I'm trying to follow the ecobee instructions here:

Which uses a wiring diagram as such:
(source: ecobee.com)

I have this relay:

And here is the wiring diagram for the relay:

Can someone tell me how the ecobee diagram translates to the relay diagram? Which numbered terminals are going to T & T and which one is going to W1 and Transformer N? Thanks.

Edit: Additional info about my specific setup. This is the overview of my furnace:
I have the main zone which is where I want to connect the smart thermostat. I have a 2nd zone which I'm leaving alone. I have a 3rd for the water tank which I'm also leaving alone.
This is the wiring for the main zone. The T&T are in the upper right and although you can't see it there is a 3rd green wire that is currently not in use but available.
main zone (aquastat) diagram:
zone 2 diagram:
zone 2 wiring:
water heater wiring:

  • Can you post photos of the wiring at your thermostat and your boiler? Nov 27, 2018 at 12:47
  • I updated with additional photos. I didn't take the thermostat apart yet. It's an old mercury honeywell.
    – John
    Nov 27, 2018 at 13:00

1 Answer 1


You actually happen to have the relay oriented in your photo the same way the relay in the diagram is oriented.

  • W1 to terminal 1
  • C to terminal 3
  • Boiler T&T wires to 2 and 4

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