Instantaneous heaters mostly require a three-phase connection and high permissible loads. Prior to buying a heater of this type, it is important to check whether it can be connected to the existing electricity grid.

There are three important criteria to consider when buying an instantaneous water heater:

1. Number of water consumption points,
2. The total possible water flow rate,
3. Technical possibilities of electricity supply.

• A 7–10 kW instantaneous water heater will allow you to shower comfortably, but for larger consumption, a heater of more than 18 kW is preferable.
• It is recommended to place the instantaneous water heater as close to the point of use as possible. However, if the living area is large and the distance between the water outlets is long, the installation of two separate instantaneous heaters may prove to be more optimal.