The pump is a Reich Power Plus submersible pump, sourced from the caravan and motorhome supply sector rather than the irrigation or garden market. This was a deliberate choice driven by three requirements: low-voltage DC operation, sufficient head for the installation, and compact form factor for tank mounting.
Pump Specifications
| Parameter | Value |
|---|---|
| Flow rate | 19 l/min (max) |
| Pressure | 1.1 bar (max) |
| Operating voltage | 12V DC |
| Power consumption | 45 W |
| Max head | 11 m |
| Diameter | 45 mm |
| Seal | Longlife high-tech seal with grease reservoir |
| Auto-venting | Yes – delivers flow immediately on start |
Selection Rationale
The key constraints were:
Low voltage: Mains-powered pumps were ruled out for safety reasons given the proximity of water and electronics. A 12V submersible pump running off the same supply as the ESP was the cleanest solution.
Delivery head: The drippers are located at approximately 2 m above the pump in the tank. The pump needs to overcome this static head plus friction losses in the pipework. At 11 m maximum head, the Reich pump has substantial margin above the 2 m installation requirement.
Minimum pressure at the drippers: The pressure-compensating Claber drippers are rated at 4 l/h at 1.5 bar operating pressure. The pump’s maximum pressure of 1.1 bar is nominally below this figure – however in practice this is not an issue. The distribution pipe is a closed-end system: the pump pushes against a sealed pipe with no outlet other than the drippers themselves. Pressure therefore builds in the pipe until it equalises at the resistance of the drippers, regardless of the pump’s rated maximum. The system delivers consistent flow across all drippers in practice.
Form factor: The pump must be narrow enough to pass through the tank lid opening — a practical constraint that is worth verifying before purchase, as it determines whether the pump can be installed and serviced without disassembling the tank. The Reich Power Plus fits through the standard lid aperture of the 85-litre flat tank without modification.
Mounting & Installation Notes
The pump is suspended from the tank lid on a short elastic band rather than resting on the tank floor. It decouples the pump vibration from the tank body, reducing transmitted noise.
One further modification was necessary after initial testing: the non-return valve was removed. With the valve in place, residual pressure in the closed-end pipe system had no path to dissipate after the pump switched off. This caused the drippers to continue releasing pressure slowly over several minutes, producing a persistent whistling noise at each dripper. Removing the non-return valve allows the system pressure to equalise immediately when the pump stops, eliminating most of the noise. The minor consequence – that the pipe drains back slightly between watering cycles – is of no practical significance for the wall’s operation.