I have two TXU White / Rodgers thermostats. The downstairs unit loses about 1hour a day while the upstairs unit keeps perfect time. The units do not have backup batteries.
TXU rreplaced both units last week and the downstairs unit still loses about an hour a day. Both units maintain the proper programming when I reset the time.
What do I need to do to fix the downstairs unit?
If the power is supplied to both units rom the same source, why does one lose time?
What is the source of power for the thermostats?
I have two separrate air conditioners and one common gas heating unit in the attic.
Thank for any help you can provide
Ian

Thermostat power comes from a transformer mounted within the furnace or AC enclosures. With 2 AC units and 1 furnace, there could be more than one transformer. The offending thermostat may be bad or it is wired to a different source than the working unit.