We have a mysterious beeping/chirping sound that occurs in the house. It starts in the morning usually. Five beeps in a row at a regular interval, then five beats again after about a minute or so. Repeats constantly for a couple of hours, then stops completely. Then a couple of weeks later, it starts again. We installed new smoke/CO alarms recently that work with an app and has voice commands, so it's not that. We don't have a landline, so it can't be a phone connection. There are no children here, so no electronic toys. It seems to be loudest in a bathroom near the vent. What could it possibly be?

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    Could be a prank, e.g. amazon.com/… . If it's near a vent, what sort? If it's heating duct, it might be a signal to change the HVAC air filter. Feb 3, 2022 at 21:18
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    I hear stuff like that all the time which my wife is able to magically ignore. I cannot sleep until I've resolved the noise. The ticking of a clock is enough to keep me up at night. Get someone with a keener sense of hearing to track down the noise; a house doesn't have too many places for a consistent noise to hide.
    – MonkeyZeus
    Feb 3, 2022 at 21:25
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    We change the HVAC filter on a regular basis. The vent is above the furnace one floor up. Called a friend electrician. He says there may be another old smoke detector in the ceiling above the furnace somewhere. It may be hard-wired and losing its battery backup power. That's why it comes on again after a couple of weeks. Can't find the thing though. Looked everywhere. Its the only explanation that makes sense. Sheesh! Feb 3, 2022 at 21:35
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    Have a look at: diy.stackexchange.com/a/10904/18078
    – Ecnerwal
    Feb 3, 2022 at 21:53
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    Do you have a UPS, mine beep when the batteries are going bad. We also have wired smoke alarms that also have batteries and they do the same thing.
    – Gil
    Feb 4, 2022 at 0:24

1 Answer 1


If you can hear it coming from a vent, it might be elsewhere. I would keep the bathroom door closed, and during that repeating period drop whatever I'm doing immediately, and try to listen at other places where ventilation ducts pass by. This way you might be able to pinpoint more accurately where it comes from.

Also listen to nearby vents to see how strongly you can hear it. If it's definitely in the ventilation system it would help retrieving the building plans so you can see their paths.

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    Will try these ideas. Have no access whatsoever to the building plans. Feb 4, 2022 at 18:55
  • I could've sworn I posted this, I guess I didn't: depending on which country you live in, you should be able to retrieve building plans from the local cadastre or county clerk's office. This might help track down the problem (if you haven't already).
    – MiG
    Mar 30, 2022 at 21:29

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