Controlling multiple valves with one channel

I need to control several valves with a single channel, since related plantings are physically too far apart to control with a single valve. I have Rachio v2 controllers with supplied transformers. Several channels already drive 2 valves, with no issues. I’m looking to add valves 3 and 4 in a couple of channels.

Does anyone here have experience with 3 or 4 valves per channel?

  • I am aware of the limitations of water pressure - but the multiple valves I’m activating are watering a few trees with dripper loops, with a total of maybe 100 x 0.4gph drippers across 4 valves, which doesn’t even make a dent in the water pressure (it’s capable of running much much bigger channels on this pump).
  • I know that I could just use multiple channels programmed the same, but I’m running out of channels. I’m also running out of time in the day (I’m often watering from 5am to 4pm) - since the drippers are so slow and channels only run sequentially.
  • I know that I could use multiple controllers, but it’s rather non-trivial to have multiple controllers coordinate to turn on the master pump valve. Also I have limited wiring in the garden, so I don’t have enough wires to run 30 or 40 channels (I have 3 cables x 7 wires that gives me 16 channels + common + master + 2 for the water meter + 1 spare).

The details:

I have a master valve that controls a relay that operates a tank pump, which takes 400mA inrush, 200mA steady state. I am using Rainbird CP075 valves which draw about 200mA inrush, 160mA steady state.

I read that the transformers are rated to 1A, which I interpret as having capability for 200mA for the master steady state + 4 x 200ma for 4 valves starting simultaneously. Empirically, I have tested master and 4 valves at once, and the transformer voltage doesn’t drop appreciably (still above 24VAC), and the transformer doesn’t get warm.

I read that Rachio’s switches are rated for 2 valves simultaneously. I have tested 3, and had no problems. I have (accidentally) tested the Rachio with a shorted channel, and note that it shuts down and sends me an email.

I am concerned that at three or four valves, the Rachio may intermittently think it has a short circuit and not reliably operate the channels with more than 2 valves at once.

The alternative is to use a bigger transformer, and use the Rachio to drive relays that are rated to as many valves as I want to drive. Does anyone have experience with using relays such as “Omron G2R-1-E”, or perhaps a rail-mount set like “DIN Rail Mount AC/DC 24V control 16 SPDT 16Amp Pluggable Power Relay Module, G2R-1-E”?

Do you have a master valve in the system?

If not, technically Rachio can run 3, but it is at its limits. That being said, I have 1 zone that I have been too lazy to reconfigure (via piping) and it is 3 valves run by one zone…

I wouldn’t advise a larger transformer as you might cause issues with the board.

1 Like

@neilhunt - Be aware that if the reduce water hammer option is enabled in the system, then the valves on the currently running zone and the next zone will both be active when the next zones starts.

If there is a spare wire in the field wire to where the additional valves are located, I’d make a second common wire and use a SPST relay (low amp draw) in parallel with the existing valve to close the circuit to an additional power supply for those additional valves. The second common wire would also go to the additional power supply. As no wires are shared between the two power supplies one will not need an isolator. If a second common wire isn’t possible, then using an isolator on the commons between the Rachio and the additional power supply with the same SPST relay switching on the power to the additional valves could also work.

Welcome to the community and of course - YMMV.


Thanks. Ingenious solution. Any specific suggestions for a suitable relay?

I hadn’t realized that the channels/zones overlapped for reduce water hammer that’s worth knowing.

@neilhunt - something like either:


I should have mentioned the relay needs to be a NO (normally open) version.

You’re welcome. Glad I could help.