The MULTIMAT rainwater unit is designed for use in single-family homes or apartment buildings, but can also operate successfully in small commercial premises. It consists two units: the indoor wall bracket with controller and mains water top-up equipment and the submersible pressure pump with float switch and suction filter in the rainwater storage tank. If one extraction point in the rainwater circuit is opened, the controller detects the pressure drop and switches the pump on. The rainwater is pumped directly from the storage tank to the extraction points. The pressure indicator displays the pressure in the rainwater supply circuit.
Since the pump is located in the storage tank, the indoor installation space required is much smaller than for other systems. There is no audible pump noise. Apart from the sound of flowing water, the indoor system is completely silent.
The rugged Multigo submersible pressure pump can build a pressure of almost 5 bar. It is easily capable of pumping water around multi-storey buildings or through long extraction pipes. As part of the MULTIMAT rainwater unit, it is available in two different versions. The small Multigo 205 pump can deliver 80 l/min, while the larger Multigo 407 can pump up to 125 l/min.
To ensure that the water supply is of the highest possible quality, a floating suction filter is connected upstream of the submersible pump. It is fitted with a fine filter screen with a mesh size of only 0.3 mm. This filter is connected to the pump by a hose and is suspended from a float just 20 cm beneath the water surface. This is exactly the height at which the water is cleanest because heavy particles sink to the tank base, while lighter ones float to the surface.
If the rainwater in the storage tank runs out during a prolonged dry spell, the water reserve in the tank is topped up with mains water. A float switch senses the fill level of the tank. If the water level drops below a minimum limit, the solenoid valve for mains water top-up opens and the water in the storage tank is topped up with enough to meet average daily requirements. This system ensures that an adequate water supply is available at all taps. Thanks to the open outlet, it is impossible for rainwater to come into direct contact with the mains water circuit, so ensuring that the system complies with standards laid down by the German Institute for Standardisation.
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 of the SIGMA rainwater unit.