We left on Sunday to get daughter to college. I leave the forced hot air gas "back up" at 57 when I'm gone. Was in the singles and teens with wind here Sunday through Tuesday night when we returned. Walked in house felt really cold. Checked indoor thermometer 38, checked thermostat, fell off in my hand! I replaced batteries a few months earlier and must not have refastened correctly!! Uh oh. Replaced. But immediately loaded the IR! Burned it hot for three hours and then reloaded for the night. Lots of covers on the bed. This am it was 58 in house. Reloaded and now it is 65 and climbing. 20 degrees wind and snow outside. Very thankful for no frozen pipes, just as thankful for this IR! 2000 sq' colonial. Coming up to temp.