Honeywell t841a1779 to Ecobee3 heat wiring

I'm looking for a little help in regards to switching to a newer thermostat. I'm mostly having issues around how I should wire the heat. As far as my understanding, I have a heat pump with electric emergency heat.

The current stat uses X (assuming this is 'C'), W2, E, R, G, O, and Y.

My assumption for wiring this to the Ecobee3 would be:

Honeywell t841a1779 -> Ecobee3

• X -> C

• W2 -> W2 (aux)

• R - > RH

• G -> G

• O -> O/B

• Y -> Y1

But what would I do with the 'E'?

Reference Pictures: Album

Would appreciate any guidance!

submitted by /u/ThatOfficeMaxGuy
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