This house was built with the USI brand in 2006 . Most of them outlasted the 10 year advertised life . The were hard wired 9V battery backup .How do you like the Universal brand now that its been a while. They make a battery only smoke detector and HD has them.
The new ones I have are hardwired , ingergrated battery with 10 year battery life . No chirps no replacing batteries .
By mistake I ordered battery only . Still on board battery , but I wanted hard wired .
Anyway , Amazon refused a return because " I got what I ordered " so I'm stuck with 200 bucks worth of alarms . Went ahead and ordered what I needed , and put the batery ones on the shelf in storage .
What model number are the ones at HD that you looked at ?