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Irrigation control – self made, Part 2

On we go!

After I had built the base last year, it was now time to finish the control system.
Reminder:
I had built an ESPEasy based controller, controlled via Domoticz with Hunter valves in the garden, the whole connected to 3 taps. However, the irrigation was far from complete, of the total 10 valves just 4 were active.

I have now expanded the control as such, so that I can control 10 valves at all. Up to now I had connected two 4 relay blocks, with which it became already very narrow in the distribution box. Since three relay blocks definitely did not fit into the small distributor, I first got myself a larger, double-row distributor. So that the relay blocks and also the board with the ESP and MCP do not fly around loose in the box, I printed small holders for DIN rails. I found the holders on Thingiverse (-> Link). To screw the relay blocks you need M2 screws, bigger screws don’t fit into the holders.
Since I was already soldering, I also added cables to the remaining I/O ports of the MCP – who knows what I will come up with in the future. The whole thing then neatly screwed in the distribution box, freshly wired and already comes out something like this:

Lucky me the pluggable 12-pin luster terminal is just right for me.
I have two cable harnesses from the basement to the garden, so I need:
(I write “plus” and “minus”, although there is not actually with alternating current)

  • 4 plus poles and 1 minus pole for string 1
  • 6 plus poles and 1 minus pole for string 2

Important safety note:

To avoid overloading the 110V/230V ->24VAC power supply, it must be fused! If I am not totally wrong, this is even a regulation here in germany. I have clamped a slow-blow 0.8A fuse between the power supply and the relay. Slow because of that, so that it doesn’t burn out immediately, if the inrush current is higher for a short time.

The whole in detail:

Pictures of the valve boxes in the garden will follow.

Tips:

If you know that you want to control more than 4 valves, then you may buy 8 or 16 (needs extra 12V supply) relay blocks. If you don’t feel like soldering, you can also buy ready-made boards, i.e. an ESP together with up to 4 relays. But for more than 4 relays I haven’t found any ready made modules yet. If more than 4 valves shall be switched on at the same time, then a bigger 24V power supply is necessary.
To extend the connection cables of the central valves at the water taps or to connect them with the distributors in the Gardenaboxes, I use 2-pole connectors as known from the car sector: cheap, IP67 certified and therefore waterproof.

I took the Hunter valves for the following reasons:

  • 24VAC is standard
  • 1″ female thread fits perfectly to the Garden valve boxes or, strictly speaking, are absolutely necessary for them
  • the valves can be opened manually if necessary
  • in case of power loss they close automatically
  • you could also adjust the flow rate if needed (manually, not by control)
  • Hunter valves have a good reputation and are even cheaper than most others on the market (25 Euro for Hunter vs. 40 Euro for Gardena)

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