I ran the compatibility checker with a wiring configuration and the tool reported that ecobee needs to take a closer look. Can you please let me know if my system configuration is supported?
My thermostat has the following wires: RC, RH, G, WW1, O, YY1, B
Based on these connections the system is a 1-stage heat pump with 1-stage of auxiliary heat. This is a compatible system with ecobee3.
Due to a few slight differences in wiring terminals between your existing thermostat and the ecobee3 I will summarize the connections of your existing t-stat to >> ecobee3:
R >> RC
B >> C (ensure ok to use B wire as C wire by checking that the B wire terminates to Common terminal of furnace)
G >> G
Y >> Y1
W >> W1
O >> O/B (energize reversing valve on call for cool).