• For requirements of large or high buildings
  • Dual-pump booster
  • Commercial buildings, schools, hotels or industrial premises


For commercial buildings, schools, hotels and industrial premises. The Delta rainwater unit is WISY‘s dual-pump booster system which is designed to meet the requirements of large-scale consumers. It is primarily intended for installation in public buildings and in large or high buildings. The system is capable of supplying a large number of appliances when requirements are extremely diverse.

It is designed according to the modular principle. In order to select the correct modules, it is necessary to know how much water will be required and at what pressure. In larger buildings, these values are generally calculated by a specialist planner. Once this information is known, a suitable WISY dual-pump booster system can be assembled from the following modules:

The buffer tank is also used to draw water from the mains supply when the rainwater storage tank is empty. A fully automatic, electronic control system detects the fill levels in the buffer and storage tanks. The electronic control system then starts up either the pump in the storage tank or the mains water top-up and shuts the system down again automatically when a predefined fill level is reached.

The correct size of mains water top-up can be selected from the table below based on water usage requirements. The unit is supplied ready-assembled on the buffer tank. The electronic control system of the buffer tank starts up and shuts down the mains water top-up when required. It comprises a stainless-steel tundish with nozzle for splash-free inflow, solenoid valve with connecting cable and electric plug, connecting tube with stainless-steel braiding and brass ball valve with stainless-steel dirt trap (mesh size 0.65 mm (0.03 in)).

The dual-pump dual-pump booster must be selected according to pressure and flow rate requirements
and the desired ease of operation.

The submersible pump is module 4 of the Delta rainwater unit. The required size of
submersible pump in the storage tank is determined according to the height differential and the distance between the storage tank and the buffer tank.