redditmpm t1_j9y3uqc wrote on February 25, 2023 at 12:10 PM Reply to Old 2-wire thermostat wiring by fluxeii You will need to run a third wire (a constant). It’s pretty common when upgrading to a fancier thermostat. There should be a spot on your furnace to attach it. If pulling a new wire is doable, it’s a pretty easy job. Permalink 0
redditmpm t1_j9y3uqc wrote
Reply to Old 2-wire thermostat wiring by fluxeii
You will need to run a third wire (a constant). It’s pretty common when upgrading to a fancier thermostat. There should be a spot on your furnace to attach it. If pulling a new wire is doable, it’s a pretty easy job.