2nd Gen sharing a pump start relay with a Hunter Controller?

I have 2nd Gen controller running a well pump via a Hunter pump start relay. Also connected to the pump start relay is my neighbor’s Hunter Pro C controller. We share the well…

Their sprinkler guy said my 2nd Gen is causing an error on their system when both are hooked up. With only one controller hooked up, each works fine. When their controller comes on, the pump start relay cycles on-off very quickly several times before the Hunter Controller errors out.

Is there a pump start relay that will work with both controllers that you know of?


@kcheek - I believe the issue is mixing AC power coming from two different systems.

Two solutions -

  1. http://support.rachio.com/article/145-how-do-i-wire-one-master-valve-to-two-controllers

  2. I believe two single pole single throw normally open relays that operate at 24VAC (SPST NO 24VAC) will solve the problem ($6.00). As an example -> http://www.ebay.com/itm/MAGNECRAFT-9AS1A52-24-Enclosed-Power-Relay-30A-24VAC-SPST-/331304146239

Here’s how I’d wire it up.

Rachio M terminal to one side of the coil to activate the relay on relay 1.
Rachio C terminal to the other side of the coil connected to Rachio M/V on relay 1.
Rachio SC (yes, Sensor Common - @Gene determined it has power relative to the C(ommon) terminal) to one side of the Single Pole terminals on relay 1 and relay 2.
Hunter pump start relay to the other side of the Single Pole terminals on relay 1 and relay 2.

Hunter Pro C MV terminal to one side of the coil to activate the relay on relay 2.
Hunter Pro C Com(mon) terminal to the other side of the coil connected to the Hunter Pro C MV on relay 2.

This way the pump start relay is always powered by the Rachio and there is no mixing of common or current between the two systems. The two systems are also electrically isolated so if there is over voltage on one circuit it probably won’t impact the other circuit unless it jumps from the coil to the pole inside the relay (doubtful).

Standard disclaimers - I’m not an electrician and I don’t know the electrical code where you live. “Your mileage may vary”.


What @DLane described should work. As an alternative, you can use two independent pump relays connected in parallel:

Edit: As @DLane rightfully pointed out to me, it is possible to short circuit your pump / breaker if you are not careful about making sure that relays are truly installed parallel to each other, rather then in a cross-over configuration. After installation (before turning on the breakers), make sure to activate both relays at the same time and use an Ohm meter to make sure that the pump (and thus the breaker) is not shorted. The measurement can be made across any of the inputs or outputs of any of the relays (as long as they are both active).

I recommend you make twist connects internally. You can also mix the pump relays (they don’t both have to be hunter) so you can use a cheaper Orbit relay like this one (link)


Thank you both. Now on to acquiring the parts and making the addition!

EDIT: DLane, do you think the single pole relay for the Hunter Controller should be by the controller or can it be in my garage? The Hunter Controller is near my neighbors deck.

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@kcheek - The relay can be by the Rachio. That will be shorter distance with all the wires involved. The distance isn’t a problem, just like a solenoid on a sprinkler valve.

While PM’ing with @Gene on this he figured that one Single Pole Double Throw (SPDT) relay would also do the trick instead of two Single Pole Singe Throw (SPST) relays. In this configuration, M (Master Valve/Pump) terminal from the Rachio would need to be connected to NC (Normally Closed) terminal, SC (Sensor Common) terminal from the Rachio to NO (Normally Open) terminal and the pump relay feed-line connected to COM terminal of the SPDT relay, control coil would be driven directly by the Hunter controller (Com on one side and P/MV on the other side). In this configuration the pump start relay would be controlled by the Rachio M terminal as circuit is normally connected. When the Hunter controller requests water it will swing the relay to the NO side and to power the pump start relay using the Rachio SC power. In this configuration there would be a slight break (milliseconds) in signal power to the pump start relay if both controllers were calling for water as the relay switched from the NC to the NO position. I don’t think that should be a problem.

Now we’re probably really confused you with four different ways to solve the problem.

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@DLane is giving me too much credit, it was collaborative effort. :+1:

@kcheek where is the pump relay now? It is closer to you or your neighbour?
You also may have an easier time finding DPDT relays (they are more common), like this one (link). One of the contacts will be unused, but that does not effect anything.

@Gene, everything is in my garage, except neighbor’s controller.

Here’s an image of what I have now:

As @DLane has already outlined your best bet is to use one Dual Throw relay, it does not matter if it is a Single Pole (SPDT) or Dual Pole (DPDT), though for 24VAC DPDT relays are more common.

Here is a visual schematic of how one DPDT relay can be used to control your pump relay:

Note that wires shown going into the hunter pump relay are connected to control wires (polarity does not matter), not the pump terminals.

Schematic is drawn so that relay orientation has pins 7 and 8 at the bottom. In this case I’ve used this relay (link), though if you ended up using a different relay, just follow @DLane’s instructions and you should be alright.

Let us know how it will all turn out.


P.S. For anyone else joining us, this solutions does not require that a second controller be a hunter controller. It will just as well work between two rachio controllers or in combination with controller from any other manufacturer (as long a they use 24V AC power supplies). This is a significantly more affordable solution when compared to the official how-to article (link).

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Y’all are awesome! In looking at the schematics, it looks as though I don’t have to mess with the power coming to the pump start our controllers, correct?

If that’s the case I will take early next week with the $8 option. Section hiking the AT Thursday through Sunday:

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:scream: Jealous!

Okay guys, I am about to wire up the DPDT relay and want to make sure I am clear on the wiring. Here is a picture of my pump start relay wiring and Gene’s schematic with the wires from the pump start wiring image.

Do I have it right?


Almost :wink:

The white W wire (rachio common) will connect to one of the yellow lines, the other yellow line will connect to the relay as per your interpretation of the schematic.

What you are missing is a wire from Rachio SC terminal (you didn’t need it before and it should be added), on your markup you have that relay terminal marked incorrectly as to be connected to the white W wire (which connects to Common, not SC terminal).

Everything else looks good.

Thanks Gene. I am doing something wrong with the wiring below. When I turn on a zone on the Rachio, the pump start makes a loud click, pump come on and sprinklers run. When I turn on a zone on the Hunter, there is a faint click and the red light comes on on the DP relay. Any ideas what I’ve got wrong?

I would doublecheck SC connections on rachio side and the relay side. Can you take a picture of your Rachio’s terminals?

That’s it! When I was taking a picture of the Rachio wiring I got close enough that these blind, old eyes could see the lettering on the terminal. I had the White going to S1 instead of the SC.

Switched and the pump start triggered and pump is running.

Thanks again Gene and all!!


One last question. Should I be concerned that the red light doesn’t come on when my Rachio is running, but does come on when my neighbor’s Hunter is running?

Not at all, think of it as a feature. When the light is ON, that means that your neighbour is using the pump relay, otherwise your Rachio is in charge.

The light simply indicates that NO terminal is active (thus connecting your SC terminal to the pump relay, thereby turning it ON), otherwise (when the light is off) it is NC terminal that is active (thus connecting your M terminal to the relay, allowing Rachio to control the relay).


P.S. Your neighbour can only turn ON the pump relay, there is no way this control scheme can prevent the pump relay from being active when your Rachio needs it. Visa versa is also true, short of your power being OFF, your neighbour can turn on the relay no matter what your rachio is doing.

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I have two 3rd generations systems that formally had Hunter and Irrtrol clocks. They shared a pump start, but with the Rachio that setup is not working. One controller is toward the front of the house (has pump start relay connection and is working) and the other controller is located in a shed in the backyard (not working due to being tied in with other Rachio). Would the above setup suggestions work the same for the 3rd gen Rachios?

@jasonholder yes, the only difference is that you would use “24V-” terminal instead of SC terminal shown on the wiring diagram.

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