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Discussion Starter · #1 ·
Hi everyone
I was wondering if I could get some help with this wiring diagram

I am trying to wire up the nest thermostat from this existing one.
I know the I have both electric heating and cooling, but not sure which wire is which since the both on top and bottom of each wire there is labeling. If someone could please help thought would be grrrrrreeaaat!!!
 

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Looks like you have a heat pump.
Just to throw this out there, I'm not a fan of the Nest, especially with a heat pump. If your going to use a programmable thermostat with a conventional heat pump it's important to select a thermostat that will control the electric heat based on outdoor temperature. Does your nest have this function? Otherwise continually adjusting temperature in heating mode will use the electric heat to recover the space temperature, which will increase your utility bill.
Air source heat pumps are happiest when they maintain temperature.
 

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Discussion Starter · #5 ·
Looks like you have a heat pump.
Just to throw this out there, I'm not a fan of the Nest, especially with a heat pump. If your going to use a programmable thermostat with a conventional heat pump it's important to select a thermostat that will control the electric heat based on outdoor temperature. Does your nest have this function? Otherwise continually adjusting temperature in heating mode will use the electric heat to recover the space temperature, which will increase your utility bill.
Air source heat pumps are happiest when they maintain temperature.
So does that mean I go by the bottom labels?
Also I got it as a gift
I am not sure if it has that function
 

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So does that mean I go by the bottom labels?
Also I got it as a gift
I am not sure if it has that function
Yes the bottom.
You'll have to read the literature to determine if it has outside air auxiliary heat lockout.
Also make sure the common wire actually is hooked up at the air handler. Otherwise the Nest will try and power steal using the other wires which can cause problems. Had one customer hook up a Nest with a broken common and woke up to the house at almost 90* and the heat was running consistently.
White is aux heat.
 

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Discussion Starter · #8 ·
Yes the bottom.
You'll have to read the literature to determine if it has outside air auxiliary heat lockout.
Also make sure the common wire actually is hooked up at the air handler. Otherwise the Nest will try and power steal using the other wires which can cause problems. Had one customer hook up a Nest with a broken common and woke up to the house at almost 90* and the heat was running consistently.
White is aux heat.
So i need to check the outside unit for the common wire you said, that will typically be what color(Black Im assuming?) or will it be labeled common or COM or something like that?
 
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