Parallel controllers, stuck zones

I just hooked up a new 12-zone Rachio, but I hooked it up in parallel with my existing non-Rachio controller just until I developed faith in how the Rachio worked. I ran a test run through all the zones with the Rachio and it seemed fine. This morning the old controller tried to run on zones 1 and 6, and I can’t really tell what it did. However, those two zones are now stuck on via the Rachio. I found them both on. I’ve disconnected and reconnected the power to the Rachio, and as soon as it has power the two zones turn on again. I can completely disconnect the two zones from the old controller and they stay on, so I know it is in the Rachio.

Did something the old controller do cause the Rachio to lose its mind?

Did I miss something that said it was a no-no to have an old controller still hooked up?

Well, seems like there are not any ideas about what caused this or what to do about it.

I bought it from Costco, so I’ll take it back. Seem Rachio has some things to iron out, or else some warnings to document.

I am not sure I am understanding. Are you saying you have the wires from zone 1’s valve connected to Common and ‘1’ on both controllers? That seems like a dangerous thing to do, feeling the power for a zone from one controller to another, etc.

Well, no it was not dangerous. It doesn’t feed (or feel) power. All the controller does is connect the zone 1 wire to the common wire to turn on zone 1. Nothing more. Two controllers should not interfere with each other, as far as I can tell. I’m a retired electrical engineer, but I may have forgotten something.

Doesn’t matter. I took it back.

Ooops, feed is what I meant (sorry for the typographical error). I am not a EE so I can be wrong. I am not understanding what some of what you wrote such as “the zone 1 wire to the common wire to turn on zone 1”. To me, running in parallel would mean zone 1’s common would go to the common terminals on both controllers and the same thing for the “hot” wire going to both zone 1 terminals. This would mean to me that if one controller was powering zone 1, 24VAC would be going to the other controller (unless you put diodes to prevent current from doing this). I probably am not understanding something, sorry.