Alternate Wiring - Honeywell RTH2510 Quick Installation Manual

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.