Trane thermostats are designed to provide optimal heating and cooling solutions that offer you control over the HVAC system. They allow you to control the temperature of your home both manually and automatically to your liking. The Trane thermostat is quite handy and can offer you many years of service.

X2 in a Trane thermostat is for emergency heat. Ideally, it delivers supplemental heat when in defrost cycle. The T wire on a Trane thermostat is for outdoor temperature compensation. Both X2 and T are not options for a carrier thermostat.

When installing your Trane thermostat, you need to know the functions of X2 and T wires and where they connect. Keep reading to learn more.

What is the x2 wire on a Trane thermostat?

The X2 wire on a Trane thermostat is meant to energize emergency or auxiliary heat during defrost cycle. This wire transmits the signal to the system calling for emergency heat when the outdoor temperature is too cold for the heat pump to work. Thus, it signals the secondary heat source situated in the air handler to operate.

What is the T wire on a Trane thermostat?

The T wire in a Trane thermostat is an outdoor temperature sensor. It allows your unit to sense the outdoor temperature remotely rather than at the unit. It transmits the outdoor temperature data to the heating and cooling control unit.

How do you wire a Trane thermostat?

Start by connecting the Trane thermostat wires. If you are replacing a Trane thermostat, make sure you mark the wires and then replace them. It is advisable to take a photo of the old wiring. However, if you are installing a thermostat from the start, you should pay attention to the color codes of the wires.

The power wire has a red color and it is connected to the R terminal of your transformer. The white wire is connected to the gas valve or relay for electric heat. The green-colored wire is connected to the G terminal of your Trane thermostat. Connect the yellow wire to the cooling contactor.

The orange wire is connected to the reversing valve. This is meant to energize it. The black wire is meant to bring on the emergency or auxiliary heat. This will come on automatically, depending on your settings.

After this, you need to test your unit by turning on the breaker. Make sure you test your system in both heating and cooling modes.

This video can help you understand how basic thermostat wiring is done:

How do you identify thermostat wires?

Thermostat wires are identified by their color codes. Remember that different thermostats can have different color codes.

Replacing a thermostat is quite easy. However, sometimes terminal letters on the old thermostat do not match up with the ones on the new thermostat. You need to know what each letter means. This will help you figure out where each wire should be connected to on a new thermostat.

These are the industry standard color codes for thermostat wires no matter where they are used:

  • W wire has a white color. It is connected to the heating system
  • Y wire has a yellow color and it is connected to the compressor of your HVAC system.
  • G wire has a green color and it is connected to the fan
  • C wire also known as the common wire has a blue color. It provides your smart thermostat with continual power.
  • Rh and Rc are red wires and are the primary power source for the thermostat. Although these wires are both red, you should not interchange them. They must be connected properly to the corresponding terminals.
  • O wire also known as the orange wire is connected to the heat pump. It is orange in color. Switches on your heat pump
  • The X2 wire is usually black. It signals emergency heat.
  • T wire is for the outdoor temperature compensation sensor

Wrapping Up

The thermostat is the controlling hub of an HVAC system. Every homeowner should know how to wire a thermostat. When it fails, you can repair or replace it yourself to save money and time. With modern Wi-Fi thermostats and programmable thermostats, replacing the old ones with new ones can be quite tricky. When installing your unit, you need to connect wires to their corresponding terminals. Make sure to check the manual of your thermostat for voltage requirements.


What happens if you wire a thermostat wrong?

If you wire a thermostat wrong, your system will not work or it might not work as intended. Also, you might damage your system.

Can you touch the thermostat wires?

No, you should not. Thermostat wires operate at low voltage, which has minimal risk of electric shock. This does not mean you touch them. Always shut off the main power to the thermostat when replacing or repairing it.


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