Any irrigation system with a conventional irrigation controller can be upgraded to an unpowered system where each solenoid valve is replaced by an Unpowered Wicking Valve. The conventional irrigation controller and the associated wiring become redundant.
 
The Unpowered Wicking Valve has a standard one inch (25 mm) inlet and outlet. It is also available with a 40 mm inlet and outlet (contact Measured Irrigation for a quote).
 
It is assumed the same drippers are used throughout the irrigation application. 
 
This amazing invention lets you set the volume of water discharged by each dripper or sprinkler during the irrigation event. The dripper discharge is independent of the flow rate of the drippers (pressure compensating or non pressure compensating). The dripper or sprinkler discharge is independent of the water supply pressure.
 
The Unpowered Wicking Valve uses onsite weather conditions to control irrigation scheduling rather than the static timer intervals in conventional devices.
 
After irrigation and as water evaporates from the soil, water also evaporates from the container. The water in the container eventually reaches a low level corresponding to the soil drying out. The valve opens and irrigation begins. A dripper attached to the irrigation system refills the container during the irrigation. When the water in the container reaches a high level corresponding to the required watering of the plants, the valve shuts off and the cycle restarts.
 
Once correctly calibrated, the Unpowered Wicking Valve only sends water when plants need it and does not overwater. It responds to the same local weather conditions as the soil. Deep or shallow watering, frequent or delayed watering – all can be accommodated. You don’t have to ‘turn it off’ over winter as rain and cooler temperatures keep the container from drying out. You can leave your irrigation system unattended for weeks on end.
 
A polyester cloth wicks water from inside the container to outside the container to evaporate and so the cloth is always wet.
 
The Unpowered Wicking Valve has flow control so that the flow can be adjusted to suit the pressure limitations of the irrigation system. For example, if you prefer not to use hose clamps on barbed fittings, you can use the flow control to reduce the pressure accordingly. 
 
KEY FEATURES
Unpowered (no batteries, no wires, no solar panels, no electronics, no computers, and no WiFi)
If you upgrade to the Unpowered Wicking Valve, the conventional irrigation controller, the associated wiring and the solenoid valve become redundant
Use with PC (pressure compensating) drippers or NPC (non pressure compensating) drippers
25 mm inlet and outlet (40 mm also available)
Operating pressure range 70 – 1034 kPa
Set the dripper discharge to any value between 200 mL and 2 L by adjusting the float
The dripper discharge is independent of the flow rate of the drippers
The dripper or sprinkler discharge is independent of the water supply pressure
Adjust the interval between irrigation events by adjusting the exposed surface area of the polyester cloth
Responds automatically to onsite evaporation and rainfall
The irrigation frequency increases significantly during a heat wave
When it rains, water enters the container and delays the start of the next irrigation event
Water in the container is protected from debris, algae, mosquitoes and thirsty animals
Simple, unpowered, and low tech, and therefore fewer things can go wrong
Leave your irrigation application unattended for weeks on end