There is two type electric water heaters: Instant electric water heaters and storage electric water heaters, and the variable frequency constant temperature electric water heaters we talk is the instant electric water heaters.

At the beginning of research and development, instant electric water heater manufacturers started from the aspects of safety, energy saving and environmental protection. The instant electric water heater can quickly discharge hot water because of its high power, but in order to make the water heater energy-saving, it developed an "intelligent frequency conversion" .The function allows the water heater to automatically adjust the working power according to the cold water temperature, the water flow rate and the set temperature. So it does not always work at the rated power. And it can discharge hot water immediately, so it is more practical.

For the storage electric water heaters, they are all rated power. Since the power is less than or equal to 3KW, it takes a long time to heat the water, so it is no need to make a frequency conversion.

Therefore, the instant electric water heater has an intelligent frequency conversion constant temperature function, while the storage electric water heater does not have such a function.