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Thermostat C wire to "COM" on Taco SR502?
I'm replacing a thermostat in one of our zones with one that can use the "C" wire for power. All I have is heating (hot water, 2 zones). The old thermostat there are 3 wires in the wall behind the existing thermostat, but only 2 were in use. One connected to "W" and one connected to "Rh" (which was also jumpered to "Rc" (See picture below). I tracked the wiring down to the Taco SR502 switch relay and found that "W" goes to the left side "T" in zone 1, and "Rh" goes to the right side "T" in zone 1 on the Taco (see Taco wiring picture below). The third wire was not connected at the switch relay either (colored red with black tape on the end in the Taco picture).
For the new Stat. can someone please confirm that W and Rh wiring would be the same and the only additional step to supply constant power to the thermostat is to use the third wire to connect "C" on the stat to "COM" (upper left hand corner of the Taco picture) on the switch relay?
Your help is much appreciated.