Wiring noob here. Can someone give me step-by-step instructions for where and how I should attach a C (common) wire to a Triangle Tube Prestige Excellence 110 boiler for a ecobee3 thermostat? I think the gray box on top (pictured below) with the blue, brown, red and white wires is the 24VAC transformer, but I'm not sure, and I'm not sure where or how I should connect a C wire. Thanks!
I think the 24v terminal is the orange one on the bottom right labeled with the ports 7 to 19. you should be able to confirm this by seeing only small (18 or 20 gauge) wires entering into these ports and a red and white wire in location 7 and 8. I am installing a Nest thermostat and if I need a Common wire, I will add some comments when I figure this out too! I sent triangle tube a request for this information. Scott