I've just ordered an ecobee 3 lite thermostat for my one-pipe steam system.
The boiler is a few years old and is a Williamson-- https://www.williamson-thermoflo.com/products/williamson/gsa-gas-steam-atmospheric
At my thermostat location I only have 2 wires. No C-wire.
So, my options appear to be:
1) Power the thermostat with an external plug-in 24V transformer, which I can hook into the closet on the other side of the wall from the thermostat so there would be no visible wire. This seems rather easy and I've ordered the transformer already. From my understanding this is fine because I do not have cooling system.
2) Run a new set of wires to the boiler. I just wouldn't know where to hook them on the boiler. Here is picture of the transformer area and the wiring diagram for the boiler. Currently, the white thermostat wire hooks to Y on the transformer and the red wire hooks to G. C on the transformer seems to hook to the 24V ground on the burners, etc. Would I just hook the new wire to C? I think it would have to be soldered on or maybe could find somewhere to splice it.
Any benefits to doing the extra work for option 2 above or is the plug-in transformer option just as good?
Lastly, are there any settings I should concern myself with when using the ecobee for steam radiator heat?
Thanks for any help!