topic 3 Nest Thermostats for 3 Zones on Taco SR-503 in Nest Thermostats

3 Nest Thermostats for 3 Zones on Taco SR-503

chip_vd — Sat, 26 Nov 2022 18:33:51 GMT

I'm about to install 3 nest thermos on a three zone system and I want to be sure I am doing this correctly. Each location has three wires, but only two were being used by the old termos (W and R). I'm not sure the third is hooked up to anything on the basement side, but I am seeing one extra wire coiled around each of the thermo wires in the basement at the Taco SR-503 relay box (top right of image - green and yellow coiled wires). Should I be hooking these extra wires up to the COM port (top left)? If so, should all three loose wires go to the same COM port?

As a plan B, I do have three Nest Power Connectors. In my scenario, is it easier to simply use those? Thanks for your help.

Re: 3 Nest Thermostats for 3 Zones on Taco SR-503

Jhonleanmel — Wed, 30 Nov 2022 21:49:54 GMT

Hi chip_vd,

Thanks for posting and sharing a photo of your wiring. You have an advanced system that requires a technician to determine where these wires are connected to from your control board and which system it affects.

I suggest reaching out to a local pro to discuss your options.

Best,

Mel

Re: 3 Nest Thermostats for 3 Zones on Taco SR-503

Jhonleanmel — Mon, 05 Dec 2022 17:58:38 GMT

Hey chip_vd,

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

Best,
Mel

Re: 3 Nest Thermostats for 3 Zones on Taco SR-503

Jhonleanmel — Tue, 06 Dec 2022 17:59:29 GMT

Hi chip_vd,

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.

Thanks,
Mel