Wiring a thermostat

[emcgee]

I'm having trouble installing my thermostat.  The instructions tell me that it's incompatible, but I think that it is.  The wires that I have are R, i+, i-, and C.   Can someone help me?  Thanks.

[CoolingWizard]

@emcgee , your thermostat is a digital thermostat provided by the manufacturer to uniquely control their HVAC equipment. The R and the C wires provide power for the thermostat, and the I+ and I-  are communications lines.  The thermostat uses a communications based on RS485 standard.  That system is not compatible with a conventional HVAC con system. Now, hope is not lost. me the manufacture model number of the unit that you have, I can look it up and see if it also includes a secondary control system based on 24 V AC..

The AC Cooling Wizard

[emcgee]

Thanks for the quick reply.  I have a Lennox EL296UHV

[emcgee]

The A/C is a Lennox XC17

[CoolingWizard]

@emcgee that is one heck of a high-efficiency gas furnace. The good news is it does have traditional or more conventional connections in the furnace. The bad news is that you may not have enough wires in your thermostat cable to do this. You have a two stage gas heating system that takes two wires ( W1 and W2). The R and the C take the other two wires. You still need a wire for Y1 and for G. Your Outdoor air conditioning unit is also be high-efficiency and may have a need for a second stage wire (Y2) in the Nest. You might want to check your thermostat cable that’s behind the current thermostat and see if there’s extra conductors cause you’ll need a total of seven conductors.

AC Cooling Wizard

[emcgee]

Thanks for the advice.  It sounds like this is a little above my pay grade.   My old thermostat has gone blank, which was the reason for the replacement.  I guess that I'll need to call for service.  I will keep your advice for the installers in case they can use the nest thermostat.  Thanks again!

[CoolingWizard]

@emcgee , this what the iComfort Communicating control board in your Lennox furnace looks like.
 
if you have wires connected in the red box area above, that means your outdoor unit is also an iComfort, communicating unit. Your current thermostat is connected to the terminals in the yellow box above. Can you go outside and get me the model number of the Lennox unit?

AC Cooling Wizard 

[emcgee]

XC17 - 036 -230 -08

S/N 5815G04478

[Jake]

Hey there,

I wanted to check in with you, and let you know that I will be locking the thread in 24 hours.

Best regards,

Jake

[CoolingWizard]

That unit also has a very intelligent control board so it’s possible they’re using the  iComfort control on the outdoor unit as well.  That would mean that would probably have to rewire that unit. In addition to the thermostat cable might have to be upgraded on both ends.

AC Cooling Wizard

[zoeuvre]

Hi emcgee,

I’m sorry to hear about your Nest Learning Thermostat situation. I see that your control panel has the non-standard labels of i+, i-, and C, which are incompatible with our Nest Thermostats and mean that your system is proprietary.

Proprietary systems aren’t compatible with Google Nest Thermostats. However, some proprietary systems can be rewired by a pro installer to be compatible.

Let us know if that helps.

Thanks for your help, @CoolingWizard. 

Best, 

Zoe. 

[zoeuvre]

Hi there,
 

I wanted to check and see if you managed to see the information I shared. Please let me know if you have any questions from here. I would be happy to assist and make sure you are good to go.
 

Thanks, 

Zoe