Replacing Honeywell T8112D1005 (1) HVAC & furnace

[MannyG]

I purchased a Nest Thermostat with Y/C/W/G/R/OB. The Honeywell has W/Y/G/R/Rc. Can I use the OB slot on Nest for the Rc on the Honeywell?

[CoolingWizard]

@MannyG ,  the typical older style Thermostat had both Rh and Rc with a jumper wire between them. When there was a separate heating system like a water boiler, you would connect the boiler to Rh and your air conditioner to Rc.  So, in your case you can ignore the jumper.  Your wire that is attached to the RC/RH on your old thermostat goes to the R on the Nest. 

AC Cooling Wizard

[MannyG]

Thanks for the response, however, I do not have a jumper cable on the Honeywell. I have all the slots on the Honeywell taken by the corresponding wires. I do have a separate baseboard heating system and central air which like you mentioned are on Rh and the other on Rc. Should I tie the wires together and insert them into the OB slot on Nest? 

[CoolingWizard]

@MannyG , no Manny, what you’re gonna need is a nest learning thermostat you cannot use the basic nest thermostat. You must have a thermostat that has an Rh and an RC. And then you’ll hook it up the heating system to the Rh and you hook up the cooling system to the RC.

AC Cooling Wizard