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Thermostat WiringHVAC system for 2 stage geo-thermal

Community Member

I am replacing a Robert-Shaw thermostat on a two stage geo-thermal heat pump  which provides both heat and air conditioning . There is no emergency heat backup on the system . Hopefully I can use a Google Nest but currently I have 7 wires connected as follows: Most Nest diagrams show 4 or 6

C - blue

R - Red

Y1 - Yellow

W2 - White

Y2 - Brown

G - Green

O - Orange

There is nothing connected to E/W1 or B.

Do I just transfer wires to corresponding terminals regardless of color ?

Much obliged in advance


Silver Product Expert
Silver Product Expert

Try this

Red to Rc

Orange to O/B

Since you do not have aux heat put White to W1

Match up the rest

If it is not working in correct mode you might have to go into the settings for OB wire it has A or B output mode so if you get Air Cond when you wanted Heat switch the OB setting.

Houptee -- NJ Master HVAC Licensed Contractor

Community Specialist
Community Specialist

Hello there,


Thanks for confirming the wiring configuration, @Houptee.

@Noreaster, I wanted to stop by and see how I could help. How's it going? Have you tried installing your new Nest Thermostat? Also, here's a quick reference on how to install a Nest Thermostat. Please let us know if you have any other questions or concerns.




Hi Noreaster,


I wanted to see if you still needed help. Please let us know if you have any other questions or concerns.



Hello Noreaster,


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