I am replacing my old thermostat. The old is a TEMPSTAR, the new is a Honeywell model # RTH7500. when I use the directions I end up with one left over wire. We called the Honeywell hotline, the rep. said to wire it like this: red to R, white to O, Yellow to Y, Blue to C, Green to G, Orange to O/B. The problem lies with the white wire to O. There is no O, just O/B. So the white wire is left over. where do I put this wire. Terminals I have left are: Aux, E, L, and RC. Also, RC and R have a jumper installed.

White to O page 10

Please make your selections on page 19,20,21.

READ the manual. if it is to difficult for you call a professional. Damage can be caused by wrong hook up.