Nest 4th Generation learning thermostat compatibility with Lennox VRF system 4 wire

[jstraw]

I have  a new Lennox VRF Heat pump/Heat Recovery HVAC system and I want to add my Nest  4th Generation learning thermostat.     My wire coming from the wall has 4 wires (black, white, red, green).   I tried using the black wire in the yellow nest position but its not working.    Does anyone know how to wire this correctly?

[Patrick_Caezza]

@jstraw 

Post a picture of your current thermostat's wiring here.

[jstraw]

Here are the wires to my  Lennox VRP  system.  How do I hook them up to my Nest 4th  Gen learning thermometer?

[Patrick_Caezza]

@AxelD 

Your system is incompatible with any Nest thermostats as it uses a proprietary 12v interface.

[AxelD]

Hi @jstraw,

Thanks for posting in the Community! For sure, I can definitely help you with this wiring configuration assistance. Thanks for the photo provided. No worries, help is here! Please provide me with the following information:

1. Have you tried connecting the black wire in the O/B spot?
2. Is your system for heating only?

Keep me posted.

@Patrick_Caezza, thanks for your help!

Regards,
Axel. 
 

[jstraw]

hello Axel,  it is for both heating and air conditioning, but it is a heat pump system

it is the Lennox VRF 

[AxelD]

Hi jstraw,

Thanks for confirming your system's modes! After reviewing the photo of your wiring, I noticed it contains thread wires. These are incompatible with Nest Thermostats, which require hard wires.

Therefore, your system may not be compatible with the Nest Learning Thermostat 4th Gen. This is likely why it's not turning on your system.

Regards,

Axel.