Instantaneous water heater requires 3-phase power, which is not always available in every apartment. Most new built village houses are equipped with three-phase power, so 3-phase instantaneous water heater can be installed. However, the electricity supply design (single-phase or 3-phase) in an apartment depends on the decision of the developer.
Residents living in apartments with single-phase power can either choose to install a centralised electric water heater with a capacity of about 25-38 litres, or a shower storage type water heater with a capacity of 18 litres.