I am replacing an old Honeywell thermostat heat only. The wires are not labeled and no label on the terminal. What would the brass terminal wire color be and what color would
![hvac - Can I use this unused blue wire as my C wire for my new Nest thermostat? - Home Improvement Stack Exchange hvac - Can I use this unused blue wire as my C wire for my new Nest thermostat? - Home Improvement Stack Exchange](https://i.stack.imgur.com/IpvcC.jpg)
hvac - Can I use this unused blue wire as my C wire for my new Nest thermostat? - Home Improvement Stack Exchange
![Can anyone help with figuring out wiring for the Thermostat? O/B vs O and B separate - Home - Wyze Forum Can anyone help with figuring out wiring for the Thermostat? O/B vs O and B separate - Home - Wyze Forum](https://global.discourse-cdn.com/wyze/original/3X/0/2/0216c8cdde30ac968349206e3900b9935dd2429a.jpeg)
Can anyone help with figuring out wiring for the Thermostat? O/B vs O and B separate - Home - Wyze Forum
![iO HVAC Controls UT-SWM Universal Thermostat Smart Wire Module with 2 to 5 Wire Adapter - Amazon.com iO HVAC Controls UT-SWM Universal Thermostat Smart Wire Module with 2 to 5 Wire Adapter - Amazon.com](https://m.media-amazon.com/images/I/51gVG+4Zt9L.jpg)