Article Summary:
The Nest Learning Thermostat works with over 95% of 24V heating and cooling systems, including gas, electric, oil, solar, hot water, geothermal, forced air, heat pump and radiant. (Based on data collected through Nest’s online Compatibility Checker.)

The 2nd and 3rd generation Nest Learning Thermostats can control the following types of HVAC systems:

• Heating: one, two and three stages (W₁, W₂, W₃)
• Cooling: one and two stages (Y₁, Y₂)
• Heat pump: with auxiliary and emergency heat (O/B, AUX, E)
• Fan (G)
• Power (C, Rh, Rc)
• Humidifier or dehumidifier (HUM, DEHUM)
• The Nest Thermostat's connector can accept only one of these wires: W₃, E, HUM or DEHUM.

The Nest Learning Thermostat is designed to work even if your home doesn’t have a common “C” wire, but installing a new C wire may be required in rare cases.

Important Note: Professional installation is recommended for:

• Dual fuel systems (heat pump with furnace)
• Whole-home humidifiers and dehumidifiers

Not everyone knows what kind of heating and cooling system they have. Fortunately, there is an easy way to find out. All you need to do is remove the cover of your current thermostat and take a look at the wires that are connected.

There should be a label for each connector that has a wire. Write down each label or take a picture of your wires and use our Compatibility Check tool. There you’ll be prompted to enter the labels and we’ll tell you if your system will work with the Nest Thermostat.

If your thermostat has a short “jumper” wire between two connectors, don’t include that wire; only enter the labels for wires coming from inside your wall that are attached to the thermostat.