this post was submitted on 19 Jan 2024
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Fire Alarm

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Hey all,

We moved into a new house about 3 years ago and have been plagued by nuisance alarms ever since. They happen most often in the middle of the night, but aren't uncommon in the daytime.

I have:

  • Replaced all the old hardwired detectors with new battery-only ones thinking it might be caused by EMI.
  • Ruled out insects crawling into the detectors.
  • Sealed the electrical boxes thinking it might be dust from the attic.
  • Installed an excellent filter system in the HVAC.

Other random info:

  • Only the ones on the second floor go off. There are five upstairs and two downstairs.
  • I'm pretty sure one (and only one) of the false alarms was caused by humidity from a shower.
  • Seems like they're happening less often since I installed a new HVAC system, but that could be due to less dust or due to smaller temperature swings (less of a setback at night).

I think at this point I want to get some fancy multi-criteria alarms, ones that are specifically for reducing your nuisance alarm rate. Also for increased capability, though - one of my coworkers just narrowly escaped a housefire with his wife and dog. Their fire alarms failed to go off and he was only woken by the sound of the flames.

Any suggestions for multi-criteria alarms that work with hardwired 120VAC three-pin connections?

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[–] ultranaut 1 points 10 months ago* (last edited 10 months ago) (1 children)

Are they being triggered unexpectedly or are they doing the low battery chirp? How long are they in use before they go off?

I've recently been dealing with a similar problem. With mine they chirp at night, seemingly at random. I ultimately changed the batteries on all of them, or I thought I did until one chirped again. Now I want to replace the alarms.

[–] Omacitin 1 points 10 months ago (1 children)

Full-on alarms, not the low-battery chirps. I think the first incident after I replaced the old detectors happened in less than a month. They're the 10-year sealed style, anyway.

Did you replace them with alkaline or lithium 9V batteries? In my limited experience the alkaline batteries last less than a year before the low battery chirps start again. If your house is significantly cooler at night, battery voltage might drop enough to start the chirps, also.

[–] ultranaut 1 points 10 months ago

Interesting. I would consider getting an air quality sensor to see if you can measure anything going on that might be triggering it. I've encountered fire alarms that are extremely sensitive or seem to have variable sensitivity, especially in humid conditions.

I checked and mine are all First Alert 9120B and I did use alkaline. Next time around I'll grab lithium, thanks for the advice.