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: R, C, O, AUX,G, Y, S1, S2
Based on these connections your 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
C >> C
G >> G
Y >> Y1
AUX/W2 >> W1
O >> O/B
S1/S2 >> These are applicable with some heat-pumps and connect to an outdoor temperature sensor. This is not needed, the ecobee3 utilized internet weather to accomplish the same functions...cap this wire off.