Two old sprinkler controllers with one rachio


I have two old sprinkler controls(A and B).
A has 8 wires connected but only 4 zones are activated.
B has 12 wires connected but only 8 zones are activated.

I am wondering if I can buy a 16-zones Rachio to replace A and B?

Thanks for your advice and suggestions.


Are all the wires hooked up or only the ones that are active? In other words, how many valves are there? If 12, that should be no problem. Pictures might help.

1 Like

Hi Thomas,

Thanks for your reply!
A’s wires are not hooked while B’s wires are hooked.

Hi Allen

In theory your two controllers are driving 8+4=12 valves.
There are two considerations that might be conflicting with a replacement of these controllers with a single new controller.

  1. Valves may be driven by two types of operating voltage. Either AC or DC.
    To make sure both controllers use the same operating voltage you can check the power supply on both controllers. It should read 24 V AC (usually) or 24V DC (rarely).
    Better yet, use a voltmeter and verify by probing between ‘Common’ and any one of the controller terminals ‘1’…‘12’.

  2. Create a map of your sprinklers and verify that every controller output is connected to one (and only one) sprinkler. You want to make sure that the current installation has no built-in ‘trick-circuits’ to create some logic like run sprinkler 3 when both controllers are active on it.

If the above points are verified you are free to replace with any controller that can drive your valves (AC or DC).

Cheers, Sebastian

At least the second controller is 24 VAC, I am not positive about the first and forgot to ask about that. If it is also 24 VAC, then that is good.

I am confused by the following two statements that seem to conflict with each other. I presume the ‘A’ and ‘B’ correspond to the labels on the pictures?

I see:

  • four wires connected (2 not connected) on ‘A’
  • 12 wires connected on ‘B’

If some of the wires are hooked up, but not going to a valve, I probably would not connect when just in case they touched the common wire somehow and the zone was accidentally turned on.

The question that @wpd84 posed about any “trick circuits” might be important. Please do make a map of each ZONE (not necessarily each sprinkler although that might help you in the future). We want to make sure one valve exists on each wire with nothing tricky done. It seems unlikely, but want to make sure. That is why I asked, how many valves do you have?