I have an American Standard heat pump AC. I'm replacing a White-Rodgers manual thermostat (where I move a switch from cold to heat) with a Honeywell RTH7600 (which will automatically switch from cold to heat).

When I take off the old thermostat, I have a red wire (power) that will go to the Rc with a built in jumper. I have a green wire (fan) that will go to the G. I have an O wire that will go to the O/B.

My problems lies with the yellow wire. My yellow goes to the Y and also to a W. If I'm reading my manual correctly, I think I can put the yellow wire only to the Y since the new Programable thermostat automatically switches from cold to heat.

Is my thinking correct?

2 Answers 2


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See below, if you jumper Yellow to White the heat strips will run in both cool and heat as Yellow is energized in both modes, what makes it a cooler or heater is the O being energized in cool mode Rheems use the B terminals to be energized in heat.


Iblieve you need to wire up as heat pump manufacturer istructions show.The 24vwires are electronic signal wires,keep cable separate from mains cable to avoid upsetting the signals,mixing them up can be a costly error.familiarise yourself with instructions,before connecting system and try to understand how these connections differ.This is understandable,high tech and old tech combined,be patient,you may need time to get it.Steve uk egineer.

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