C wire and smart thermostat
I don't know if you ever got this worked out or not, but I'm in the same boat.  Bought an Ecobee3 and I have the RA832A relay.  It doesn't appear as though it has any sort of C wire capability.  

Awhile back before I bought the unit or knew what my boiler was using in any sort of detail I reached out to Ecobee and this is what they said (I was planning to merge the boiler and AC into one thermostat as they are two separate now).  

They said:


  The boiler would use Rh and W. The AC would use Rc C G and Y


On their support site they have an article talking about what you can do if you don't have a C wire and one of the options was use a transformer and isolation relay.