How do I install batteries in the Pro Th4210D?
Install batteries in the back of the thermostat. The thermostat uses two AA alkaline batteries and can be powered by batteries alone or, if used with AC power, can provide backup power to save time/day settings and power the display during power interruptions. (Page 6)
Have a follow-up question?
AI-powered answers from the official manual. Verify critical info.
Common questions