Last check for EWC-ST-3E conversion to NWM300

[stephenmurcko1954]

Layman switching from EWC-ST-3E to NWM300 so I can use Ecobee thermostats. Single stage heating (gas) and cooling. 3 Zones.
Have read the swapping instructions and dabbled in the Tech Bulletin.

1. In the picture of the transformer and system blocks, would I take these as-is? The red/white wire in upper left goes into a humidifier.
System wire across bottom. Or do I have to swap 1/2 at the transformer block?

2. I can hook up the "C" wire on the control board "Thermostat 1" for the "C" wire on Ecobee?

3. When I swap out the controller board, I assume I must swap out the antique thermostat on zone 1?

4. I assume I can temporarily leave the 3 wire thermostats on zones 2 and 3.

Any feedback is appreciated.

Thanks,
Steve

PXL_20231203_211841352.NIGHT.jpg

[Steven W.]

If you are looking for a Thermostat for the master zone on your ST-2E / ST-3E zone boards here is a list of Thermostats that have the separate "O" and "B" connections that you are going to need for the master zone. Remember the ST series boards are master/slave (Winter/Summer manual changeover) so you are going to need these two connections on your zone 1 thermostat for your board to work correctly.

FYI
When you are programming the EWT-601-2 and EWT-725 Thermostats for the ST-2/3E Boards program them to Heat/Cool not Heat Pump. The Heat Pump setting will not work for the ST-2/3E Boards. There are NO WIFI thermostat's that will work with the ST boards.


EWC Thermostats
EWT-601-2 – None Programmable
EWT-725 - Programmable



PRO 1 Thermostats
T601-2 – None Programmable
T725 - Programmable

[glepage01]

Steven, what is wrong with the attached drawing of possible wiring of a wi-fi thermostat (for main/zone 1) with a ST-3E board?

https://ewccontrols.com/forum/download/ ... iew&id=248