The chirp comes at night, usually once a minute or so, and it is never clear which room it is in. Before that happens, someone in the house should know three things: which alarms exist, who tests them, and who gets the step stool when one starts to chirp. This guide is about making those answers exist before 2am.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
Walk the house and write down what is there
Start on the lowest floor and go up. Find every smoke alarm and every carbon monoxide alarm, including the ones in the basement, the hallway, the room she sleeps in, and any garage or utility area that connects to the house. For each one, note whether it runs on a battery you replace, is wired into the house, or is a sealed unit with the battery built in. Note whether it is a single-purpose alarm or a combined unit. Read the date printed on the back or side of each one. That tells you when it was made and, on most models, when it reaches the end of its service life. The manufacturer's label is the authority here, not memory.
Name who tests each one
Testing is the easiest part to forget and the hardest to restart once it has lapsed. Choose one person who owns the test and one person who covers when that person is away. Ask the owner to press the test button on each unit on the schedule the label gives, usually monthly, and to write the result on a sheet kept near the door or the kitchen. A test shows the horn works. It does not show that the unit is past its service life, so keep the replacement date on that same sheet.
Decide the chirp before it comes
A chirp usually means a low battery or an alarm reaching the end of its life. It is not an emergency, but it will not stop on its own, and in the middle of the night it feels like one. Settle these questions while the house is quiet. Who gets called first? Who has a replacement battery or unit on hand? Can the person in the room reach the alarm without a ladder? If the answer to the last one is no, the house has a placement problem, and that belongs in daylight, not at 2am. Do not pull the battery out to stop the noise and leave the alarm bare. Replace the battery, or replace the whole unit if it is sealed.
Keep the alarm and the person in the same plan
If she sleeps on a different floor from the nearest alarm, or if an alarm sits above a stairwell, write that down. A ladder is not a safe route for her, and a helper should not climb one in a dark hallway without someone holding it. Ask whoever is moving or installing things to place the alarm where it can be reached from the floor or from a stable step.
When it stops being a maintenance question
A chirp you can clear with a new battery is a house question. An alarm that sounds for carbon monoxide is not. Get everyone out, call emergency services from outside, and do not go back in until they say it is safe. If anyone in the house feels unwell, that belongs with a doctor or emergency care, not with the person who keeps the battery sheet. Once the house has been cleared, ask the fire department or a qualified technician to check the source before anyone sleeps there again.
What to check before you buy or replace
When you replace an alarm, compare the label on the new one with the old one. Check whether it is sealed or battery-replaceable, whether it is a combined smoke and carbon monoxide unit, and whether it links to other alarms so that one sounds for all of them. Ask whether the type you choose matches what is already wired in the house. Before you leave the store or the installer, ask to see the test button and hear the chirp, so the first one at night is not a surprise.
If the house needs hands for the climb, the wiring, or the test sheet, local help for keeping her home lists who can come. The order for reading the rest of this site is on the start here page.