Honeywell RTH7500D Owner's Manual page 21

Step 7. Connect Wires to New Wallplate (Cont)
NOTES FOR HEAT PUMP SYSTEMS
1 Leave metal jumper wire between RC and R in place.
2
If the old thermostat had separate wires on both the V and VR,
some system modification is required. Call your local heating
and cooling contractor for assistance.
3 If the old thermostat had wires on both O and B, be sure to
attach the B wire to the C letter designation on the new
thermostat. If another wire is already matched to the C, contact
Honeywell.
4 If the old thermostat had wires on W1, Y1 and W2, some
system modification is required. Call your local heating and
cooling contractor for assistance.
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