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I have Honeywell with W, B, G, R, Will Nest Thermostat work?

BruceG
Community Member

I have Honeywell with W, B, G, R, Will Nest Thermostat work?

1 Recommended Answer

Jarhead
Community Member

The Honeywell original wiring should be:

S – Indoor and Outdoor Wired Sensors
Y – Compressor Stage 1 (Cooling)
Y2 – Compressor Stage 2 (Cooling)
G – Fan
C – Common
U – Humidifier, Dehumidifier, or Ventilator control
L/A – A – Input for heat pump fault
O/B – Reversing valve for Heat Pump systems
E – Emergency Heat
Aux / W2 – Heat Stage 2 (Heating)
W – Heat Stage 1 (Heating)
R – 24vac (Heating transformer)

So it is important to know where which cable was connected to the Honneywell.
By code, the colors are defined.
Unfortunately, this is not always the case and cables are simply clamped because someone did not know better.
In this respect it is important to know where white, blue, green and red were previously connected.

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6 REPLIES 6

Jarhead
Community Member

Do you have a picture of the original wiring for us?

BruceG
Community Member

Its white, blue, green and red. No other wires.

Jarhead
Community Member

The Honeywell original wiring should be:

S – Indoor and Outdoor Wired Sensors
Y – Compressor Stage 1 (Cooling)
Y2 – Compressor Stage 2 (Cooling)
G – Fan
C – Common
U – Humidifier, Dehumidifier, or Ventilator control
L/A – A – Input for heat pump fault
O/B – Reversing valve for Heat Pump systems
E – Emergency Heat
Aux / W2 – Heat Stage 2 (Heating)
W – Heat Stage 1 (Heating)
R – 24vac (Heating transformer)

So it is important to know where which cable was connected to the Honneywell.
By code, the colors are defined.
Unfortunately, this is not always the case and cables are simply clamped because someone did not know better.
In this respect it is important to know where white, blue, green and red were previously connected.

BruceG
Community Member

Correction … W, Y, G, R connected to Rc (bridge)

Jarhead
Community Member

You can ignore the bridge from R/Rh to Rc for the connection of a Nest thermostat.
There is no longer a bypass on the Nest.
Nest will take care of this circuit for you in the future.

If you really only have the W, Y, G and R wires on your old thermostat, it is up to you to decide which Nest to get.
See the compatibility checker here: KLICK

I would recommend the Nest thermostat E.
For your case even the normal Nest thermostat would be sufficient.
So it's up to your needs which one you choose.

MelbaDT
Community Specialist
Community Specialist

Hey folks, 

 

Appreciate your answer and recommendation, Jarhead. 

 

@BruceG, thanks for reaching out. I wanted to drop by and ensure everything is covered here. Let us know if you have more questions and we'll be glad to check on them. 

 

Best, 

Melba