Master Valve Hookup Using 2 Controllers

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Thanks in advance for all suggestions. I have 2 separate irrigation systems watering 5 acres. Originally 1 system irrigated from the well and the 2nd system around the house was on city water because of the rust from the well staining the house and cars. I started pumping the well water into the pond and pumped out of the pond for irrigation to eliminate the rust and connected both systems. For the 2nd summer the well has gone dry in the hot months. I now have to use city water for both systems until October when the well produces again. I have a master valve on the original city water system. To be able to use both controllers I used isolators to connect the controllers together. The 2 cables that connect the controllers together are connected to the p/mv terminals and the common terminals on each controller. I tried attaching the original mv wire back on the same terminal but it doesn't open the valve. I have a separate transformer connected to the valve to keep it open, but it is a lot of trouble to turn it off and on when needed. The system is old and leaks often so I need to keep the water off the system when not needed. Is there a dependable timer I can install on the mv to open with the controllers or another way to wire it in the controller?


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Orlando, Florida
First you need to have a backflow preventer between the two systems so the pond water doesn't contaminate your domestic water. It can be deadly.

"I used isolators to connect the controllers together."
What are isolators? Do you mean wire nuts?

The common wires (usually white) of both systems need to be tied together If they are on the same circuit.

Trying to understand the set up. You want either controller to open the Master Valve. Are both controllers on the same 120v circuit? This is very important the both are on the same phase from the electric panel. Not necessarily the same breaker. If not you can burn out the 24 v transformers.

You can get a cheap 4 zone controller (Orbit brand) and set the on time for when you auto start the other controllers. The MV terminal has power when any zone is running. You can wire the MV to Zone One and set the start times, up to four a day usually.
Hey, wait a minute.

This is awkward, but...

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