Smart Modification of a Irrigation System




Introduction: Smart Modification of a Irrigation System

Material list:

IP67 Distribution box

24V IP67 Power supply

shelly RGBW2

Step 1: Existing System

Four irrigation circuits with Gardena irrigation
valves 24V (1278-20)

(The picture shows only three of the valves in a valve box. The fourth valve is in a separate box)

Step 2: Electrical Installation:

From Gardena direct there is no smart solution for an irrigation system with valves. Since I've already tried a lot with shellies, I came up with the idea to control the valves with a shelly RGBW2 with four separate channels. The connection is very simple (Fig.1). I housed the shelly RGBW2 in an IP67 junction box (Fig.2) and connected it to a 24V power supply (Fig.4).

The connection of the power supply to the 220V power
supply should be done by an electrician. So please be careful, especially if you are not very familiar with electrical installations !!!

Step 3: Setting Up the Shelly App

1) Set Device Type to 4x white stripes LED, then appear

four separate buttons in the app

2) Set the switch compartment type

3) Set the standard mode Power on to Off, so that the system at

after a brief power failure, the valves do not turn on again.

4) Now the individual channels can still be named

A routine can then be created in the shelly app or in the Alexa app so that the four irrigation circuits are switched on one after the other.

Step 4:

1 Person Made This Project!


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Question 2 years ago on Introduction

You are using 24V AC Gardena valves. But the shelly have an 24V DC output. How is this functioning? Does your system still work? Thank you


Answer 1 year ago

Hi, I guess that your valves are not too far away from the RGBW2 and the DC transformer....but, could happen that in an existing irrigation system built with 24vac there are valves up to 100m or more far away from the "controller"....
Is there no option to use 24vac as Shelly input?
Cos switching to latching valves (9v) will have the same problem regarding loss of power (v)

Dennis WernerF
Dennis WernerF

Answer 2 years ago

While applying 24VDC will control the solenoid inside a sprinkler valve, it comes with the downside of operating at a much higher current. This is covered in depth here:

In short: The setup epxlained above will lead to increased current draw and power dissipation which in effect might shorten the life of the solenoid because of highter operation temperatures. An improvement would be to use 12VDC, or lower the voltage after the initial inrush after power-on, which would require additional circuitry and logic.

The best option would be to switch to DC-Latching valves.