honeywell rth7460d1018 to nest

[Tailee89]

I connected my honeywell rth7460d1018 to nest gen 4

It doesn't power up.

from honeywell to Nest Red to RH,

Orange (Y to Y1)

Green to Green. 

White wire from OB to OB

Black wire from W2 Aux to W2

it does not power up. 

Any ideas?

Does it need a C wire. Should I simply run a wire from the C on the furnace to the C on the Nest as the Honeywell used 2 AA batteries. The nest is not powering up.

Also, could i try charging the Nest with the USB C port on the back and seeing if it powers up and asks for a C wire on the install?

Honeywell to Nest Gen 4 

[moralesvicente]

Hello Tailee89, 

Thanks for reaching out to the Google Community Forum. I understand you have some questions regarding the wiring configuration to install in a Nest Learning Thermostat 4th gen. Don’t worry; I would be more than happy to help. 

So based on the information that you’ve provided me, we need to connect the wiring configuration as follows:  

• Orange wire - Y1
• Green wire - G
• White wire - O/B
• Black wire - W2
• Red wire - RC 

Please note that color codes can vary. The key is to connect the correct wires to the corresponding terminals on the previous thermostat. 

Let me know how it goes. 

Regards,

Daniel 

[Tailee89]

Thank you for the reply. I connected it like that and the screen didn’t power up.  
i moved the nest to another unrelated thermostat and it does work fine. So there is a wiring issue. Maybe it needs a c wire?

[moralesvicente]

Hi  Tailee89, 
 
Thank you so much for keeping me updated. It's great to know you've taken action on the matter. To get a better understanding of the situation, please help me out by attaching a picture of the wiring connections on the back of your Nest Learning Thermostat 4th gen, because I’d like to know how you’re connecting the previous wiring system in the Nest device.  
This information will be useful to troubleshoot the situation more effectively.
 
Best regards,
Daniel

[Tailee89]

will attach a photo when i get home, but i connected Red To RH and got e448 no power.

should i try RH?

[Tailee89]

Attached is the wiring diagram.

There is a Bosch heat pump. An old furnace to distribute and a honeywell thermostat with AA batteries.

It says no power when hooked up to Nest Red to RC

wiring diagram

[Tailee89]

The blue wire on the furnace is C

[Tailee89]

[Tailee89]

it 

[moralesvicente]

Hey Tailee89, 

I appreciate your continuous communication and the effort you've put into installing this device. Regarding the error code displayed on the thermostat (E448), the device is not detecting power. This means that some wires aren’t sending voltage to keep your thermostat powered on, so I suggest contacting a Nest Pro to get professional assistance.

Best regards,

Daniel 

[Tailee89]

What if I added the Google Nest Power Connector - Nest Thermostat C Wire Adapter

 

[moralesvicente]

Hey Tailee89, 

 
Thank you so much for keeping me updated. I understand your concern. Due to this wiring configuration, you can connect a C wire or Nest power connector to supply it with enough power. However, we also need to have in consideration connecting all the cables properly in the accurate terminals to avoid future trouble, whence I can recommend you contact a technician to get further information. 
 
Best regards,
Daniel