Have Model EWC-ST-3D to NCM300 retrofit

[Ifsrob888]

What a great forum for your products. I currently have EWC-ST-3D and purchased the NCM300 after careful investigation and reading on this site. I will changing the thermostats to Nest so according to findings the NCM300 was the best fit. Hope I am right. I wanted to do the swap but I noticed that there is a transformer that connects to the C wire from the furnace to the transformer and the second wire connects to Y. THERE are actually 2 wires in the system Y screw down connector (one from furnace and one from transformer). Do I just not use the transformer and take C line and connect it directly to the System C screw down connector? On the zone 1 T-stat I should abandon the O and B connection and use one of those wire in the C spot on the zone 1 t-stat to use it as the C on the Nest thermostat...correct?

I have a Goodman forced air gas furnace and Goodman outdoor AC unit.

Thanking you in advance for your assistance.

Rob

[Paul Z.]

Give a call and I will go over the NCM-300, and your wiring.

[Ifsrob888]

Update:

The transformer I discussed earlier was for the outside condenser unit. Wired it accordingly and have full functionality of the board and Heat as well as AC. I also installed the Nest thermostat and the SAS sensor and it is all working perfectly. Thank you so much.

[Bigman]

Thanks Patrick...

I also need to make some adjustments to get rid of a whistling sound when only my loft system is activated.
I have a bypass damper installed that returns excess air to my return duct.
rubber flooring sheet

[Paul Z.]

Give a call to office, a few things to talk about. 1800 446 3110 X490

[avtex]

Hi Paul, same issue but to prepare, what do i need to know before calling you? mg

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[avtex]

NEST T-Stat working!