Honeywell RTH2410B1001 Quick Installation Manual page 10

Quick Installation guide
Connect Wires (cont'd)
Heat Pump Systems with Auxiliary/Backup Heat
(Alternate Wiring)
If your old thermostat had E and Aux wires (or alternate
wires), connect both wires to AUX terminal.
Do not use L wire. Wrap bare end of wire with electrical tape.
Do not use C or X wire. Do not use B wire if you already have
O wire. Wrap bare end of wire with electrical tape.
This thermostat cannot be used if your old thermostat had
any two of the following wires: R, RC, V or VR.
8
8.