Forum Thread

Flaky smoke detector?

Dr. J 25,038 3,353 August 12, 2015 at 05:00 AM
Well my smoke detector system decided to wake me up at 4:30 AM just for the hell of it I guess. My place is 3 floors (incl basement), 4 BR so 7 detectors. Smoke only, no CO (I purchased standalone CO units when I bought the place in 2010, 1 per floor). I raced around the house making sure there was no smoke, and all was clear.

The system went off for appx. 20 seconds, then turned off for 10 or so then back on. The second time it went off I pulled the detector in the upstairs hallway (the green light was flashing steadily) and the alarm immediately turned off. I didn't realize this but apparently a steady flashing light on the units means they have stored alarms (since the last reset), a good troubleshooting tool I guess. I replaced the battery, reset the alarm (by pressing the test button), reinstalled it and it's been fine since. I also pulled the alarm on the 1st floor which was also flashing steady and replaced the battery, although that's the alarm that always goes off when stuff is burning in the kitchen.

FWIW, the units are all 10 years old or so; the 2nd floor unit I pulled down to replace the battery had a manuf date of 03/05. I'd been thinking of replacing them due to yellowing anyway.

Looking online it seems old detectors can be flaky - not work at all or work "too" well (as is my case). Just wondering if this is prevalent at all?

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#2
We have to replace them after 10 years.. Per Fire Dept
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#3
Funny how these things always die in the middle of the night.

General rule is to replace every 10 years. Partially due to the decay of americium 241 inside. The beep code your getting does mean something. Contacting the manufacture might be one way to figure out exactly what it means. The other is just to replace them since they are due too.

Buy dual sensing units http://www.asecurelife.com/best-smoke-detector/. They improve the false positive ratio a lot and protect against both types of fire.. Personally I found these much easier to get in battery only units vs the AC backup ones. In hindsight I would buy the more expensive AC powered ones and not have to replace the expensive 9V batteries every year. One more tip, if you have a vaulted ceiling or other difficult spots, and do end up with battery powered units, spend the extra money and buy a lithium powered 9V battery. They last for 10 years are not much more money and it's so nice not to have to borrow a giant ladder to change the battery every year.
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#4
Quote from LiquidRetro View Post :
Funny how these things always die in the middle of the night.

General rule is to replace every 10 years. Partially due to the decay of americium 241 inside. The beep code your getting does mean something. Contacting the manufacture might be one way to figure out exactly what it means. The other is just to replace them since they are due too.

Buy dual sensing units http://www.asecurelife.com/best-smoke-detector/. They improve the false positive ratio a lot and protect against both types of fire.. Personally I found these much easier to get in battery only units vs the AC backup ones. In hindsight I would buy the more expensive AC powered ones and not have to replace the expensive 9V batteries every year. One more tip, if you have a vaulted ceiling or other difficult spots, and do end up with battery powered units, spend the extra money and buy a lithium powered 9V battery. They last for 10 years are not much more money and it's so nice not to have to borrow a giant ladder to change the battery every year.
Thanks for the great reply.

1) I am not getting a beep code. The green light on the unit has 3 modes apparently - steady on is everything is OK; long-period flashing indicates to replace the 9V battery; short flashing indicates a stored alarm - IOW the detector has gone off since the last reset. I didn't realize this until this AM when I took the unit off and read the back, but it's good to know and also useful to determine which detector was set off since in the AC system they all go off

2) I am looking into a combo smoke/CO unit just for the hell of it but I'd say they are twice as expensive as the smoke only units. I DO have 3 CO detectors, one on each floor that I installed 5 years ago.

3) You'd assume AC units would be prevalent but I'd say less than half of the offerings are AC (e.g. whole house).

4) Fortunately none of the units are in an area inaccessible by a simple step ladder

5) Along with the smoke/CO combo, I haven't found one of these that's also a dual detector for smoke. Most appear to be P (photo) (vs. I which is ionization).
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#5
Quote from Dr. J View Post :
Thanks for the great reply.

1) I am not getting a beep code. The green light on the unit has 3 modes apparently - steady on is everything is OK; long-period flashing indicates to replace the 9V battery; short flashing indicates a stored alarm - IOW the detector has gone off since the last reset. I didn't realize this until this AM when I took the unit off and read the back, but it's good to know and also useful to determine which detector was set off since in the AC system they all go off

2) I am looking into a combo smoke/CO unit just for the hell of it but I'd say they are twice as expensive as the smoke only units. I DO have 3 CO detectors, one on each floor that I installed 5 years ago.

3) You'd assume AC units would be prevalent but I'd say less than half of the offerings are AC (e.g. whole house).

4) Fortunately none of the units are in an area inaccessible by a simple step ladder

5) Along with the smoke/CO combo, I haven't found one of these that's also a dual detector for smoke. Most appear to be P (photo) (vs. I which is ionization).
Lots of dual sensing units available on amazon. I had a hard time finding them at the local store. Looks like they have AC units available now too fore a few $ more. http://www.amazon.com/s/ref=nb_sb...e+detector

If you have the CO2 units already I don't think I would spend the extra to go smoke+CO2 I would rather go dual smoke and leave the CO2 you have. Don't know what the life span on them are.
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#6
It seems old detectors can become flaky because their electrolytic capacitors go bad and start leaking electric current (not chemicals), but I doubt this is the problem if the capacitors are American, Dutch (Philips, or NXP), or Japanese. Another possibility is a contaminated sensor, but you may be able to clean off its metal plates with Q-tips wetted with distilled water. Wipe once, toss the Q-tip into an outdoor trash can, and repeat with a new Q-tip. A tech licensed on commercial fire alarm systems recommended this, but he also recommended doing everything outdoors, in case the coating on the radiation source was broken. I tried this with an old smoke detector when it started to chirp randomly, and afterward it stopped, yet it still seemed to be very sensitive to smoke (canned aerosol and burning cotton string).

I've seen combination ionization smoke detectors and CO detectors, and I'v eseen combination ionization smoke detectors and photoelectric smoke detectors, but I've never seen a triple combination ionization smoke/photoelectric smoke/CO detector. You really want both types of smoke detectors because with very smokey fires with little flame, the photoelectric type will typically react in half the time as ionization detectors. OTOH photoelectric detectors are close to completely useless for low-smoke flaming fires.
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Last edited by larrymoencurly August 12, 2015 at 12:40 PM
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#7
Quote from larrymoencurly View Post :
It seems old detectors can become flaky because their electrolytic capacitors go bad and start leaking electric current (not chemicals), but I doubt this is the problem if the capacitors are American, Dutch (Philips, or NXP), or Japanese. Another possibility is a contaminated sensor, but you may be able to clean off its metal plates with Q-tips wetted with distilled water. Wipe once, toss the Q-tip into an outdoor trash can, and repeat with a new Q-tip. A tech licensed on commercial fire alarm systems recommended this, but he also recommended doing everything outdoors, in case the coating on the radiation source was broken. I tried this with an old smoke detector when it started to chirp randomly, and afterward it stopped, yet it still seemed to be very sensitive to smoke (canned aerosol and burning cotton string).

I've seen combination ionization smoke detectors and CO detectors, and I'v eseen combination ionization smoke detectors and photoelectric smoke detectors, but I've never seen a triple combination ionization smoke/photoelectric smoke/CO detector. You really want both types of smoke detectors because with very smokey fires with little flame, the photoelectric type will typically react in half the time as ionization detectors. OTOH photoelectric detectors are close to completely useless for low-smoke flaming fires.

Yeah I've read that the i and p types of detectors are really suited to 2 entirely different types of fires. I went ahead and ordered 7 new dual sensor units. What got me thinking to replace them a few months ago was the terrible yellowing that the plastic does in these units, makes them stick out like a sore thumb on a white ceiling.

Is there special disposal due to the radioactive source?
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Quote from Dr. J View Post :
Yeah I've read that the i and p types of detectors are really suited to 2 entirely different types of fires. I went ahead and ordered 7 new dual sensor units. What got me thinking to replace them a few months ago was the terrible yellowing that the plastic does in these units, makes them stick out like a sore thumb on a white ceiling.

Is there special disposal due to the radioactive source?
That requirement was dropped over 20 years ago, and now you can just dump them in your regular trash.
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#9
co2 detectors have expiration dates on them. the ones linked to our alarm system actually fault shortly after that exp date.

like lr said above its funny how they fault in the middle of the night.
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#10
replace them,they say buy photo ones


your problem could be roaches or other bugs that come out at night,also a window open will bring in dirt


a red light shows you which smoke went off
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#11
I don't know how these odds happen, but 9 of the last 10 times I've had smoke alarms chirp or false alarm have been in the middle of the night. One time I had paint fumes set off a photoelectric smoke alarm tied to my alarm system. That one was a real pain to reset / deal with.

I think a lot of smoke detectors actually contain an internal 10 year countdown timer. Some may actually detect when they're failing. On hardwired smokes, you do have to find which one is the problem to get them to stop. On many, the test button is also a hush button which in addition to stopping an alarm, will silence chirps for 8-12 hours. Electrical interference or connection problems can also set them off. On a somewhat related note, in my college dorm, if you held the light switch in between on and off you could set off the smoke alarm for the entire building.
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Last edited by jkee August 12, 2015 at 06:53 PM
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#12
Quote from Dr. J View Post :
2) I am looking into a combo smoke/CO unit just for the hell of it but I'd say they are twice as expensive as the smoke only units. I DO have 3 CO detectors, one on each floor that I installed 5 years ago.
Any mass market CO detector is virtually useless imho. Standard CO detectors are programmed to alarm when levels have remained 75 ppm (or greater) for 1 to 4 hours. Thus, you could have a slow CO leak of 60ppm for 5 years and while it slowly kills you, your detectors will remain silent. Imho, rather than get a bunch of these, you are far better off getting a couple low level detectors and placing them in areas where there is a reasonable possibility of a CO leak (near the furnace, dryer, stove, gas fireplace, etc.). Kidde makes one [kidde.com] that will alarm at 20 ppm. Better still, Defender makes one [defenderdetectors.com] that alarms at 5ppm. I personally have the latter in my home.
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#13
Quote from ManUpOrShutUp View Post :
Any mass market CO detector is virtually useless imho. Standard CO detectors are programmed to alarm when levels have remained 75 ppm (or greater) for 1 to 4 hours. Thus, you could have a slow CO leak of 60ppm for 5 years and while it slowly kills you, your detectors will remain silent. Imho, rather than get a bunch of these, you are far better off getting a couple low level detectors and placing them in areas where there is a reasonable possibility of a CO leak (near the furnace, dryer, stove, gas fireplace, etc.). Kidde makes one [kidde.com] that will alarm at 20 ppm. Better still, Defender makes one [defenderdetectors.com] that alarms at 5ppm. I personally have the latter in my home.

I pulled this blip from the alarms I have [kidde.com]:

Per UL 2034 requirements, the CO sensor will not alarm to levels of CO below 30 ppm and will alarm in the following time range when exposed to the corresponding levels of CO. 70 ppm CO Concentration 60 - 240 minutes 150 ppm CO Concentration 10 - 50 minutes 400 ppm CO Concentration 4 - 15 minutes
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Quote from Dr. J View Post :
I pulled this blip from the alarms I have [kidde.com]:

Per UL 2034 requirements, the CO sensor will not alarm to levels of CO below 30 ppm and will alarm in the following time range when exposed to the corresponding levels of CO. 70 ppm CO Concentration 60 - 240 minutes 150 ppm CO Concentration 10 - 50 minutes 400 ppm CO Concentration 4 - 15 minutes
Yeah that's what concerns me. I don't know what timeframe is required by that specific detector to alarm for < 70ppm, but we know that at <30ppm it will never alarm. The rationale behind it is that the powers-that-be claimed that calls regarding low level CO were consuming too many resources, so they raised the limits for the alarm in order to reduce the number of calls.
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#15
you really only need co detectors where you have a co source so if you have no heaters in the bedrooms you can skip it thére basement for furnace or where you have a fireplace or gas dryer or stove.

important to replace every 10 years check code to see if it has changed,one per floor and one in each bedroom.

I picked up a couple of multi packs from home depot.
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