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: T, T
The ecobee3 requires a C (Common) wire in order for the thermostat to receive constant 24VAC power. Typically a 3rd conductor wire is needed that can be used as the C-wire from the thermostat location to your furnace control. However there is a product called "Common-Maker" from Fast-Stat that will allow you to use your existing 2-wires without having to run a new C-wire.
See links for further information:
Fast-Stat website: http://www.fast-stat.net/
Wiring options: https://ecobee.zendesk.com/entries/96808048-ecobee3-Heat-only-2-wire-boiler-furnace-installations