Introduction to the DIY Universal Measured Irrigation Controller Kit
- Variations in the water usage throughout the year are controlled by the prevailing net evaporation rate (evaporation minus rainfall).
- The volume of water discharged by each emitter during an irrigation event is controlled directly without the need to control the flow rate or the duration of the irrigation event.
It is assumed that the irrigation system (either pressurised or gravity feed) for your garden or small plot of land has already been established.The DIY Universal Measured Irrigation Controller Kit is easy to assemble to become a weather-based irrigation controller. It is easy to adjust the water usage and the irrigation frequency.
Instructions for assembling the DIY Universal Measured Irrigation Controller Kit
- Valve assembly with inlet pipe.
- Cylindrical float
- 6 float rings
- Outlet pipe (15mm BSP)
- 2 round plastic nuts (15mm BSP)
- Inlet assembly with 4mm valve
- Float switch assembly with 4mm valve
- Flexible overflow tube
- Adjustable control dripper
- Irrigation control box with light sensor
STEP 1: Choose a suitable evaporator. The evaporator is a plastic container with vertical sides with an opening of at least 20cm x 20cm and a height of at least 15cm (a hobby box is ideal).
STEP 2: Drill two 20mm holes opposite each other in opposite sides of the evaporator. The centres of the holes should be no more than 5cm higher than the
bottom of the evaporator.
STEP 11: Slide the cylindrical float over the float shaft.
STEP 12: Connect the flexible overflow tube to the top of the float shaft.
STEP 13: Connect one of the wires from the float switch assembly to the yellow wire from the control box. Connect the other wire for the from the float switch assembly to the white wire from the control box.
STEP 14: Connect a 12V DC solenoid valve to the water supply for your irrigation system. Connect the blue wire from the control box to one of the wires from the solenoid valve. Connect the green wire from the control box to the other wire from the solenoid wire.
STEP 15: Connect a 12V DC power supply to the red wire (positive) and the black wire (negative) from the control box.
Disconnect the green wire from the 12V DC solenoid valve and connect it to one of the wires from alternative solenoid valve.
Connect the other wire from alternative solenoid valve to one of the wires from the alternative power supply.
Cut the pink wire (connected to the black wire) and reconnect it to the other wire from the alternative power supply.
STEP 16: Connect the outlet from the solenoid valve to the irrigation system.
STEP 17: Connect the adjustable control dripper to the irrigation system and position it so that it drips water into the evaporator during the irrigation. (If the irrigation system uses pressure compensating drippers, replace the adjustable control dripper by a pressure compensating dripper.)
STEP 18: The switch on the control box had 3 positions: ON (switch up), OFF (middle position), and ON night only (switch down). If you are happy for the irrigation to occur at any time of day, then flick the switch up. If you want the irrigation to occur at night time only, then flick the switch down. For the initial setup flick the switch up to the ON position.
How to adjust the water usage for sprinklers and non pressure compensating drippers.
If your plants are not getting enough water, turn the control dripper clockwise to reduce the flow rate of the control dripper.
How to adjust the water usage for pressure compensating drippers.
The water usage is directly proportional to the surface area of evaporation. You can increase the surface area of evaporation by choosing a supplementary evaporator with vertical sides. The total surface area of evaporation is the surface area of the supplementary evaporator plus the surface area of the original evaporator minus the surface area of the float. One way to connect the evaporators is to drill a hole in the side of each evaporator and to insert a rubber grommet into each hole. Insert a barbed connector or elbow into each grommet, and then use a length of flexible tube to connect the evaporators. The water level will be same in both evaporators.
How to adjust the irrigation frequency
The DIY Universal Measured Irrigation Controller Kit includes 6 float rings that can slide over the cylindrical float to increase the outside diameter of the float (the bottom of the float ring should align with the bottom of the cylindrical float).
The following table shows the irrigation frequency for various float rings and anticlockwise turns off the control screw. The irrigation frequency is determined by the net evaporation from the evaporator between irrigation events.
Table 1. Irrigation frequency for the DIY Unpowered Measured Irrigation Controller
Key features of the DIY Universal Measured Irrigation Controller Kit
- Completely automatic.
- Can be used for any size plot.
- Smart irrigation controller – the irrigation is controlled by the prevailing weather conditions rather than a program.
- Use for gravity feed or pressurised irrigation.
- Use for sprinkler or drip irrigation.
- Use for pressure compensating drippers or non pressure compensating drippers.
- You can adjust the water usage by adjusting the control dripper.
- You can adjust the irrigation frequency by changing the float ring or adjusting the control screw.
- The water usage is directly proportional to the net evaporation rate (this is a unique feature of measured irrigation).
- Responds appropriately to an unexpected heat wave.
- When it rains, water enters the evaporator and delays the start of the next irrigation.
- The water usage is independent of the water supply pressure (this is a unique feature of measured irrigation).
- Uses much less water without affecting the yield.
- Simple and low tech and so easy to assemble and fewer things to go wrong.
- Provided you have a continuous water supply, you can leave your irrigation application unattended for weeks on end.