EWC-ST-3E and Nest?

[gfunkdave]

Hi all,

I understand that the ST-3E is not generally compatible with Nest. I'm wondering if it's possible to connect the Nest to existing wiring from the ST-3E, with the Nest working as the main thermostat. I'm OK with losing some functionality in doing so, but I don't want to buy a new zone panel or run new wires.

Are there any options, or is there no way to use Nest with the ST-3E?

Thanks!

[Paul Z.]

You need the "O" & "B" to operate board. You do not have that with that thermostat. The NCM-300 will work just fine.