[kyleschat]

I have a BDP Thermostat 34427DP117 that I am trying to replace with a Honeywell RTH3100C. The BDP is wired thusly:
G - Green
Y - Yellow
E - Black
O - Orange
W1 - White
W2 - Blue
F - White
R - Red
T - Green (A resistor is jumped from T to C)
C - Brown (A resistor is jumped from T to C)

According to the Honeywell RTH3100C Installation Guide the proper conversion is:
BDP to HONEYWLL
G... G
Y... Y
E... E
O... O
W1... AUX (Should W1 & W2 be together?)
W2... AUX (Should W1 & W2 be together?)
F... L
R... R
T... Not Shown (What do I do with "T", and is the resistor jump still needed?)
C... C

[drtom4444]

First, do you have a heat pump or an electric heat/cool unit? It appears to be a heat pump from the way you have shown the wires to be, so far, but you have way too many wires. You will need to trace the wires from the inside and outside units to be correct. Start at the low voltage transformer inside the inside unit. One wire will be Common and the other will be "R." Common goes to one side of all relays and "R" is the wire supplying power to be switched in thermostat-the other side of the switches. "G" will go to fan relay, "W1 or 2" to heat strip relay or sequencers. That's all for inside unit. Then you have Common going outside along with "Y" and "O" and that's it. The wires are color coded to match the letters-R for red, G for green, etc. Make sure to turn off power to BOTH units before wiring. These are low voltage wires only which go to the coils of the relays. You have high voltage wiring as well which is being switched by the relays.