This will drive you nuts. 2 wire system. Have spare wire with thermostat to use for C. Hooked up c to common on transformer. Measure between R & C at thermostat I have 26V. Hook up nest get lower power??
Same problem -- Nest installed in a new house, WITH a C wire tested to have 27V AC on it, but Nest says error N260 (problem with C wire). Had been working fine for months, now suddenly not enough power?
Not sure what the deal is. Good luck getting any support from nest. I have a feeling I will be, Returning all 3 nest thermostat and doorbell if I can't figure this out.
