OPTIMA 4 and OPTIMA 5 have two pumps: a submersible pump in the storage tank and a centrifugal pump in the rainwater unit. These deliver up to 65 litres of water per minute to the extraction points. The supply line between the storage tank and the rainwater unit can be up to 25 m in length. In normal operation, both pumps operate together, but when rainwater levels are low and the system needs to be topped up with mains water, the pump in the rainwater unit remains in operation on its own.
If the rainwater in the storage tank runs out during a prolonged dry spell, the system switches automatically to mains water operation. The low water level in the rainwater tank is sensed by the float switch. The rainwater units can also be switched manually to mains water operation at any time. A small top-up tank in the rainwater unit ensures an uninterrupted supply of water from the rainwater circuit.
The control systems of many makes of rainwater unit consume up to 15 watts in standby mode, by day and by night, 365 days of the year. This standby power consumption accounts for a large share of the energy required to operate a rainwater harvesting system. To solve this problem, WISY partnered up with the Mittelhessen University of Applied Sciences to develop the highly efficient ZETA 02 pump controller. This innovative device has reduced standby consumption to below 0.2 watts, a small revolution in its own way. Compared to conventional rainwater units, the ZETA 02 uses 97 % less energy in standby mode. The ZETA 02 is a standard component in all WISY rainwater units.