EWC ST-3E to EWC NCM-300 Wiring?

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serpico1
Posts: 8
Joined: Thu Oct 17, 2019 6:33 pm

EWC ST-3E to EWC NCM-300 Wiring?

Post by serpico1 »

I have purchased a NCM-300 board to replace my old ST-3E board so that I can use the Nest thermostats throughout my house.
I sounded like it would be a basic swap out, but the wiring of my old board and thermostats is confusing me. I have down DIY electrical wiring in the past, so I am comfortable doing it myself, if possible. Otherwise, I would have to search around for a HVAC tech or electrician familiar with EWC systems.

I have attached a photo of my 3e board and how it is currently wired.
I have 3 thermostats in the house. zone 2 and zone 3 have the same wires into the thermostats, red, white, yellow and green wires.
My zone 1 thermostat has 6 wires (refer to photo) Im not sure why the 6 wires, but when I looked up my Nest gen 3 thermostat compatibility, I stated the wiring was not compatible with the Nest.

Can I wire this myself? or should I just have a pro come in?
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Thanks in advance for any help completing this wiring issue
Tom
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Steven W.
Posts: 58
Joined: Tue Jun 25, 2019 9:13 am

Re: EWC ST-3E to EWC NCM-300 Wiring?

Post by Steven W. »

Give us a call today and one of our techs will walk you threw it.

1-800-446-3110
Steven R. Weisneck
Technical Engineer
Tel: (732) 446-3110 Ext. #461
www.ewccontrols.com
sweisneck@ewccontrols.com
serpico1
Posts: 8
Joined: Thu Oct 17, 2019 6:33 pm

Re: EWC ST-3E to EWC NCM-300 Wiring?

Post by serpico1 »

Ok, thanks
I will reach out tomorrow when I am home
Closedguard10
Posts: 3
Joined: Mon Jan 24, 2022 12:34 pm

Re: EWC ST-3E to EWC NCM-300 Wiring?

Post by Closedguard10 »

I am looking to do the same, what did you end up doing with the B/O?
serpico1
Posts: 8
Joined: Thu Oct 17, 2019 6:33 pm

Re: EWC ST-3E to EWC NCM-300 Wiring?

Post by serpico1 »

I havent swapped out the panels yet. its been pretty cold here, so I was waiting for a more milder day before starting the swap.
But, from one of the bulletins I received from EWC for swapping out the ST to the NCM300, the O & B wires are not needed. I know the Nest state requires a common wire, so either the O or B wire can be repurposed for the common "C" wire
Closedguard10
Posts: 3
Joined: Mon Jan 24, 2022 12:34 pm

Re: EWC ST-3E to EWC NCM-300 Wiring?

Post by Closedguard10 »

Thank you for the reply. We actually already have common wires to the thermostat. So I'm assuming in this situation we could completely illuminate the O and B?
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