The THA2 will work from a wide variety of power sources. It can operate from 12V to 24V AC or DC source. Battery backup will provide 35 hours of continued operation with a 9V alkaline battery. This battery should be changed after every power failure. During a power outage, the message Battery Backup! will flash every several seconds.
During a power failure, the unit will continue normal operation except during an alarm. When the alarm becomes active, the relay will close for only thirty seconds to conserve battery power.