Nest thermostat compatibility

While most 24 V heating and cooling systems are compatible with Nest thermostats, there are some systems that aren’t compatible. You can quickly tell if you have one of these systems without having to use the Compatibility Checker or to look at your thermostat’s wiring.

If you have one of the system types below, it won’t work with a Nest thermostat.

Proprietary systems If you find wires in your thermostat’s terminal that have non-standard labels (for instance 1,2,3, or A, B, C), your system is proprietary. If your system only has 2 wires, but you have both heating and cooling, your system is likely proprietary. Proprietary systems aren’t compatible with Google Nest thermostats. However, some proprietary systems provide an adapter you can use for it to be compatible with your Nest thermostat or you can have it rewired by a pro installer to be compatible.
Millivolt heaters Millivolt systems are typically wall heaters or floor heaters and use electricity or natural gas. These systems use much less electricity than low voltage systems and can't deliver the right amount of power to Nest thermostats.
High voltage systems  High voltage systems are usually electric baseboard heating systems or other radiant systems powered by electricity.  High voltage thermostats are often built into the wall and typically have 2 to 4 thick wires coming out of the thermostat. Wire nuts are often used to connect the thermostat to the system wires. High voltage thermostats are usually labeled 110, 115, 120 or 240 VAC. Note: In some cases, it is possible to make a high voltage system Nest-compatible. Contact a local professional and have them install a step down transformer to 20 - 30 V. High voltage thermostats should only be installed or uninstalled by a professional due to the high voltage that they carry.
Solid fuel systems Systems that use coal, wood chips, pellets, anthracite, or other biomass materials are typically incompatible with Nest thermostats.

Wired remote sensors

Remote sensor wires are typically used to give your thermostat outside weather data. These wires can’t be connected to Nest thermostats. But Nest thermostats don’t need wired sensors since they get weather information over Wi-Fi. Even if your system has sensor wires, it may be Nest-compatible.

Micro-controller based systems

Systems that use micro-controllers instead of relays are sometimes more sensitive to power sharing. If you have a micro-controller based system, your Nest thermostat may need a C wire or Nest Power Connector to be compatible with these systems.

Zone relay or control panels

Some systems have control panels or equipment interface modules that require a C wire to be compatible with Nest thermostat.

Incompatible system wiring

Too many stages of cooling or heating

• Conventional systems: Nest Learning Thermostat (4th gen) can support up to 2 stages of cooling and up to 3 stages of heating.  
• Heat pump systems: Nest Learning Thermostat (4th gen) can support 4 stages of heating, consisting of 2 stages heat pump heating and 2 stages of alternate heating. Nest Learning Thermostat (4th gen) can support up to 2 stages of cooling.
• The Nest Thermostat E is only compatible with one stage of heating, one stage of cooling, and an additional stage of either heating or cooling.

International systems

• Some international systems, such as Buderus boilers, have dry contacts or other incompatible wiring. These systems may require relay panels in order to be installed with standard American or Canadian thermostat wiring.

Heat pumps with L wires

• L wires are typically used to show system status, like emergency heat being on. Nest thermostats can work with systems that use Service Light (L) wires. While L wires can't be connected to the Nest thermostat, it doesn't need them. The Nest thermostat and Nest app shows you system status information without connecting L wires.

Forced hot water or steam systems

A dual fuel heating and cooling system (also called a hybrid or packaged system) is a combination of a heat pump for primary heating and cooling, and a furnace (usually gas or oil) that provides a second and/or third stage of heating.

Nest thermostats are compatible with these systems and support up to 2 alternate heat sources. 

You have a dual fuel system if you have a furnace inside your home, and a heat pump on the outside of your home. Heat pumps look similar to air conditioners, so check the label on your outdoor unit to make sure it’s a heat pump. If you’re still not sure which system you have, contact a local HVAC professional.

If you have a dual fuel system, you need to have a trained professional set up your thermostat. It’s important for a professional to assess the requirements for your specific dual fuel configuration since choosing incorrect options for a dual fuel system can result in damage to your system. Contact a local HVAC professional.