EWC-ST-3E to NCM-300

[deejaybos]

Recently moved into a new home with a 3 zoned central air system. As a new/young homeowner, I would like to be able to future-proof our home and get some of the latest money-saving tech installed. I've read plenty of posts that our old multi-zone board will not allow for today's standard thermostats (ie. Nest, Ecobee, latest wifi Honeywell, etc.) As an amateur, I will be able to follow the wiring diagram to swap out the two panels, everything seems very black and white. Where my confusion sets in is the thermostat wiring itself.

Based on the picture of the panel, it looks like zone 1 is a "master" zone with all the wiring required, where as zone 2/3 are slaves. Looking at the pictures of the thermostats, you can see that whoever hooked them up used all wires, for all 'zones'. I'm not sure how to identify the master zone, even though I assume it's the main floor. I can't attach the 3rd zone thermostat that's in the basement, but it also includes all the wire hook-ups, but according to the panel, 2/3 should only have W/Y/R wired to the thermostat. Once the panels are swapped, I assume it will be W/Y/R/C. If I hook up 3 nests, will I still be in a master/slave setup or will the 3 thermostats be able to function independently (ex. zone 1 is heating and zone 2 is cooling.)

I'm definitely not HVAC trained, but I can follow instructions, I just don't want to pay $100s to have someone follow a wiring diagram for me and hook up a few thermostats for me.

*Edit* After looking over the panel wiring diagram again, I see that on the NCM-300, every zone looks like a "zone 1" from the ST-3E, so I understand that there is no longer a master/slave setup and that all zones are independent. So if that's the case, I can just wire them all identically, but also include the C-wire that is required by all newer thermostats. Will I be able to use my current/older thermostats in the meantime with the new wiriing requirements, ie. not using the O/B wires anymore? If it helps, the two thermostats I'm working with are Honeywell RTHL2310B

[Steven W.]

Yes the NCM-300 will work for you and you can replace it yourself. You can use the old thermostat's until you want to replace them with new ones.
I attached the wiring diagram to help you with swapping out your old ST board to the new NCM-300. If you have any other questions please give me a call.

Steven R. Weisneck
Technical Engineer
Tel: (732) 446-3110 Ext. #461
Fax: (732) 446-5362 or (732) 446-4946
www.ewccontrols.com
sweisneck@ewccontrols.com

[deejaybos]

Steve,

thanks for the reply. I actually had ordered the NCM-300 and ended up returning for the BMPlus 3000 with the idea that maybe in a few years we'll replace our single stage furnace/AC with multi-stage stuff. Once wired up using the older thermostats, I assume I can/will need to continue to use the switch on the thermostat that changes from heating/cooling mode. Is this correct? Since there is no master/slave thermostat on the newer zone boards, does that mean I could have Zone 1 on heating and Zone 2 on cooling?

[Steven W.]

You will not need that Heat / Cool switch anymore. Yes you can have Zone 1 set to heat and Zone 2 set to cool. Just a reminder you can not run heat and cool at the same time.

[deejaybos]

Somewhat of a bonus question, since the house was already wired up before I moved in obviously. Is there an easy way to identify which thermostat represents zone 1, 2, and 3? If I need to troubleshoot a thermostat or damper, I need to know which is which when the time comes.