allows only the 
or 
to operate for temporary temperature overrides. It also limits the tempera- ture to the maximum heating and minimum cooling temperatures used in your program. This is especially useful in buildings where unsched- uled events are common. Anyone can change the temperature, but only between the temperatures you set and only for two hours or the number of hours you specify if you set up your Hold Till timing (see Temporary Program Override (page 34). To select or deselect this feature, refer to the CONFIGURA- TION section (page 25, steps 12 and 13).
Battery Back-Up.
Three “AA” alkaline batteries allow the thermostat to maintain its
program in the event of a power loss. They also operate the back light for viewing the display in low light conditions, and allow for armchair programming.
CHECK BATTERY will be displayed when the batteries are low. To assure optimum perfor- mance, change batteries once a year or when CHECK BATTERY is displayed. When changing batteries, always replace all three batteries with new “AA” alkaline batteries (for optimum performance, we recommend Energizer® batteries). If the batteries must be changed frequently, it may indicate a problem with the system. Contact the heating/cooling system manufac- turer or a service person. Remember that excessive use of the display
37
light will reduce battery life.
System and
Thermostat Diagnostics.
The display will indicate CHECK SYSTEM if the room temperature does not rise within two hours of the call for heat. After two hours the thermostat will quit calling for heat for one minute (this allows some furnaces to reset) and call for heat again. It will repeat this sequence three times. If the temperature still does not rise, it will continue to call for heat. This normally indicates the heating system is not working correctly. You may wish to consult your furnace manufacturer or service person.
The display will indicate CHECK STAT if one of the following occurs.
Features
