4th Gen only heat / off

[Kylelundy]

My original thermostat has a Y/W wire, not both. It’s a single pipe fan coil unit where the heating and cooling is changed by the condo association seasonally. 

Is there any way to get this working so I don’t have to reset it and switch over from W to Y for heating to cooling? 

original wiring 

R - W/Y - Gl - Gm - Gh - C

[Derickf]

Hi @Kylelundy,

Thanks for reaching out to the community. I understand the situation you are having with your Nest Learning Thermostat 4th (Gen) and how annoying it would be to have to constantly change your thermostat wiring seasonally. Don't worry, help is here.

Even though your Nest Learning Thermostat 4th (Gen) can control your heating and cooling system, it can only control one terminal at the same time; each terminal W/W1 or Y/Y1 needs a wire properly connected to the right terminal to close the circuit when using the heating or cooling mode. Since you have one wire controlling both options, you will need to switch the wire to the proper terminal when turning on the heating or cooling due to the system you have being a nontypical installation where the heating or cooling is being controlled by the condo and not by the thermostat.

Don't hesitate to keep me posted if you have any other questions.

Best regards,

Derick.