Many smoke detectors are up high if in a vaulted ceiling that can't be reached by a regular garage ladder. That's why the $125. Lower detectors can be changed out just by standing on a stool or chair. Its usually the intermittent beeping that tells you the 9v battery needs replacement which is the problem in most cases.
” Its usually the intermittent beeping that tells you the 9v battery needs replacement which is the problem in most cases.”
I learned that the hard way many years ago, and that’s mostly the first issue that needs to be solved: buy a new battery