into contact with this industry. The domestic water heater industry has long been ahead of foreign countries, and domestic consumers have not yet popularized it! Instant electric water heaters like Jiayuan and Autran are very mature! Stiehl instant water heater, with water supply, water cut-off and power cut-off, adopts 99.99% patent of red copper heating system and German core, with high thermal efficiency, dry burning prevention, safety, stability, scale prevention and long service life.