Smoke/Fire alarm repeater?

April 8, 2014 6:35 PM

I want a device that I can attach to our front door, and if the building's alarm goes off, a signal would be relayed to an alarm outside our bedroom door. Does this kind of thing exist?

I live in an apartment style condo. When we're asleep in the room furthest from the door, it's difficult to hear the building's fire alarm if we close our bedroom door. We do have a smoke alarm in our unit that works just fine.

However, my wife doesn't want to close the bedroom door when we sleep - ever. This irks me. She's witnessed two house fires (none her fault), so I cannot dismiss her concerns.

I would like to find something to notify us if an alarm goes off in the building, even if our bedroom door is closed, or if I'm wearing earplugs to sleep.

posted by EastCoastBias to Home & Garden (11 answers total)

Is the fire alarm wired, or battery only? If they are wired, you can have interconnected alarms, which do what I think you are looking for. When they are interconnected, if one alarm goes off then they all do.
posted by Houstonian at 6:47 PM on April 8, 2014

One problem I would see with the series-wired alarms is, the condo board may not like an alarm in a unit being able to set the building alarm. Maybe they can be wired one-way? I think they have 2 extra wires, in addition to a hot and ground, for the signaling scheme.
posted by thelonius at 6:50 PM on April 8, 2014

Response by poster: @Houstonian: It's wired with battery backup. But like @thelonius said, I wouldn't want it to be bidrectional. It would be one-way.

(Mind you, if the sprinklers go off in any unit, the building alarm will go off)
posted by EastCoastBias at 7:02 PM on April 8, 2014

Imagine a device like "The Clapper" positioned in the hallway that serves as the on/off switch for a beeping noise in your bedroom, but instead of being triggered by a guy who claps, it responds to sirens of the appropriate pitch. You can build a clapper-like device with Arduino, o even simpler circuitry, so modifying to respond to alarm noise should be possible.
(links: 1,2, 3)

What would probably be simpler would be to have a photodiode instead of an audio-detector, and it's triggered by the strobe light that is (legally required to be, I believe) accompanying the alarm noise. (At least for me, I'd rather work with light than sound detection). If you did the positioning right, the strobe might be the only light bright enough to go above threshold; otherwise you'd have to select for flashing light. The downside to this is the DIY aspect. And the fact that you'd have to trigger the building alarms several times to prove that it works.
posted by aimedwander at 7:25 PM on April 8, 2014 [1 favorite]

Get two wireless, interconnectable smoke alarms. Put one in the bedroom, one in the outside hallway? There are lots on amazon. (Wireless here meaning using radio waves to communicate.)
posted by sebastienbailard at 7:37 PM on April 8, 2014

Response by poster: @aimedwander : I like that idea (regarding the arduino) I have a few around. I wondered about that, but I want to have her really trust the device, whatever it may be. If I tell her "this is what I created", she might think I'm just crazy and not trust the science behind it.

I wouldn't dare think about tripping the building alarm, but I'd hope that I could say "anything over 110dB for X seconds will trip this device".

@sebastienbailard: I doubt I would get away with mounting another smoke alarm in the hallway. I wish I could.
posted by EastCoastBias at 7:54 PM on April 8, 2014

Best answer: Firefighter here. Can you ask the condo association/building manager or what have you to mount another alarm head closer to your door in the hallway? Safety is something they should certainly be worried about. Call your local FD for help wording your request if you like, or memail me.

Also--it's safer to have your door closed in a building fire. And you have a sprinklered building!!! It reduces your risk of dying in a house fire by 82%, and protects you from fire damage so, so well. Seriously.
posted by skyl1n3 at 9:02 PM on April 8, 2014 [3 favorites]

If the building's alarms are interconnected with wires, an electrician could install one in your bedroom or living room that was connected to those of the building, if the wires or conduits permit it, and that the building's human officials are ok with it.
posted by sebastienbailard at 9:19 PM on April 8, 2014

If your apartment is designed in such a way that simply closing the bedroom door means the fire alarm is hard to hear, then that is a safety risk that is the landlord's responsibility to fix, not your job to sort out. I would follow skyl1n3's advice above.
posted by EndsOfInvention at 2:57 AM on April 9, 2014 [1 favorite]

Kidder makes WiFi units that, as I understand it, communicate so if one goes off, the all sound the alarm.
posted by SemiSalt at 8:09 AM on April 9, 2014

Best answer: It looks like they make repeaters specifically for deaf tenants (the "option A" listed here), that work basically by having a microphone or flashing-light-detector near an audio alarm, and a repeater near the bed (since the tenant is deaf, the repeater is flashing lights and vibration rather than an audio alarm.) Since I only got this far by curious googling, I'm not going to try to recommend a product, but it seems like such would exist, and that hard-of-hearing resources might be helpful. (As well as just telling your landlord that it needs to be louder).
posted by aimedwander at 11:10 AM on April 10, 2014