I am upgrading my thermostat from a Simple Comfort 2200 to a Hunter 44668. On the 2200 the wires being used are:

y1
G
E
w2
o
r
c

I've translated them out to the 44668 but can't account for 2 of the wires

y1 -- y1
g-- g
E -- unknown
w2 -- w/b
O -- yo
R -- SHOULD THIS BE RH OR RC?
C -- unknown

Can someone help with what E (Emergency Heating control in the 2200 manual) and the C (24vac Transformer Common Side in the 2200 manual)?

Thanks

The Hunter stat doesn't have auxiliary or emergency heat: Comfort Saver w/ Room Control Thermostat - 44668 by Hunter - Hunter - Hepatech and QuietFlo (http://www.hunterair.com/product/0-49694-44668-8.html)
Hence the W2 and E terminals are probably missing.

E- forces the heat pump to be off and the furnace only uses the electric heat strips to heat.
W2 - is the control for the heat strips. In a heat pump system, the heatpump is used most of the time. At a certain outdoort emperature (balance point), below where the heat pump and electric output are the same, the heat ump and strips are used at the same time.

Below yet another temperature, where the heat pump doesn't work at all around freezing, only the strips are used.

The Hunter tstat is the wrong one.

The common (C) terminal is sometimes optional. When the thermostat is entirely powered by batteries it is not used. It was not required for mercury thermostats.

Rc, Rh and R. Some stats use R, some R and Rc, and others use Rc and Rh. For a single transformer system, like you have (uses R alone, the termonals Rc/Rh or R amd Rc are jumped together.