I have been considering a smart thermostat since the Nest came out, I shied away because I have 20 yr old HVAC wiring with no C-wire, just 3 wires. I read about nightmares installing the Nest and frozen pipes when the Nest failed, so I gave up. I am happy with my other Wyze products, so I’m thinking about trying the thermostat, but I can’t find the answers to two important questions. 1) is the no C-wire thing a problem for installation and function? and 2) Is there a back up if the higher functions fail, i.e., will my furnace still kick on in the dead of winter? I searched the website for this info and couldn’t find anything.
3 wires should be enough using the C adapter, but post pix of your wiring at both the tstat & furnace.