Nest thermostat compatibility

[Dc1111]

Hello. I am trying to determine whether my thermostat wiring is compatible with the Nest thermostat. The existing wires are labeled a C, R, I+, and I-  

 The existing thermostat uses 24v AC power. It controls a natural gas furnace (Lennox SLP98UHV) and Carrier AC (24AHA4). 

[CoolingWizard]

@Dc1111 , what are the labels under the wires your photo is not clear enough because the yellow wire looks like “i+”

AC Cooling Wizard

[Dc1111]

C, I+, I-, and R

i did some more research on Lennox thermostats. They seem to use their own wiring arrangement in an attempt to lock customers in to their overpriced thermostats. 

[CoolingWizard]

@Dc1111 , in an effort to bring more advanced functionality, the manufactures created proprietary digital communications between the thermostat, indoor unit and outdoor unit.  There are temperature sensors in the outdoor unit and indoor unit that allows the proprietary softener to maximize the system operational efficiency.

Most of these systems have a conventional control interface as well.  If your thermostat cable has 5 or 7 wires in it, you can convert the control system from digital to conventional and then you can use a Nest Thermostat. 

AC Cooling Wizard

[Jenelyn_O]

Hi there,

Thanks for posting in the Google Nest Community forum. I just want to check if you managed to see the response above. Please visit this support article for additional reference about Nest Compatibility. 

I appreciate your help, @CoolingWizard.

Best,

Jenelyn

[Jenelyn_O]

Hi Dc1111,

I wanted to follow up if you still need help. Please let me know if you’re still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks,

Jenelyn

[Jenelyn_O]

Hey Dc1111,

Just one final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know. 

Regards,

Jenelyn