I am trying to connect the c wire but I'm at a crossroads of sorts. I have a dual zone so there are 2 thermostat wires come into what looks like a relay box ( see pictures) I have located the thermostat wires but I do t know where to connect the extra wire as there is nothing that indicates where the connection isenter image description hereenter image description here


Ecobee has a Power Extender Kit and a lot of documentation on what to do when you don't have a C wire. See: https://support.ecobee.com/hc/en-us/articles/360009155051-Installing-your-ecobee-thermostat-with-the-Power-Extender-Kit-no-C-wire-

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, props for taking our tour before posting; few newbies do. – Daniel Griscom Nov 19 '19 at 3:51
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    support.ecobee.com/hc/en-us/articles/… "Note: You will not be able to install the Power Extender Kit (PEK) with heat-only 2-wire systems. The PEK can only be used on furnace or heat pump systems that do not have a C wire — this is because the PEK requires R (power), G (fan), and Y (compressor) wires to operate, and these 2-wire heat-only systems do not have these G and Y wires." The Argo uses two-wire dry contact thermostats. – NoSparksPlease Nov 19 '19 at 3:58

In your installation documents from Ecobee find the diagram for Taco sr503-4, that is functionally equivalent to your Argo control board. The "t" wires to the left of the diagram connect to the T terminals on the Argo board. You will need parts equivalent to a remote power supply for the Ecobee (see amazon "c wire power supply"), and an isolation relay (like a White Rodgers 90-380).

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