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Nest Thermostat with 3 zones

Community Member


I have an oil fired furnace with 3 heating zones using the Taco zone valves. I had one Nest E thermostat without a C wire that is installed with good voltage. I tried to installed 2 more and started getting power error codes (voltage under 2.8). I purchased 2 power adapters (sounds like I'll need 1 more) however I'm not sure how to wire these up. I have two control boards it looks like. A Honeywell and a Taco control board. At first I assumed the Taco control board went to the taco zone controllers, but I think after tracing the wires, it only controls my hot water, is that possible? I read that I may need  24v adapter thing as well? Or is that likely already installed somewhere? I'm ready to just hire a pro for this, but just trying to get some thoughts first.


PXL_20221211_213731311 (2).jpgPXL_20221213_225641803.jpgboard1.PNG


Community Specialist
Community Specialist

Hi mmpmpaaa,

Thanks for posting and for the photo.

Your current heat pump system has a complex setup. With that said, I suggest reaching out to a pro technician to properly wire your system and make sure that you utilize the most out of your system


Hey there mmpmpaaa,

Checking back in should you still have some questions here. Let us know by replying to this thread. 


Community Specialist
Community Specialist

Hi everyone,

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.


I appreciate the help, Mel.