Our alarm system was on the fritz. The smoke alarms were not working. The technician came out and announced that they were more than 10 years old therefore they had to be replaced. He also told us that he couldn't replace them unless we install smoke alarms on both floors of the house. WHAT??!! Why do we need additional smoke alarms if we have new alarms installed which are hooked up to the alarm system. ADT works in the strangest ways. The tech comes Wednesday. Anyway, we installed the alarms. Standby for updates.