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Pretty common problem here but the posts I've seen are a little different. New Wi-Fi tstat, no C terminal at furnace but plenty of available wiring at both ends. Unlike others problems posted of unwiring and rewiring, couldn't I just take an available wire and combine it to my G connection at the terminal and then connect wire at tstat? If G controls the fan and I know there is power because I can turn on fan manually, is this the easiest fix?