Buzzing Solenoids

I just got and installed a 12-zone Rachio 3. Using 3 zones + master valve. The solenoids are buzzing something terrible - except for one of them. I have tried 9 different solenoids in different configurations - even directly connected to the controller (so as to remove the cable variable) - and they all buzz - except one. Doesn’t matter where I plug the one in - zone 1, 2, 3, master - this one solenoid is silent as I expect and silent. The solenoids are all Orbit. So I am unable to figure out what is going on - is it the controller? But if it is - why does the one solenoid silent? Or are all the Orbit solenoids at fault? I checked the voltage out of the Rachio 3 - it’s 24.6VAC.

Sounds like your old solenoids are from a DC / battery-based controller, whereas Rachio is an AC controller.
Do they have different colored wires (red and black)?
Alas, you won’t be able to use them directly with the Rachio, or any other modern, controller; that being said you should be able to buy / replace the solenoids themselves, without changing out the valve bodies (and dealing with plumbing).
Include some photos of buzzing & silent solenoids, so we can tell for sure. Also if you have a photo of your old setup, it may prove useful.
The silent solenoid has likely already failed and has ceased, if otherwise it looks like the rest. Running others for prolonged period would result in a similar failure.

All the solenoids are brand new 24V.
And the silent solenoid is working 100%

24V AC or DC?


I assume all AC - as there is no mention of +ve or -ve on the cabling - both black wires.

Well, I too would guess them to be AC. The voltage seems like it should be within tolerances (yours is at 2.5%). I saw on the first link that you provided a comment about “Odd sound” and described a humming. I did not look further and do not use Orbit, so cannot tell you if that is common or not. I am not saying it is for sure the valves, just trying to help you figure that out.

For the life of me, cannot think of any good reason which would explain the selective buzzing while being directly connected to the controller. Can you share photos of your test setup, with valve(s) directly connected? Is your meter capable of measuring AC current? If so, what kind an amp reading do you see?
Did you buy the valves at the same time? If so, it’s possible that they are part of the same batch and have the same issue(s). I’d try buying at least two more and checking if they are silent.

I bought 6 more valves today at a different store (could be same batch indeed). There are no batch numbers on them - except same product codes. They all do the same thing. I’d say it’s definitely the new controller - except for the one valve that clicks, works perfectly and doesn’t buzz. I’ve disassembled the setup for now - so no pics.

@ColinRachio - I found this link with a quick Google search →

maybe it will have some hints/tips/tricks that will help.

If you have access to a multimeter (volt/ohm) what is the resistance through the coil in the solenoid that doesn’t buzz, versus the ones that do buzz?

I tested the silent and one of the buzzers and they are both 62 ohms.

Measure the voltage at the good and bad solenoid(s) when energized.