ST-2D upgrade to NCM300, now Zone 2 not working

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leeg23
Posts: 1
Joined: Sun Mar 31, 2019 12:21 pm

ST-2D upgrade to NCM300, now Zone 2 not working

Post by leeg23 » Sun Mar 31, 2019 12:31 pm

I recently swapped out my ST-2D for an NCM 300 in order to upgrade to an Ecobee4 Smart thermostat. My set up is:
Oil-fired boiler with air handler and AC compressor outside. 2 zones, with Zone 1 controlling heat/cool/fan, and zone two a slave "temperature selection only" thermostat.

I followed the wiring diagram for ST-2D-->NCM300, but now when zone two slave thermostat goes below ambient temp, the compressor turns on, even if zone 1 is set to heat. As per the EWC wiring diagram, I moved the W Y R wires from zone two to the new board - Zone 2 thermostat has only 3 wires.

Zone 1 has W Y R G C (five wires) to the ecobee currently.

Is this a problem with my zone 2 thermostat, being that its a slave thermostat? Do I need a heat/cool selector thermostat for zone 2? Are there recommended thermostats that work with NCM 300? Zone 2 can be a very basic thermostat. Do i need to run more wires to zone 2 thermostat?

Any help is greatly appreciated...my family is not thrilled....

L

Paul Z.
Posts: 212
Joined: Thu Dec 08, 2011 3:05 pm

Re: ST-2D upgrade to NCM300, now Zone 2 not working

Post by Paul Z. » Mon Apr 01, 2019 7:53 am

Give a call 18004463110X490 a few questions

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