2 Red from 2 separate system Mirror Nest

[ronaldjj80]

I have a Nest (the mirror) thermostat. I have separate heating (Rh, W) and air (G, Rc, Y, C).

There's only 1 R on the nest thermostat. How should i proceed? Someone said that I can tie both R coming from the separate systems together and then pigtail it into the thermostat.

Is this a viable solution? thanks

[Markjosephp]

Hello ronaldjj80,

Thank you for reaching out and letting us know about your inquiry. I'd love to help.

Some HVAC systems, called dual transformer systems, use separate power sources for heating and cooling (Rc and Rh). If you have both an RH and an RC wire, you have a dual transformer system, which would work for Nest Learning Thermostats. Check out this guide for Nest Thermostat compatibility and let us know if you have more questions in mind.

Best regards,

Mark

[ronaldjj80]

Thanks for the heads up. I was able to get everything connected. But now the rh "power" is grayed out on the wire configuration. This is strange because when I direct connect the W and Rh wires my heat comes on without issue.

[Markjosephp]

Hey there,

Thanks for letting me know. Let's sort this out.

A few questions: do you see any wiring reports or message codes? Could you send us a picture of your thermostat's wiring setup? Also, please check the power status under the technical information settings.

I'll look forward to your response.

BEst regards,

Mark

[Markjosephp]

Hi ronaldjj80,

I'm checking in to make sure that you've seen my response. Please let us know if you have any other questions or concerns.

Thanks,

Mark

[ronaldjj80]

Hi Mark

Yes thanks for the response. I was able to get the nest learning stat. I have another challenge. I also have the 1 system stat(mirror version) on a 2 wire heat system. There is no C connection so I purchased the 24v power supply but with only 1 R terminal ok the backplate how should I connect the power supply? One goes to the C terminal on the backplate bit how would the other wire go?

[Markjosephp]

Hi there,

Thanks for getting back to us. Let's see what we can do.

Installing it by inserting the power wires into the R terminal might help, but it's not an ideal way for configuration as it might damage the internal breakers of the base. I'd suggest that it would be better to install a Nest Power Connector.

Here are some references to help you install your Nest Power Connector on your HVAC system.

• Installing the Nest Power Connector
• How to install the Nest Power Connector (video link)

Feel free to let us know if you have more questions.

Thanks,

Mark

[Markjosephp]

Hello ronaldjj80,

I wanted to see if you still needed help. Please let us know if you have any other questions or concerns.

Best regards,

Mark

[Markjosephp]

Hi ronaldjj80,

I'm just checking in to make sure that you've seen my response. Please let us know if you have any additional questions or concerns before I close this thread in 24 hours.

Thanks,

Mark