Wiring a 4channel Zigbee Dry Contact Relay to Sprinkler Solenoid Valves

Hardware
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I have an irrigation system that uses a traditional Rain Bird ESP-Si controller with 6 stations. I live in the US.

I would like to replace the Rain Bird controller with 2 of the 4channel Zigbee Dry Contact Relays (ZG-003-RF) and program it using HA for all my irrigation needs.

I was able to find a European wiring guide here 4 line irrigation control via ZigBee and Home Assistant | EMCU-HomeAutomation.org

I figured that I would adapt it to the US irrigation system.

Would anybody be able to confirm that this is the correct wiring guide for my use case? Any changes to it?

Also, this wiring guide doesn’t mention a fuse. Would I need a fuse? If so, which specific fuse would I need to buy at a local big box store and how would I wire it? I’m totally lost after looking at fuses.

Thank you in advance for your help.

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The only thing I note is that the picture show 12 volts dc for driving the system, and in the US its 24vac including the solenoids for controlling the zones

It would be more helpful to see the specs for the actual board you’re looking at.

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61n1BoOM69L.AC_UF1000,1000_QL80
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This is the actual board

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You should be fine. You may want to replace the 24Vac transformer from your existing rainbird unit as that is the part that typically fails.

FWIW I went through several years of doing my own sprinkler system programming with a couple of relay boards, and I was never able to get as good results (everything green + minimal water used) as using a dedicated Rachio or RainMachine sprinkler controller with built in weather forecast monitoring and adaptive zone times for the seasons. But maybe there’s a sprinkler integration here that does that.

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Looking at the plumbing aspect - what a mess of hose connections that ‘european solution’ suggests! The cost! The risk of one of them popping out and causing a flood is high. Even the diagram in the user manual from Rainbird is far better. Please look it up before you go any further.

If you want to make it a robust plumbing installation, replace the tap with a valve for maintenance shutoff purposes, connect the output to 6 way manifold using pipe, not hose, and connect your solenoids directly into the manifold. The master control valve is optional - you turn it on at the same time as any of the other solenoids.
Depending on your water flow requirements, select the appropriate sized fittings. You can go up in size if they are cheaper, but shouldn’t go down as your water flow rate will suffer.

Back to the controller. The global industry standard is 24volts AC for low voltage watering systems. That is what your existing Rainbird system is using. I’m assuming your existing Rainbird power supply transformer and solenoid water valves are still functional, If not, any generic irrigation 24V AC one will do - you don’t have to stick with Rainbird parts.

The easiest path for you may to retain all your existing plumbing, your existing Rainbird 24V AC transformer, and just disconnect the existing wires from the Rainbird controller and connect them to a cheap 8 port (just ignore the unwanted channels) Arduino style relay board and control that with an ESP32 board, whether WiFi, ZigBee, or Matter/Thread (depending on the ESP model) via ESPHome, and use an existing sprinkler integration in HomeAssistant to solve your immediate problem.

A fuse is a protective device in case of overload. Most sprinkler system transformers are quite robust. Fitting one at the same rating as your transformer output will provide protection. Just connect it in line with one of the two AC output lines coming from the transformer and it will blow if there is an overload or short in the wiring. Some transformers, particularly switching ones, are designed to sustain a short or overload for extended periods, so a fuse can be superfluous.

Cheating and using the existing sprinkler transformer 24V AC to power your ESP32 and relay board may involve a small stepdown power supply regulator, or you could just use a seperate wall wart or cheap cell phone power supply to power that side of things. One rated at 5V 2Amps DC should be more than adequate for both the ESP and 8 port 5V relay board. You may even find a board that has the power supply, ESP and relays all in one. (That is basically what your Rainbird is anyway)

Whatever route you take, keep in mind that water and electricity don’t mix. Keep all your electrical stuff inside a waterproof enclosure or keep it inside and just run the low voltage wires to the water solenoids.

Your local plumbing supply store can often be a wonderful store of hints and ideas on the plumbing aspects, and also on how to calculate what sprinklers and drippers can be connected to each channel. Even browsing some of the other popular sprinkler system designs online from other vendors will soon show you they basically follow the same principles, the differentiation being ease of use and control, something you are giving over to HomeAssistant.

Please advise on progress or if you have any questions.

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Yes, the plumbing aspect should be US standard and no changes to what I currently have. Already 6 functional outside solenoid water valves with underground pipes, electrical wires running to the 24volt AC indoor Rain Bird controller.

I’m only looking to replace the Rain Bird controller with 2 smart relays, each has 4 channels; reusing everything else including the Rain Bird 24V AC transformer.

I would like to use an automotive fuse because it is easy to find and cheap. But automotive fuses are all rated for 12V DC. Is there anyway I can use them for this purpose of 24V AC? Or I need to find one that is specifically rated exactly for 24V AC? Should the fuse be to protect the board or the solenoid water valves or both?

I will power the relay boards using USB 5V 2Amps DC.

I will definitely update on the progress. Thank you so much!

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The 24VAC transformer from my existing Rain Bird unit has been working fine for more than a decade. Did you mean that this transformer would typically fail when I reuse it in the smart relay boards?

Interesting. It definitely takes a lot more time to experiment with the logic to get good results while the dedicated Rachio or RainMachine controllers have been more professionally designed for this. Thanks to your suggestion, I will try to look for a sprinkler integration. (I can’t go back to selecting a dedicated controller because I can’t return these smart relays :sweat_smile:)

I plan to also add soil moisture sensors to the system. Do you think it would make a big difference? Or no need?

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Kincony has a 8 channel ESP32 board.

I have used one of their boards to inetrgrate a heatpump with Modbus into HA.

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Transformers have a useful life and eventuallyfail. The suggestion was a “while you’re at it” kind of thing. I would do it.

When I was coding my own sprinkler system, I went to the turf management school website for Michigan State. They provided details and recommendations based on soil, sun and shade, etc.

When I got a rainmachine, all of that data was helpful setting it up by zone.

The big thing the rainmachine did was cut back on water usage. My water is expensive and the savings were incredible while keeping things green

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Thanks to your insight on dedicated controllers vs DIY, I looked up Rachio 3 and found a used 8-zone unit for $34 tax and shipping included. I ordered it right away as it’s much cheaper than my DIY components’ costs and tinkering time. Waiting for the controller to arrive in a few days and will update. :+1:

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Yes, reinventing the wheel, just because you can, is not always the most efficient method.

There already is a Rachio integration in HomeAssistant.

When your Rainbird 24V AC transformer gives up the ghost, replace it. Not before - preventative maintenance doesn’t appear to be relevant here as there are no moving parts to wear out. Most are built to last decades, as long as they are used within specifications and kept dry and cool. The transformer doesn’t care if it is supplying power to Rainbird, custom made, or Rachio equipment - as long as it draws 24V AC at less than the rated current, all should be well. When they fail, it is usually abruptly, not fading away, so you will know.

Your local truck parts supplier should have lots of 24V fuses as most trucks run at 24V. AC or DC doesn’t matter. Use it to protect all your equipment should something fail and draw too much current. Both the Rainbird and Rachio transformers are rated for around 1 amp at 24V AC, so should be interchangeable.

You will find something else to use those spare relay boards on, guaranteed! The ones you have look quite versatile. If the Rachio controller comes with its own transformer, the Rainbird one could probably be used to power one of the relay boards directly.

The Rachio rain sensor FAQ may be worth reading.

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