The fully automatic Sigma rainwater unit for supplying a detached house with rainwater.

It extracts rainwater from a storage tank and feeds it under pressure into the rainwater pipe network. The device controls the entire rainwater system, monitors the filling level of the storage tank and automatically switches over to the use of tap water if necessary.

Complies with DIN 1989 and DIN EN 1717.

Dimensions of the Sigma wall-mounted unit (in mm): W 500 x H 510 x D 315

Scope of delivery

  • Aspri Plus self-priming pump, optionally with 3 or 4 bar system pressure
  • Zeta 02 automatic switch with pressure gauge for pressure display
  • Integrated 9-litre make-up tank
  • Cover bonnet
  • Float switch for controlling the drinking water make-up, cable length 15 metres
  • Labelling set

The installation and operating instructions for this product are only available in German and English. With your purchase you agree to this.

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Once your order has been placed, you will receive a confirmation email informing you that our shipping team has received your order. Once your order has been processed, you will receive an email notification with your tracking information. Shipping costs will not be refunded in the event of a return. We ship with:

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Structure and field of application

The SIGMA rainwater unit is ideally suited for use in single-family homes , as almost all components are combined in a single housing. This includes the economical ZETA 02 pump controller, the suction and pressure pump and the mains water top up. Thanks to its compact design, the SIGMA rainwater unit is particularly easy to install , typically in the house service room. The integrated display allows to read the pressure in the rainwater pipe system.

How it works

The SIGMA rainwater unit draws rainwater from the cistern and generates the necessary pressure in the rainwater pipe network. When the tapping points are closed, the pump in the SIGMA switches off automatically after a short time. However, as soon as a tapping point is opened or the toilet is flushed and a pressure drop is thus detected, the pump controller immediately switches the pump on again. As soon as all tapping points are closed and the line pressure rises again, the pump switches off again automatically .

Combined suction and pressure pump

The SIGMA rainwater unit has a combined suction and pressure pump. With this, it draws water from the cistern and pumps it under pressure to the consumers. Up to 66 l/min are conveyed by the SIGMA rainwater unit. The maximum delivery height is 34 m for Sigma 3 or 45 m for Sigma 4.

Uninterrupted water supply

If, in a period of dry weather , the Rainwater tank should become empty, the system automatically switches to mains water operation, with the float switch in the cistern serving as a sensor . If necessary, the SIGMA rainwater unit can also be switched manually to mains water mode . In addition, a small intermediate storage tank in the rainwater unit ensures an uninterrupted water supply in the rainwater pipe network at all times.

Up to 97 % more economical than other rainwater harvesting systems in standby mode.

The controls of many rainwater units have a power consumption of up to 15 watts in standby mode , which accounts for most of the energy required for rainwater utilisation. With the efficient ZETA 02 pump controller, developed in cooperation with the Technical University of Hesse, THM, the standby consumption is reduced to less than 0.2 watts. This means energy savings of up to 97 % compared to conventional rainwater units. The ZETA 02 is included as standard in the SIGMA rainwater works

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Article number

SIGMA 3 without level indicator RZ 1003
SIGMA 4 without level indicator RZ 1004

Technical data

Pump in wall unit Aspri Plus 15/3 Aspri Plus 15/4
Pump controller Zeta 02
Hydraulic data
Operating pressure 3,3 bar 4,4 bar
Flow rate max 65 l/min 65 l/min
Switch-on pressure of the rainwater unit 1.5 bar
min. Switch-off pressure of the rainwater unit 2.2 bar
Maximum start-up frequency 20 times per hour
Pumped media Filtered rainwater, mains water (no sand content)
Intermediate storage capacity 9l
Electrical data
Max power consumption 608W 808W
Power consumption standby < 0,2 W
Mains connection 230 V, 50 Hz, single-phase
Rated current 2,7 A 3,5 A
SIGMA mains cable (pump controller) 1.4 m, with plug (3 x 1 mm²)
Float switch 15 m, free cable end (3 x 1 mm²)
Water connections of the rainwater unit
Inlet from cistern 1" outside thread
Output to the consumers 1" outside thread
mains water connection ³/₄" outside thread
Noise emission
Rainwater operation 45 dB (A) 47 dB (A)
Mains water mode 63 dB (A) 63 dB (A)
Ambient conditions
Max. water temperature 35° C
max. ambient temperature 40° C
Wall unit (width x depth x height) 500 mm x 315 mm x 510 mm