Upgrade from ST-2D to NCM-300

[zombyw00f]

I want to upgrade my old control panel (EWC ST-2D) to a modern unit (EWC NCM300) with modern thermostats (Honeywell RTH9580WF). The 24V, Zone2, and Zone1 motor wiring seems straightforward, but the system wiring does not seem as easy. I currently have only a Y, W, G, and R wire connected to the control panel, and I am not sure how to correctly wire this to my new panel. Can you please confirm how to properly wire this panel to my system?

[Paul Z.]

your system wiring is the same, the difference is NCM has a W1/B, W2/E. You will be using only RC/RH (which is linked together) Y, W, G. You might not have enough wires in zone 2/3. You will not be using the "G" (which will not give you independent fan).