Slightly off the wall question, but is there a way to tell if the thermostat is operating on wall power vs. battery? I installed 2 thermostats last year, including the C-Wire, and at about 16 months, both are triggering battery warnings now. According to the manual, they should last about a year on battery, or “much longer” on wall power since battery is only used during power failure. This has me wondering if I somehow wired the power wrong and I’m running on battery alone.
Yup, I’m on battery. The interesting thing is the house had programmable thermostats when I bought it, so I’ve got power there somehow, but can’t quite tell which. Only 4 wires, and no yellow common wire, but the old thermostats had fan control, so I don’t think it was the “cheat” method of wiring them either. I guess for now, I’ll leave well enough alone, can’t complain about 15 months of battery life. If I get some spare time, I’ll trace the wires to find out.