Honeywell RTH9590 User Manual page 21

Installing your thermostat
Alternate wiring key (Heat Pump System)
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Do not use K terminal. For future use.
2
Leave jumper loop in place.
If your old thermostat had both V and VR wires, check wifithermostat.com for help.
3
If your old thermostat had separate O and B wires, attach the B wire to the C
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terminal. If another wire is attached to the C terminal, check wifithermostat.com
for help. Attach the O wire to the O/B terminal. On the Type of Changeover Valve
screen, select Cooling Changeover Valve. See page 69. If your old thermostat
had an O wire and not a B wire, attach the O wire to the O/B terminal.
If your old thermostat had separate Y1, W1, and W2 wires, check
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wifithermostat.com for help.
If the old thermostat has separate wires on Aux and E, use a wire nut to attach
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both wires to a separate wire. Slide this third wire into the W2-Aux/E terminal.
This is the system monitor. If the monitor finds a problem, you will see an orange
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alert button on the thermostat home screen.
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