Replacing t8411r with rth230b
Hello,
I purchased a Honeywell rth230b to replace my Honeywell t8411r. When I removed the t8411r I had 6 wires coming out of my wall that were attached to the thermostat. A red, blue, green, white, and 2 yellows. The 2nd yellow is coming from a second set of wires that all have the same color, but the rest are pushed back and were not used. I cannot figure out how to wire this thing up with this extra yellow. I have no idea what it is for. It was attached to the "O" screw on the old thermostat plate. I can't even find out what that "O" was used for on the old thermostat.
Can anyone help?