Hey folks. So I have a 3-zone taco controller, along with 3 nest thermostats. Home has no C wire, only heat (R + W). I used 3 nest power connectors as well, and a 24V transformer as the TACO controller couldn't push enough power.
I updated the software on all 3 thermostats and installed as per above. I validated each nest sees the power connector (self test was successful) and returned a result similar to this:
We are seeing an odd behavior when one thermostat calls for heat, all 3 now call for heat (we can see all three zones lit up on the Taco, as well as the other thermostats in the app are now "red").
I'm not sure this is a wiring issue but wanted to double check if anyone sees anything glaring. A boiler service tech stated something about potential diodes being needed, but this is puzzling because the only shared nodes are the L "hot" 24V wire and the three R inputs to the thermostats. I would think that the thermostat still controls whether it calls for heat or not.
tl;dr: I'm not sure how a mis wiring here could cause a non-intended thermostat to call for heat. Any ideas?
