How old is your detector? Our fire department told me that they have a life expectancy of about 10 years, mainly because grease, dust, etc. in the house environment can settle on and disrupt the sensors, leading to false alarms, or failure to detect.

If steam from the bathroom could reach the hall, such as the door being open, that will set it off.

That is a hardwired smoke detector. However, the Firex G6 has been discontinued and they recommend replacing them. You may have more of these elsewhere in your house and they are supposed to communicate with one another, but that evidently tended to fail, so they suggest updating to a newer alarm system. (I think most of these were installed back in the late 1990s, so it's time anyway.)

EDIT FWIW, in my townhouse I have one hardwired detector and one battery-operated one.

Thanks to you all for replying. :)

bpathome, I'm pretty sure all my smoke detectors are original to my house, so they're about 25 years old. ::hanging head in shame::

snookums2, seriously? Steam? I do shower with the door open and this SD is close to the bathroom door, but it's not particularly cold today and there was minimal steam, if any at all. My mirrors never steam.

writersblock, wow, no battery?!! That would explain why, once when I was checking out the wiring of my hall ceiling lights and turned off the power at the box, the SD went off. I have three of these: living room, hall, master bedroom.

I guess I need an upgrade. Who does this kind of thing, a regular electrician?

Wait, if mine is not battery-operated, then what caused it to go off when I turned off the power at the source? What was powering the alarm?

My fire department does free smoke alarm checks and also changed the battery for one on our vaulted ceiling that we can't reach. It's easy to change them if you're good on a ladder, so maybe they wouldn't mind plugging in new ones and testing them for you.

We should probably upgrade ours too. Every now and then it beeps but hasn't in quite awhile.

How long did it take the kitties to come out from under the bed?

benjesbride, yes, a blessing.

mayflowers, hmmm, maybe tomorrow I'll call the fire department and get their advice. I'll bet at the very least they'll be able to give me some names of installers, because this isn't something I can do myself (fear of electricity). LOL, you know my cats too well. I have no idea where they went. Me? I'm standing naked with a towel wrapped around my head, dripping water everywhere. I'm sick with an awful cough and I was not very happy at that moment. I lugged my 6-ft. ladder into the hallway and suddenly the cats reappeared because Yay! Ladder!!!

Linelle, it may have some kind of small internal battery, but there is no user-replaceable battery in those, and you are way overdue for replacement (says she with the archeologically perfect first generation First Alert). Actually unless you are the kind of person who vacuums your smoke alarm every week when you check it (yeah, I don't do either, either), it could just be dust inside it that set it off. I would look for smoke detectors that are hardwired with a battery backup, since you are already set up for wired ones.

EDIT Sorry this happened when you're sick. Isn't that always the way?

We did have a false alarm and unfortunately we weren't home to stop it so it triggered a call to the FD. Turned out to be a spider in the smoke alarm in the basement triggered it. Go figure.

Ooh, Annie, a bug alarm! I need one that summons the exterminator, or at least someone wearing shoes to stomp on it. (Oh, now I'm going to hear about that. Yes, I step on ants.)

I had the FD here too when steam from the shower tripped it. I had the bathroom door open. I relocated the alarm to be sure it didn't happen again.

I just talked to someone at Mister Sparky's. I was going to set up an appointment, but they charge $59 to come out for an estimate. Is that typical? I know that if I use them it gets applied to whatever it costs. I told them never mind. I'm probably stupid for doing that, but I just wasn't in the mood, without knowing what the whole job would cost anyway. If I don't get any better leads from my fire department, I'll call Mister Sparky back.

Snookums, you must have really steamy showers!! So, is it anything airborne?

I think that might have been my old shower which did make for a steamy bathroom. I see reports of others having it happen out on google. I forget what the sensors can pick up.

Right, anything that can cloud the sensor's view of the air, so smoke, dust, steam, fog, cobwebs, insects, pet dander (I don't know about you but I seem to find it everywhere so inside a detector would not surprise me!).

Do you have a handyman that you like? This should easily be something he (or she) can do for you.

Here's a list of possible triggers:

http://www.brkelectronics.com/faqs/oem/no-smoke-present-mro

Does your alarm have carbon monoxide as well? We had alarms quite a bit at night with our alarms and we took out the batteries but they were also hard wired.

it turned out that we have CM alarm too so now we just open the door for fresh air and the alarm goes off immediately. We also had the house checked for gas leak but it was because the house is too tight.

You guys are the best! I'll figure it out tomorrow. It's actually a relief to me that I need new detectors. I've suspected this for a long time, but I've been in denial.

beachem, why would fresh air set your alarm off? I don't think my house is too tight. I consider this episode an aberration but a blessing in disguise.

Mains alarms ( carbon monoxide, smoke, intruder etc) always have battery backup. It's there so you still have the protection available if there's a power cut. So that's why it went off when you cut the mains supply. It's an alert

Linelle, call your friendly fire department today. Last I checked, they work on weekends. :P

That's what I'd do if I were in your shoes. I don't know the first thing about buying new smoke alarms so I'd want their advice anyway. Ours looks just like yours with the plug but I don't know if that's not recommended any more.

Oh....I know MY kitties too well! Whenever I put the exhaust fan on high, they assume I'm burning steak and take off running, even though it's been a year or more since I last set off the smoke alarm.

Mine is hard wired also and it also has a battery backup in it that takes a 9 volt battery. I called a hardware store about 5 years ago with the model number of the one that was previously installed (it was about 15 years old) and they ordered the replacement one for me which was an updated version. It's very easy to replace yourself as long as you get the correct one. Just pull out the pin section closer to the alarm and push the new one in.

Somersetlass, but...if it's likely I don't have a battery in mine, what would power the alarm if the power was turned off?

Mayflowers, I guess the FD does work on weekends. But I'd hate to bother them during the football games. :) I'm in sick mode today so I think I'll feel better doing business tomorrow. If this thing goes off again, of course, I'll change my tune. Bringing the vacuum in from the garage has a similar effect on my cats. Ugh, I didn't even squeegee my shower tiles, do you think civilization will continue?

So, I assume I want power + battery backup, right? Is CO necessary?

You need to call your security company first to let them know you will be tampering with the equipment. I'm not sure about changing the battery in detectors but with other devices any tampering will send an alarm out to them.

snookums, I don't have a security company.

@linelle the fresh air turned off the alarms as the Carbon monoxide got replaced with oxygen from outside.

beachem, I completely misread "we just open the door for fresh air and the alarm goes off immediately." I thought the fresh air made the alarm go off, as in set it off. :p

"So that's why it went off when you cut the mains supply"

yes, this. the break in the current would make it beep.

yes, linelle... I think civilization is now over!

recently my kitchen battery alarm beeped while I was cooking something. it was an attempt to burn something... I didn't flick the exhaust to higher level quick enough. At the beep, I up'd the exhaust and had no more beeps. or burned food at that time.

the battery in the lead alarm should fuel the attached alarms.

a good handyman or electrician could change them out easily. I'd shut off the breaker at the panel tho.

oh, then be sure to lite a fire close to them to be sure they are connected properly and working....

Okay, so I need to replace three smoke alarms. Should I buy them myself and have someone install them, or does the installer supply them? Mister Sparky, who wants $59 to just come by and tell me what they charge, has a van/truck full of them.

Prices for alarms have quite a price range. Would something like this (3 pack) be okay? Home Depot

We have a hard-wired system too, but they do have backup 9-volt batteries - so when ours started beeping recently and wouldn't stop, we had to disable all of them by taking them down and removing the batteries. We replaced the batteries and it seems to be fine now but I have no idea what would have happened if only my DD had been home (she couldn't reach the ceiling even on the tallest ladder). It was scary.

P.S. I"m sick with the same cough as you seem to have. Unfortunately, I feel horrible even after a week. I hope you do better!

SJ, I'm sorry you're sick. It showed up middle of last week as a minor cold but then morphed into a horrible wracking cough. The Kaiser doc on-call told me it lasts about a week, except for some and it lasts for 2-3 weeks. Sounds like they're talking about you, my friend. Friday and Saturday were horrible, but I feel so much better today. I need to lay off the codeine because it was making me feel icky. They also gave me a QVAR inhaler. Anyway, my cough has improved considerably. I hope you're on the mend soon.

Either hardwired or good batteries should suffice, right? If you have power and the alarm beeps, is it telling you it's time to replace your batteries? Even if it's hardwired and receiving power?

It should be easier, and less scary, to be able to service these things. As it so happens, the alarm that went off is on a 9-ft. ceiling and accessible by ladder. The other two are on walls near the apex of a 13-ft. vaulted ceiling. It's out of my reach, at least on a ladder I'm willing to trust. Of course people shouldn't be disabling them and then forget about them, but they should be easier to maintain.

Why do you need Mr. Sparky to install wireless detectors? I would contact the FD to buy their recommended alarms. I think, as mentioned above, they are happy to help keep people safe by installing them and changing batteries. I would also trust their knowledge far more on the most effective locations to place them in your house, for fire and easy maintenance that doesn't affect performance. They understand the way smoke travels. You shouldn't just install them willy nilly. Who knows with Mr. Sparky.

snookums, my current detectors are hardwired. I'm a moron when it comes to wiring and fear electrocution like you wouldn't believe. I don't necessarily need Mr. Sparky, but he was the first hit I got when I googled smoke alarm installers. I'll call the FD tomorrow when their business office opens and ask for their advice. I agree that they probably want me to have ones that function well and are in the correct locations.

They will also know what to do with the wires! I wouldn't trust a Mr. Sparky. Been there done that (not that company, specifically).

Mister Sparky may have a big mark-up on them. My BIL is an electrician and he calls the stuff he provides "gravy" because of the mark-up. They've lived well off of that gravy.

I showed DH the photos. We have Firex too and you just plug in the new if the plug is the same. You'd put on the new mounting plate and new detector but he doesn't know if the plugs are all the same, in which case you'd have an electrician change the plug.

Did you find the battery? Ours is on the face of the detector. You slide the compartment open.

I put my ladder away. :) When I was up there this morning, I gave a tug on the plug and when it didn't give easily, I stopped. Fear of frying. I'll ask the FD what brands they recommend, then probably call an electrician.