I am not aware of a Gen4. As an HVAC contractor, I tend to sell Nest E Learning thermostats and Gen 3 Nest Learning Thermostats. Sometimes consumers aren’t looking for the advanced learning features, and I will steer them towards the Nest Thermostat. As long as you go with a Nest Learning thermostat or a Nest E Learning thermostat, you can use the Nest app or the Google home app. If you go with the basic Nest thermostat, it only works with the Google Home app. Other than that any model you get that meets the needs of your system will be fine. If you have multiple heating stages or multiple coolings stages, you will need a learning type thermostat.
To see which works with your system, use the Google Nest Compatibility checker. you will need to look at your current thermostat wires and input which terminal letters wires are attached to. The compatibility checker will then make a determination as to which thermostat options are going to be available to you. I hope this helps you, make sure to add Kudo. If my answer solves your question, be sure to mark it as Recommended Answer.
The AC Cooling Wizard
NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
