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Set up the Smart Thermostat: 24VAC Wire

Verizon’s Home Monitoring and Control (HMC) service allows you to monitor and control your home temperature via the Smart Thermostat. The Smart Thermostat needs a 24 Volt AC (24 VAC) Common Wire to supply power to it.  Follow the instructions below to determine if your home has the required 24 VAC Common Wire. We have also provided suggestions on how to proceed in case your home does not have the wire.

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Identify if your current system is using a 24VAC Common Wire

  • If you have a heat pump, your system already has a working 24 VAC Common Wire. Follow the steps in the Installation Guide (included in the box) to set up your Smart Thermostat.

  • If your existing thermostat has a terminal named C, COM, X, or B with a wire connected to it, your system already has a working 24 VAC Common Wire. Follow the steps in the Installation Guide (included in the box) to setup your Smart Thermostat.

  • If your current system does not meet the above criteria, go to the next section, which will help you identify if an existing wire can be used to power your Smart Thermostat.

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Locate the 24 VAC Common Wire


WARNING
Voltage hazard. Performing the following steps incorrectly can cause electric shock or equipment damage. Disconnect power to heating and cooling equipment before beginning installation.

This section will show you how to identify and locate the 24 VAC Common Wire required to power your Smart Thermostat. If you are unsure of performing the next steps yourself, contact a HVAC professional.

Steps: Instructions:
1.

Remove the cover of your current thermostat.

    2.

    Locate all unused (disconnected) wires from the thermostat wire bundle and write down the colors. Some unused wires may be tucked in the wall behind your thermostat. To determine if one of these unused wires is already a working 24 VAC Common Wire, you will need to check your HVAC unit by following the next steps.

     

    Note: If there are no unused wires available, contact a HVAC professional.

    3.

    Go to your HVAC unit and remove the cover(s) to access the 24 VAC furnace wire terminals. Find the 24 VAC common terminal identified with the letter C, X, B, or COM.

     

     24VAC Locate Graphic

    Locate the thermostat wire bundle inside the furnace panel. This wire bundle is routed from the thermostat, through the walls, and into the furnace panel. This bundle can be identified at the furnace by checking the wire colors connected and not connected and comparing to the wire bundle at the thermostat.

     

    24VAC Locate Graphic

     

    If there is a wire connected to the C, X, B, or COM terminal from the thermostat wire bundle, write down color of the wire. This is the 24 VAC wire to be used to power your Smart Thermostat. Follow the steps in the Installation Guide (included in the box) to setup your Smart Thermostat.

     

    Note: This terminal may already have a wire connected to it but it may not be a wire that goes to the thermostat. If this is the case, continue to the next section to connect a wire to the 24 VAC terminal

    24VAC Locate Graphic

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      Connect the 24 VAC Common Wire



      WARNING
      Voltage hazard. Performing the following steps incorrectly can cause electric shock or equipment damage. Disconnect power to heating and cooling equipment before beginning installation.

      This section will show you how to connect an unused wire in the thermostat bundle to the 24 VAC terminal at your HVAC unit. If you are unsure about connecting this wire yourself, please go to the next section.

      1. Find a wire from the thermostat bundle that is unused at the thermostat and at the furnace.

        24VAC Connect Graphic


      2. Connect the unused wire to the 24 VAC terminal, then replace the furnace cover. The 24 VAC Common Wire is typically (but not always) blue in color. If the blue wire is available, it is recommended that you use the blue wire.

      24VAC Connect Graphic


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        Compatible Systems

         

        Will your Smart Thermostat work with your heating or cooling system?

         

        Compatible with:Not Compatible with:
        The Smart Thermostat is compatible with single and multi-stage forced-air systems:

        • Gas furnace systems
        • Oil furnace systems
        • Electric furnace systems
        • Heat pump systems
        • Air conditioning systems
        Might be compatible with:
        • Boiler systems
        • Geothermal systems
        • Multi-zoned systems
        The Smart Thermostat is not compatible with:

        • Radiant floor systems
        • Heating systems
        • Dual fuel systems (gas furnace & heat pump combined) without adding a special kit.
        • Contact your preferred HVAC professional for more information regarding the special kit.

        24Vac Locate Graphic24VAC Locate Graphic24VAC Locate Graphic24VAC Locate Graphic24VAC Connect Graphic24VAC Connect Graphic
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