Extra wire behind thermostat

[desi123]

Hi all I have an extra wire that’s red in colour coiled up behind my thermostat and I was wondering if I can use it as a C wire for my new smart thermostat. I’ve attached a picture of what my current thermostat setup looks like. Thanks for any help

 

[Megawatt]

Hi all I have an extra wire that’s red in colour coiled up behind my thermostat and I was wondering if I can use it as a C wire for my new smart thermostat. I’ve attached a picture of what my current thermostat setup looks like. Thanks for any helpView attachment 54131

First thing you need to do is find the other end of that wire to make sure it’s not hooked to anything