Replacing a bunch of smoke detectors

[mpeirce]

Last night another of our smoke detectors started it's battery-needs-replacing beeping at 2AM. It was especially fun since I accidentally pulled down one of two smoke detectors that is tied into our alarm system (it wasn't the unit beeping, but 2AM...) so it set off the house alarm and our monitoring company called. Fun at 2AM...

We've had the house for 18 years now and it's (past) time to replace the 9 smoke alarms that came with the house. We do know that at least the one by the kitchen still detects smoke ;-)

I was set to buy a six pack of the First Alert 9210 wired + battery units on Amazon along with three First Alert SC05CN Wired + battery smoke + CO detector units.

The 9210 are basic ionization sensor smoke alarms, while the SC05CN's add a carbon monoxide sensor and the smoke sensor is photoelectric (supposedly better). I'd put one of these on each floor.

But today I was at Costco and noticed they had sealed battery First Alert units that are also photoelectric for only a $1 more than my six pack 9210's.

How do people feel about sealed battery vs replaceable batteries. Sealed seems better to me, but what do I know?

Likewise, does anyone really know if photoelectric sensors are better than ionization sensors?

Thought I'd ask before I bought these.

 

[GrayHare]

Can the sealed battery be replaced after it wears down? If not, you'll have to replace the whole unit in the future rather than just the battery.

 

[Senator]

Kidde has a recall on hard-wired combination CO/Smoke detectors. I just replaced ~25 of them.

Go to their website, anyone can buy the combo units for 50% off, free shipping. Just click the correct link. If you have the right dates, they are free.

If the sealed units have a 7-10 year battery life, it's time to trash the detector anyway.

 

[skipro33]

Something to consider is what the wiring in the house is like. If you buy a detector that fits the same plug that is already in place, it will make it a lot easier to swap out. I added on to my house and my electric contractor recommended one from Home Depot. Worked great with the rest of the house's alarms in that, when it was tripped, all the alarms go off.

 

[Senator]

Something to consider is what the wiring in the house is like. If you buy a detector that fits the same plug that is already in place, it will make it a lot easier to swap out. I added on to my house and my electric contractor recommended one from Home Depot. Worked great with the rest of the house's alarms in that, when it was tripped, all the alarms go off.

All the hard-wired detectors I have ever replaced had a new wire plug to replace the existing plugs, if needed. Just wire black to black, white to white.

 

[jonat]

The "sealed battery" models use a lithium (not lithium-ion) battery. They should indeed last until the detector needs replacement for the sensor. But that's not for hardwired detectors. (I do use lithium batteries in my hardwired detectors so they don't go beep at night...)

There are adaptors to switch among brands of wired detectors. I have seen them at Home Depot.

 

[SH09022016]

Ionization alarms are designed for "fast flame" detection where Photoelectric are for smoldering fires. Ionization alarms usually react a little faster. Ideally you should have a mix of both types, say Ionizations in the bedrooms and Photoelectrics in the hallways, etc...

 

[RobbieB]

My small house uses 1 combo detector hard wired and lifetime battery backed up. Toss and replace every 10 years.

 

[Bamaman]

Building code often requires smoke detectors to be linked to where it one goes off, they all to off. And they will be 110 volt units with 9 volt battery backup. Unfortunately, such detectors are of very low quality with 5 units coating only $25.

I once had a pit bull and those smoke detectors just about drove him crazy. He would have a fit and start tearing up upholstery when alarms went off. My detector wiring had a short and I had to unhook them all.

I replaced all my detectors with better quality Kidde units that were battery powered and not linked. They too do the job.

 

[RobbieB]

I think mine cost forty bucks each.

 

[omni550]

And if anyone wants to know why the smoke detectors always start chirping at ~2am....

 

[omni550]

FYI, Florida passed a law a couple of years ago that mandates that all new smoke detectors sold in the state must be of the "sealed battery with 10-year life" variety. Someone told me that sometimes renters will remove a 9-volt battery from a smoke detector to power a toy or something...and forget to replace it. And a missing battery in a smoke detector would be discovered after a fire.

As mentioned upthread, after 10 years of collecting household dust, a smoke detector NEEDS to be replaced...whether of the 9-volt or sealed battery type.

I have one in my condo living room that is often tripped whne I'm cooking (browning or toasting something often sets it off). I'm looking to replace it with a photo-electric type (which is supposedly less sensitive to cooking-type emanations).

omni

 

[FUEGO]

And if anyone wants to know why the smoke detectors always start chirping at ~2am....

And here I was thinking my smoke detector had malicious intent. Makes perfect sense though it seems to be closer to 4-5 am here. When working, that meant it went off 1-2 hours before my alarm went off. AKA just long enough for me to get back to sleep before the alarm clock sounds.

I think I'll be upgrading to the lifetime battery model next time ours dies. I think our smoke and CO detectors die after the 7 to 10 year period anyway. Our previous one did right at the 10 year mark of owning the house (presumably I installed the unit right after buying the house). This time around I marked the date of installation/activation on the back of the unit so I'll know it's hit the 10 year mark when it starts going crazy this time around.

 

[mpeirce]

Great feedback. Thanks!

 

[skipro33]

All the hard-wired detectors I have ever replaced had a new wire plug to replace the existing plugs, if needed. Just wire black to black, white to white.

Not saying they don't, just saying it's a lot easier if they are the same. Plug-n-Play instead of killing a breaker so you don't accidentally fry yourself while standing on a ladder and falling in the process. Might take several breakers if detectors are not all strung from the same power source. Then there's the rewiring with the wire nuts to remove and replace that plug, doing from a ladder and having to look up at the ceiling. I know that makes me a bit dizzy. If you have anything more than 8' ceilings, it gets to be even more of a pain. I have 23' cathedral ceiling in the great room area, 12' ceiling in the loft, 10' ceiling in the kitchen and 9' in the bedrooms. Even with 8' ceilings multiply times the number of detectors through out the house and it's just easier if the new units have the same plug as the old units.

 

[brett]

Some of ours will be up for replacement. I plan to purchase sealed units at costo. Perhaps even the dual units that also detect CO2.

We currently have smoke/fire detectors and CO2 detectors.

 

[jonat]

Some of ours will be up for replacement. I plan to purchase sealed units at costo. Perhaps even the dual units that also detect CO2.

Nit: CO, not CO2.

The sensors in CO detectors don't last as long as the smoke sensors - usually replacement after seven years is recommended for those.

 

[Senator]

Not saying they don't, just saying it's a lot easier if they are the same. Plug-n-Play instead of killing a breaker so you don't accidentally fry yourself while standing on a ladder and falling in the process. Might take several breakers if detectors are not all strung from the same power source. Then there's the rewiring with the wire nuts to remove and replace that plug, doing from a ladder and having to look up at the ceiling. I know that makes me a bit dizzy. If you have anything more than 8' ceilings, it gets to be even more of a pain. I have 23' cathedral ceiling in the great room area, 12' ceiling in the loft, 10' ceiling in the kitchen and 9' in the bedrooms. Even with 8' ceilings multiply times the number of detectors through out the house and it's just easier if the new units have the same plug as the old units.

Great point, although unless it's the same model number, the plug will likely be different. Even with the same model number, it could be different.

I just got done changing 25 of them. All were Kidde, being replaced with new Kidde units. I had to change about 1/2 of the plugs.

And I never switched a breaker off... I did them all live, and it was pretty easy. IN my rentals, I do change switches and many outlets live too rather than switch off all the tenants appliances.

 

[ERD50]

FYI, Florida passed a law a couple of years ago that mandates that all new smoke detectors sold in the state must be of the "sealed battery with 10-year life" variety. Someone told me that sometimes renters will remove a 9-volt battery from a smoke detector to power a toy or something...and forget to replace it. And a missing battery in a smoke detector would be discovered after a fire.

As mentioned upthread, after 10 years of collecting household dust, a smoke detector NEEDS to be replaced...whether of the 9-volt or sealed battery type.

I have one in my condo living room that is often tripped whne I'm cooking (browning or toasting something often sets it off). I'm looking to replace it with a photo-electric type (which is supposedly less sensitive to cooking-type emanations).

omni

Yes, since the detector has a limited life, and we now have affordable battery technology to match that life, I think sealed units make very good sense, and I'd support regulations for that.

I'd also support a regulation that all units have an easy to use short-term MUTE function. Not only is it convenient for cooking, it would result in fewer disabled alarms from these nuisance false-alarms. Instead of disconnecting the unit (or taking out the battery in the old ones) and forgetting to re-enable it, just mute it and it will return to service automatically in 5 minutes.

I got one with a mute button for our near-the-kitchen smoke alarm - so much nicer, and safer.

I've even seen ones that could be muted with a TV remote, which makes sense for ones you can't reach easily.

-ERD50

 

[mpeirce]

I'd also support a regulation that all units have an easy to use short-term MUTE function.

I mentioned the mute button to my DW and she pointed out that she can't reach most of the units.

Of course, it's not that hard to drag a chair over to reach it...

 

[upset264]

Our house built in 2010 has 8 detectors. Six smoke and two combo. They're Kidde, wired together with 9 volt battery backup. The problem I have is when there's an alarm or a low battery I can't determine which unit it's coming from. They have a tiny light that shows red or green to indicate the status but I am red/green color blind and the light is useless to me. I wish they had separate lights for ready/low battery/alarm.

Anyway one of the combo units started beeping about a week ago and I looked in the manual and a beep every 30 seconds means it needs to be replaced. Fortunately I looked on Kiddes website and found that there's a recall. I called them and they're shipping me two new combo units. All I had to do was send them a picture of the back of each of the two that are being recalled.

In the meantime I have gone around and disconnected the red wire in each of the units. I'm done with having eight alarms going off. If one goes off anywhere in our 2500 sq. ft. house I'll hear it, and I'll know where to look.

 

[GalaxyBoy]

I designed fire alarm and fire suppression systems for a living, before reaching the promised land. So this post is making me feel a bit too much like I'm back in an office.

To understand the difference in performance between ionization vs. photoelectric detectors, you have to know something about smoke. Smoke contains tiny particles, as well as various gases and hot air. When a fire is hot, the particles are small and numerous per a given volume. When the smoke cools, these particles tend to clump together so you have fewer, but larger, particles in that same volume.

Ionization detectors operate on a principle such that their signal is proportional to the number of smoke particles in the chamber. Therefore, they tend to be more sensitive to hot, flaming fires, or hot incipient fires. The smoke might not even be visible at this point. This is why that detector just outside the kitchen goes off when you almost, but not quite, burn the toast.

Photoelectric detectors have a light source in the chamber with a light sensor off-axis to the source. When the chamber fills with smoke, some light is reflected and detected. Therefore, they tend to be more sensitive to the colder smoke generated by slow, smoldering fires with those larger smoke particles.

You may have seen documentaries about people whose ionization smoke detectors didn't go off until the house was full of smoke. Years ago, there was a heat detector company that sent salesmen to people's homes to give a little demonstration where they lit a newspaper, filled a mayonnaise jar with the smoke, and set it on the kitchen table while they gave their spiel. The then took the jar of smoke to the homeowner's smoke detector (almost sure to be ionization), opened the jar and waited for the target's jaw to drop open when the detector failed to go off. This is probably a better example of why one might choose photoelectric smoke detectors, rather than heat detectors (which don't meet code as life safety devices anyway, since they respond even slower to fires as they have to wait for the temperature to rise).

Why are ionization detectors so common? Well, they're cheap and many builders see these things as annoyances they must install to get the required permits.

Ionization detectors meet the codes and standards, but for my house, I choose photoelectric.

 

[MuirWannabe]

So, this thread made me realize my 18 year old smoke detectors were probably all in need of replacement. I have 8 total in my house. Indeed, I tested one of them and it sat there happily as fire and smoke poured right into it. Well past time to replace. I appreciate this thread for giving this realization.

After reading the advice here I’ve decided I’d like to purchase sealed, photoelectric smoke alarms. Kidde seems to be the brand of choice mentioned. The model they offer that is sealed and photoelectric appears to be the P9010 series. But I find on Amazon these have terrible reviews. The complaints are about false alarms, inability to reset it without having to permanently disable it. So, I’m hesitant to purchase this model.

Can anyone recommend a model that is sealed and photoelectric? Thanks.

Muir

 

[Chuckanut]

I got some at Costco - 2 for about $20 a while back. They seem to work fine and the batteries last about a year.

 

[travelover]

I got these which are dual sensing - ionization and photoelectric. They take regular 9 volt batteries. Very happy with them over 6 years.

https://www.amazon.com/gp/product/B0007G71U4/ref=oh_aui_search_detailpage?ie=UTF8&psc=1