Sorry maybe should’ve added a bit more detail for context but this isn’t a new install. The entire heating setup is from the late 80s. I just bought the house and wanted to update the thermostat to a programmable one in hopes to cut down on unnecessary heating when no one’s home. But 90% of the stats out there now are 24v. I did find one 120v stat but it said right on it not for hot water baseboard. But I will definitely look into the transformer/converter, thanks for your help!

I dm’d you a picture of the wiring. Can’t figure out how to add it to the post 🙄

Is that something I can put in myself? Or do I need to call in a professional. And would it get wired at the thermostat end or on the furnace end and have to run new wires the whole length of the run?