Confused my old system Wiring O and wired B

[tommycao108]

 

My old system have separated wire O and wire B, so how can I wire them to Nest Learning Thermostat? 

[Patrick_Caezza]

@tommycao108 

What is the manufacturer of the thermostat and HVAC?

I feel the Blue (B) wire is just a C wire.

[tommycao108]

 

[Patrick_Caezza]

@tommycao108 

Give this wiring a try

White - O to OB

White - W to W2 (set as AUX heat)

Green - G to G

Red - R to Rc

Blue - B to C

Red - Y to Y1

[tommycao108]

My old system have separated wire O and wire B, so how can I wire them to Nest Learning Thermostat? 

[Patrick_Caezza]

@tommycao108 

Post a picture of the current thermostat wiring.

[tommycao108]

 

[Patrick_Caezza]

@tommycao108 

I answered your question in your other thread

[Markjosephp]

Hi everyone,

I've duplicated your thread in the main one here. You’ll receive all updates on this issue on the main thread, and we recommend updating and checking this thread when needed.

Best,

Mark

[Markjosephp]

Hello folks,

I wanted to ensure that everything was covered here.

Thanks for looking into this, @Patrick_Caezza.

@tommycao108, a wiring guide was shared with you above. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

Best,

Mark

[tommycao108]

thanks for all of your help!  But still didn’t display any signs. Shall I charge the nest’s battery first?

[Markjosephp]

Hello tommycao108,

Uh oh! Could you share with us a picture of how you installed your Nest Thermostat? Also, please try charging the thermostat display for an hour and waiting until it turns on.

Keep me posted.

Regards,
Mark

[Markjosephp]

Hi tommycao108,

I'm checking back in — how's it going? Still need our help?

Regards,

Mark

[Markjosephp]

Hello tommycao108,

It has been a few days since your last reply, and we're going to lock the thread within 24 hours. If you have any questions, please feel free to create a new post.

Thanks,

Mark