09/06/2026
**Hardwired smoke/CO alarms going off in the middle of the night — need advice**
This has been happening on and off since 2023. It always seems to happen at night; as far as we know, it hasn’t happened during the day.
Last night the alarms went off around 9:00 PM and again around 3:00 AM. We have alarms upstairs and downstairs, and I can never tell which one starts the alarm. This is probably the 10th or 11th time it has happened since they were hardwired and installed in 2023.
I’ve tested the batteries and they’re good.
An HVAC technician suggested it could possibly be related to moisture or condensation caused by temperature changes between day and night, but I’m not sure.
I’ve also seen people report similar issues even after replacing all of their alarms, so I’d rather understand the cause before replacing everything.
Has anyone dealt with intermittent nighttime alarms like this? What should I have checked, and could an electrician or alarm technician help identify which unit is triggering the system?
We have three small children, so getting this figured out would be a huge relief. Thanks in advance!