This system has two stages of Heat. Stage one is W and stage two is W2. It has a single stage of cooling ( Y), a blower fan (G) and the input , Power IN (R). Using the nest installation app, input the wires in use, W2, W, Y, G, R. Set system heat type to Forced Air. Without additional information about your HVAC system, I cannot go much further to help you. Just follow the installation steps as outlined in the documentation provided with the Nest thermostat and the online configuration tool. Nest software and configuration tools are pretty smart and as long as you tell it what wires are being plugged into which terminals and what color wire they are so you know where to put them on the new one, it will understand that you have two stages of heat and it will tell you where the W2 wire of the old thermostat gets plugged into on the nest backplate. Depending on your system type in fuel type it could be placed in * or it could be placed in AUX. The configuration tool will know where to put it and most importantly it will tell the thermostat itself where to find the second stage of heat. Cannot simply look at the wires on the old thermostat and plug them on the best back plane and get it all to work you must follow the installation steps including installing the nest app and following the online configuration tool that you’ll be directed to.
Ken, The Cooling Wizard
NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
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