I need to upgrade my control from [b]EWC-ST-2E[/b] to [b]NCM-300 [/b]but not have a few things I'm not sure about before I embark on the switch. I've attached 2 images: [list=1] [*]Current wiring setup for the EWC-ST-2E panel [*]Proposed wiring for the new NCM-300 panel [/list] However, I have the following questions: [list=1] [*]Where should the 'R' and 'W' wires for the HVAC go to? 'R' to 'RH' or 'RC'? 'W' to 'W2/E' or 'W1/B'? [*]If I'm planning on installing two Ecobee 4 Thermostats (one for each of the 2 zones) how should they be configured? Should a wire be repurposed for 'C' to provide power? And what about 'O/B'? I assume I now only need one wire for this? [*]Is there anything else to consider. [/list] Thanks

I have an Applied Comfort scwc15k00q7a42 PTAC in my apartment. The unit has 1/2 (low/high) heating and 1/2 cooling settings, where the PTAC itself supplies AC, and in the cold parts of the year, heat is driven by blowing air thru a hot water radiator that is regulated by a zone valve connected to the PTAC. My primary issue today is that the PTAC's built in thermostat isn't working properly -- it works, but doesn't cool lower than ~mid-70s. Almost seems like a calibration issue, as if I hold the "sensor," it starts cooling again from the warmth of my hand. Any general suggestions around what could be causing that? Separately, if I'm going to try to fix this, it occurred to me that it might be nice to try to wire in a smart thermostat ala Ecobee or Nest. Is this even an option? Wiring diagram and what I can see in the AC are 3 wires coming in/out of the thermostat... red, white, black. Here's the link to the AC & parts list: [url=http://www.ptacs.com/serviceparts/model/SCWC15K00Q7A42/]SCWC15K00Q7A42 Service Parts | Applied Comfort Products[/url] Here's their PDF of the wiring diagram: [url]http://www.ptacs.com/static/products/wiring/802599.pdf[/url] Any help or advice would be appreciated. Let me know if I missed any crucial info. Thank you!