EWC-ST-2E to NCM-300 for NEST

[jtsi2001]

I have read several topics on this forum since the purchase of a NEST thermostat and realizing my current control board is not going to work. I like others am no HVAC expert but comfortable with DIY wiring. Looking at the manual to make the swap it all looks good with the exception of a few areas where my wiring is different. I have attached pictures of the overall wiring of my system and when zoomed in you will see that the Yellow and Brown wires are together on the main boards system "Y". also the zone motors on my system are using the M1,M2,M4 vs M1,M2,M6 in the diagram, my zone wiring is abit different as well but I'm assuming this may be to the master/slave setup. lastly there is a white and blue wire which I'm not certain where the originate from tied together

I will be purchasing the new board soon and hoping I can get some assistance with the wiring

[Steven W.]

Good morning;

My name is Steve i am one of the Tech's here at EWC Controls.

When you get a chance can you give me a call.

Thank You

Steven R. Weisneck
Technical Engineer
Tel: (732) 446-3110 Ext. #461
Fax: (732) 446-5362 or (732) 446-4946
www.ewccontrols.com
sweisneck@ewccontrols.com

[rlinane]

I purchased a nest learning thermostat that I wanted to hook up to the EWC-ST-2E

I ran into an issue and had to call Google for installation assistance.
They were telling me that I had a O (brown) and a B (blue) wire and they said that it was unusual.
He said that you usually have either or but not both.

The furnace is an american standard gas hot air furnace with an ac unit.
I don't think it is a heat pump thou as it is close off for the winter and shut it off at the breakers.

I have attached a picture of the old thermostat wiring and the ewc-st-2e board with current wiring.
there.

If you could give me advice on how to install this to the nest that would be great!

thank you,

Rich Linane
rlinane@gmail.com

[Steven W.]

If you are swapping out the ST-2E for the NCM-300 then you will not need the O or B terminals they are now spare wires.