Adding an external switch to turn on well pump without running a zone

I replaced my Nelson Smartzone EZ controller with a Rachio 3 controller. On my Nelson controller I had an external switch wired to controller to which allowed me to turn well pump on manually, without running a zone. This is needed because well is used for irrigation and to fill the pool. In the Nelson controller the switch was wired to the M/P port and to a port labelled HOTSPOT. Therefore the M/P port had 2 wires to it, the switch wire and the wire going to the well pump relay.

How do I wire the switch to the Rachio controller.

I am thinking wiring one wire to the M/P port of the Rachio controller and the other to the +24 port.

Am I correct?

Are you using all of the zones within your controller? If not, you can designate any of the unused zones as a pump only zone. This of course would not work with index valve, only systems with individual zone control.

I know that…but that doesnt work in what I am looking to do.

The switch is needed for pool guy to fill pool or top it off. The controller is not accessible by him.

Question still stands, how to wire switch to engage well pump on demand.

I’m not sure I understand the setup here…but are you saying that you have a switch that turns the pump on, and you say that switch somehow ran through your old controller?

The 24vac port would be to power a sensor or something. It certainly could power a relay I suppose, but I’m not sure how it could be used to power a relay THROUGH a switch…

Yes, exactly.

That switch created a circuit which was always 24VAC, even with no zone running. That allowed for manually turning on the well pump, for multiple use of well water.

I had an interesting thought that probably will work. I would like others to confirm.

As you have now:
C directly to relay for pump
M directly to relay for pump

24VAC+ —> switch —> M

Switch off would drive the relay directly from M
Switch on would drive the relay through 24VAC+
If both M and switch are on, it should be the identical power, so should not cause any problem

To be safe, I would double check the power of both 24VAC+ and M to make sure they are the same.
Definitely, one can add something to keep both from coming on as needed.

That is what I was thinking. What I am not sure of is if the 24VAC+ is always hot. I believe that it needs to be to power the wireless devices it was intended to power (i.e. wireless rain sensor). Correct?

Yes, I have only heard of it being used for powering a sensor, but maybe others have used it for other things.

The big question is if those are the same power, which I do not know how to test. If someone has opened up the controller and looked at that or at a schematic, they might be able to tell. I would be kind of afraid to try without more research. I sure it can be protected with other electronic components, but not the best at this part.

I think you would want M out of the switch equation. Run M directly to the relay. When Rachio fires up, it will power the relay as you would expect.

Run 24vac+ to the line side of switch, and relay to load side. When switch is off, no power to relay, and M should function as normal. Flip the switch and power should flow to relay.

My only concern would be some sort of power feedback to M terminal? @Gene, do you think that would cause an issue?

Common is at 24v+, so you’d need to add a switch from 24v- to M to activate the relay connected there. I do not expect it to generate an error.

Thank you @tmcgahey for tagging @Gene. Since he wants M still working, but a manual switch, I would think having the other side of the switch connected to M would be the same as two wires to the relay (or maybe I misunderstood you).

@Gene: Oh, really? I am glad you jumped in here! So, 24VAC+ is equivalent to C and the zones/M are equivalent to 24VAC-? Would that not give 48VAC differential (similar to 120V single phase vs 240V dual phase)?

Adding to my original thought, a SPDT switch might work out even better. Have the center running to the relay and then one side to ‘M’ and the other to the always on power. When switched one way, ‘M’ controls the relay and the other would always turn on.

I think we are getting something confused here…the C is not +24VAC. It is -24VAC.

Each port 1-12 (depending which controller you have) on the controller send positive voltage, +24VAC.

I look forward to seeing what @Gene says

Ages ago, I thought that C was "-"ve too, discovered that it was a positive with active zones being “pulled down” so to speak to a negative terminal.
Rachio does the sensing at the "-"ve terminal, low side as far as we can label it. Controller activates a zone by connecting it to the bus with the sensors, thereby allowing the controller to measure power consumption and indicate a faulty valve for example.C terminal is thereby connected to the opposite bus, "+"ve in this case.
AC voltage does not have a positive or negative and rachio uses a single phase power supply, “+” and “-” here are simply to indicate power “+” and sensor “-” buses.

Edit: To properly measure AC voltage (which doesn’t have + or - in itself), you should measure from active zone to +ve terminal (this should give you full ~24VAC) and -ve (close to 0)

Ok…so let me ask the question again but will retweak the verbiage.

If I wanted to engage the well pump relay without activating a zone via the controller, what ports on the controller would I need to jumper to the M/P port.

Assumption, the controller is plugged into an AC outlet.

On my old Nelson Smartzone EZ controller this was accomplished by jumpering a port named “HOTSPOT” TO THE M/P port.

Last, I use in this example a jumper but the jumper will actually be a switch.

Why do I need this, the well supplies water to the sprinkler system and to the pool. When pool guy needs to add water he turns diverter valve to pool and flips switch to start the fill. When complete, flips switch to close and turns diveter valve back to sprinlker system.

So back to question, M/V gets jumpered to which port?

Thank you.



I appreciate the answer…but in this situation can you elaborate the answer more. Are you saying jumper the -24VAC to M/P?

If you mean 24VAC- to the line going to the relay, which happens to connect to M, yes. I still would consider a SPDT switch. Would a picture help if you do not know about those?

SPDT comes in a regular light switch form, they are called a 3 way switch. Common would connect to the pump start relay, 24- to one brass terminal and MV to another.
You likely can use a regular switch (like you’ve used to), simply connect 24- via the switch to MV terminal, which in turn would have two wires (one to the switch, the other to pump relay).