Smoke Detectors

[edro]

Our house (we have lived here 3 months) is 15 years old and has the original hardwired smoke detectors installed.
They started going off and it is a pain in the ass to turn them off.
If one goes off, they all go off.
The only way we could get them to consistently stop was to unplug them from the ceiling and remove the backup batteries... all 9 of them!
So now we have no detectors at all.

I ordered 9 exact model replacements from the manufacturer and will replace all of them.
I didn't want to swap out the bases or wiring pigtail by switching brands.
The old ones say "Replace by 2009".
I guess we were already on borrowed time.

I hope the new ones don't give any false alarms...because it is pretty stressful when all 9 go off at once and you can't figure out which one is the culprit.

This is my first experience with hardwired detectors.
I see no benefit other than if a fire happens on a different level, you can hear the alarm. I think we would hear it anyway.
I always thought hard wired versions didn't need batteries (no replacement needed), but no... hard wired versions still use batteries, which die and need replaced.

Stupid safety...

 

[NoCreativity]

Our house (we have lived here 3 months) is 15 years old and has the original hardwired smoke detectors installed.
They started going off and it is a pain in the ass to turn them off.
If one goes off, they all go off.
The only way we could get them to consistently stop was to unplug them from the ceiling and remove the backup batteries... all 9 of them!
So now we have no detectors at all.

I ordered 9 exact model replacements from the manufacturer and will replace all of them.
I didn't want to swap out the bases or wiring pigtail by switching brands.
The old ones say "Replace by 2009".
I guess we were already on borrowed time.

I hope the new ones don't give any false alarms...because it is pretty stressful when all 9 go off at once and you can't figure out which one is the culprit.

This is my first experience with hardwired detectors.
I see no benefit other than if a fire happens on a different level, you can hear the alarm. I think we would hear it anyway.
I always thought hard wired versions didn't need batteries (no replacement needed), but no... hard wired versions still use batteries, which die and need replaced.

Stupid safety...

We moved into a new build last year. Within a month the backup battery died on the basement alarm. That reminds me, guess it's time to replace some batteries.

Million dollar question: Why does the low battery chirp always start in the middle of the night?

 

[SOFTengCOMPelec]

If it makes you feel better, I think you need to replace them every 10 years, anyway.

Source

A Smoke Alarm's Life Expectancy

October was National Fire Safety Month, and according to Invensys Controls, smoke alarms should be replaced every 87,000 hours, or about 10 years. In addition, carbon monoxide alarms should be replaced every five years.

 

[SOFTengCOMPelec]

Million dollar question: Why does the low battery chirp always start in the middle of the night?

My understanding is that there is an accurate voltage monitor in smoke detectors, and when the voltage drops (possibly under a brief test current load), the battery warning signal trips/starts.

Lower temperatures tend to make batteries weaken (lower voltage, under load), probably because chemical reactions usually slow down, as the temperature drops.
Your home will tend to be colder in the middle of the night (in many places/Countries), unless you have constant temperature heating on 24/7.

So, it makes sense to me.

 

[edro]

We don't have carbon monoxide detectors. I'll take my chances...

 

[NoCreativity]

My understanding is that there is an accurate voltage monitor in smoke detectors, and when the voltage drops (possibly under a brief test current load), the battery warning signal trips/starts.

Lower temperatures tend to make batteries weaken (lower voltage, under load), probably because chemical reactions usually slow down, as the temperature drops.
Your home will tend to be colder in the middle of the night (in many places/Countries), unless you have constant temperature heating on 24/7.

So, it makes sense to me.

Thanks for the explanation. I swear they space the chirp out just enough to give you time to fall back asleep before the next one.

 

[SOFTengCOMPelec]

We don't have carbon monoxide detectors. I'll take my chances...

http://www.consumerreports.org/cro/news/2014/04/when-to-replace-an-older-smoke-alarm/index.htm

Q. I have two homes equipped with hard-wired smoke alarms, original equipment now about 17 years old. The alarms respond appropriately to the test buttons. But the instructions on a battery-operated alarm say it should be replaced in 10 years. What about mine?—William Pohlmann, Manitowoc, WI

A. The life expectancy of smoke alarms is generally 10 years, after which point their sensors can begin to lose sensitivity. The test button only confirms that the battery, electronics, and alert system are working; it doesn’t mean that the smoke sensor is working. To test the sensor, use an aerosol can of smoke alarm test spray that simulates smoke. But even if the 17-year-old smoke alarms in your homes can still detect smoke, we recommend replacing them with new models.

Thanks for the explanation. I swear they space the chirp out just enough to give you time to fall back asleep before the next one.

(I don't know exactly), but I think they calculate the spacing's between the chirps, so that the somewhat run down battery, will be able to chirp for something like one month. So that if you happen to be on a 2 or 3 week vacation, when the battery starts fading, you will still be alerted by it.

 

[tsiunltdus]

The reason hard wired smoke detectors still require a battery is due to the fact of an electrical failure. That way the smoke alarm is still able to function correctly. The life of smoke detectors is 10 years on most models.

 

[shabby]

9 smoke detectors?!? Geez that must be an eye sore, i have 1 per floor in my house.

 

[NutBucket]

Well, suppose to be one per floor plus one per bedroom and in the kitchen.

For some reason I have two in the hallway. Not sure why that was done.

 

[Zivic]

I wired my house (built in 76) with detectors when I moved in, in jan of 2007. I have a carbon+smoke on each floor (3) and smoke in each bedroom (3). I recently had to replace all detectors in the house about 6 months ago. they all started failing after 8 yrs (manufacture date of 2006). they would do the constant chirping. all within a few months of each other. They don't last forever so you are just doing home maintenance

 

[MongGrel]

I wired my house (built in 76) with detectors when I moved in, in jan of 2007. I have a carbon+smoke on each floor (3) and smoke in each bedroom (3). I recently had to replace all detectors in the house about 6 months ago. they all started failing after 8 yrs (manufacture date of 2006). they would do the constant chirping. all within a few months of each other. They don't last forever so you are just doing home maintenance

The wife has two she bought years ago, multi ones.

I do not think I've ever opened them up...

 

[boomerang]

I just had to replace all five after buying a second residence. I was able to find some that came with adapters to work with the existing connector.

One was chirping with a low battery but when pressing the test button only one of the remaining four made a nearly imperceptible buzz. The rest made no noise at all. They were all date coded from 1997.

 

[shabby]

Well, suppose to be one per floor plus one per bedroom and in the kitchen.

For some reason I have two in the hallway. Not sure why that was done.

Ah must be a US thing, here in canada its only 1 per floor.

 

[Zivic]

Ah must be a US thing, here in canada its only 1 per floor.

from my understanding you need one per floor and one in each bedroom.

 

[utahraptor]

One per bedroom can buy you a few precious seconds or even minutes if the doors to those rooms are closed. If the bedroom doors are all in the same close hallway and the doors are left open one in the hallway should suffice.

 

[boomerang]

Ah must be a US thing, here in canada its only 1 per floor.

They've changed the requirements through the years and I'm not even sure there's a national or even state policy on their placement. It may be local.

 

[Greenman]

They've changed the requirements through the years and I'm not even sure there's a national or even state policy on their placement. It may be local.

It varies a lot even city to city here in the land of fruits and nuts. Most places it's one SD in each bedroom, one in the hall, and one C02 sensor on each floor. One city near me requires a commercial low voltage smoke alarm system with a backup battery and control box. The sensors they require drift over time and require a yearly cleaning. I expect most people will just shut the stupid thing off and put in battery powered smoke detectors as the systems aren't the least bit user friendly.

 

[Red Squirrel]

On subject of hard wired smoke detectors, how do they alert the other ones, is it just a dry contact? Reason I ask is because I'd like to set up some smoke detectors on my monitoring system so if I'm not home and one goes off I'll get an alert on my phone. Worse case scenario I might probe around a regular one till I find a spot I can throw in a transistor and contact point, but rather not modify one if I don't have to.

 

[Scarpozzi]

I recommend getting these where you think you may need CO2:
http://www.brkelectronics.com/product/SC9120B

I buy them from eBay and usually save $10-15 off my local electrical supply house.

They have non CO2 detectors as well...these are pretty good quality, if you care.

 

[SOFTengCOMPelec]

CO = Carbon Monoxide = Dangerous gas which can kill you = E.g. Faulty Gas appliances

CO2 = Carbon Dioxide = Gas we breath out (Respiration) / Soda/Fizzy drinks gas = Relatively SAFE, unless concentration is somewhat high

Some people are talking about "CO2" detectors ?

I think they mean CO detectors.

 

[WilliamM2]

I wired my house (built in 76) with detectors when I moved in, in jan of 2007. I have a carbon+smoke on each floor (3) and smoke in each bedroom (3). I recently had to replace all detectors in the house about 6 months ago. they all started failing after 8 yrs (manufacture date of 2006). they would do the constant chirping. all within a few months of each other. They don't last forever so you are just doing home maintenance

The newer ones, especially with carbon monoxide detectors will start beeping when they have reached their life expectancy. They are programmed to do it. My old ones were good for 7 years, the replacements I got last year are good for 10. It's right in the manual.

 

[Howard]

I hope you got photocell-based detectors. Apparently the normal cheaper kinds don't go off until there is already a lot of smoke.

 

[SOFTengCOMPelec]

I hope you got photocell-based detectors. Apparently the normal cheaper kinds don't go off until there is already a lot of smoke.

My understanding is that it depends on the type of fire.

Source

What types of smoke alarms can I buy?
There are many brands of smoke alarms on the market, but they fall under two basic types: ionization and photoelectric.
Ionization and photoelectric smoke alarms detect different types of fires. Since no one can predict what type of fire might start in their home, the USFA recommends that every home and place where people sleep have:
Both ionization AND photoelectric smoke alarms. OR
Dual sensor smoke alarms, which contain both ionization and photoelectric smoke sensors.
There are also alarms for people with hearing loss. These alarms may have strobe lights that flash and/or vibrate to alert those who are unable to hear standard smoke alarms when they sound.

Source for following Quote, about types of fire detected

Ionisation alarms

These are the cheapest and most readily available and are very sensitive to flaming fires (ones that burn fiercely such as chip-pan fires). Ionisation alarms will detect flaming fires before the smoke gets too thick.

Optical alarms

These are more expensive and more effective at detecting slow-burning fires (such as smouldering foam-filled furniture or overheated wiring). Optical alarms are less likely to go off accidentally and so are best for ground-floor hallways and for homes on one level.

For the best protection, you should install one of each. However, if you can’t have both, it’s still safer to have either one, rather than none at all. Whichever model you choose, you should make sure that it meets British Standard 5446, Part 1 (BS 5446-1) and ideally also carries the British Standard Kitemark.

 

[stormkroe]

Ah must be a US thing, here in canada its only 1 per floor.

Actually, it's one CO and Smoke alarm in every bedroom or within 5 meters of the bedroom, one smoke for every 15 linear meters per floor of a house, one in any mechanical room containing a solid fuel burning heater (wood, coal, pellets, etc.), one in any mechanical room containing any fuel burning appliance if that mechanical room is located outside of a dwelling unit. Any floor containing sleeping quarters or fuel burning appliance must have CO detection at the same requirements as smoke alarms.