Honeywell T8090A Owner's Manual - Page 8

Inserting Clock Batteries Power is supplied to the clock by the 24 Vac transformer, by two AAA alkaline batteries (included), or by the heating or cooling control circuit. Backup batteries may be installed to supply power to the clock if power is interrupted when using 24 Vac powering method. Install batteries in thermostat as shown in Fig. 2. Once a year or when batteries are dead, replace with two new AAA alkaline batteries. We recommend Energizer® batteries. BATTERY LOCATION FOR (2) AAA BATTERIES; INSTALL WITH POSITIVE ENDS UP M7188 Fig. 2-Inserting clock batteries. 69-0574-2 8