I'd like to replace my thermostat with a new one. My current thermostat is one that doesn't have a C-wire and is powered by batteries.

Now, my question is... is there a switch for the power that I need turn off too? I could not find a switch for the thermostat in the breaker box.

I'm assuming just removing the batteries is fine for replacing my thermostat?

  • There is usually a 24V transformer in the furnace that powers the thermostat. You should turn the furnace off or you risk shorting the leads and anything from blowing a fuse in your furnace to dammage a control board. – Ed Beal Feb 9 '16 at 0:21
  • I have a Carrier FX4CNF. I searched all over the manual online to see if there is a switch but I am not seeing one... – user3822494 Mar 23 '16 at 18:27
  • The 120v breaker that powers the furnace should kill it if there is not a local switch. – Ed Beal Mar 23 '16 at 18:43
  • If your return is in ceiling, the switch is in attic. – Shane 0 Sep 11 '20 at 23:26

Simply turning off the breaker that feeds the furnace will turn off the thermostat power as well.

  • 3
    Depending on the installation, there might be a switch near the furnace (serviceman switch). This can also be used to turn power off to the furnace. – Tester101 Feb 9 '16 at 11:47

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