Replace Smoke / C0 Alarm. photoelectric vs ionization? - Canadian TV, Computing and Home Theatre Forums
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post #1 of 24 (permalink) Old 2019-07-26, 03:09 PM Thread Starter
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Replace Smoke / C0 Alarm. photoelectric vs ionization?

I hear photoelectric smoke alarms are the new thing, The other technology is ionization. does anyone with an actual photoelectric smoke alarm installed can they tell me for sure does it really work well? does it get rid of nuisance alarms when cooking or showering?

pls advise, i have to replace 3 of them in my house and im going to go with hard wired combination c02 and smoke alarms with a battery backup just incase the hydro goes out
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post #2 of 24 (permalink) Old 2019-07-26, 03:38 PM
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Photoelectric and ionization smoke alarms detect different fire conditions. Photoelectric smoke alarms detect smoke, such as given off by a slow burning, smoldering fire. Ionization smoke alarms detect the ionized gases given off by fast burning fires. Ideally, both types of alarms would be used. I've seen smoke detectors with both built into one unit but not with CO. I've noticed that CO detectors often have photoelectric smoke detectors in addition to CO detectors. In that case, I would also install an ionization detector in the same zone. Some of the newer units use RF to link alarms.

False alarms or detection failures are often caused by poor placement of alarms. Cooking, open flames (gas ranges) and high humidity can cause false alarms. Place them away from areas that may cause frequent false alarms or areas with poor circulation. Do not place then in or within 6' of bathrooms or kitchens. Do not place them directly over heating/cooling registers or air returns. Do not place them within 1' of room corners due to possible poor air circulation. Placing CO detectors in garages or near driveways (where fumes may enter the building) can cause false CO alarms. The detectors themselves often include placement recommendations in the installation instructions.
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post #3 of 24 (permalink) Old 2019-07-26, 06:39 PM
 
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Photo-electrics still go off if you produce enough smoke cooking but are far less prone.

As far as false trips due to steam/moisture go, best strategy is to locate it far enough from the bathroom.


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There's another better reason to use photo-electric.

FIY...

Both types have been around at least since the 1960s.

Photo-electric type alarms are better overall than ionization. ion units provide a slightly earlier warning when there's a flaming fire. The difference is measured in seconds.

They're vastly superior at detecting visible smoke from soldering fires.



Both types provide adequate escape time for fast flaming fires but if you have ionization and have a smoldering fire, you're screwed. An ion alarm may go off half an hour or more after a photo-electric unit will.



Of course, it's still best to have both sensors. If you must choose one type and one unit is serving an entire floor, make it photo-electric.

Ionization only alarms only caught on due to deceptive marketing and a low manufacturing cost. They claimed that they give very early warning because they detect invisible particles of combustion before any visible smoke is produced. In the real world smoldering fires don't give off enough tiny invisible particles to trip off ion sensors until the room is completely full of smoke and uninhabitable.

The UL smoldering tests are done with natural material like cotton and the type of smoke put out by modern petroleum based (think foams) furniture when smoldering is very different. So the alarms still pass the tests.

Some local jurisdictions have banned ionization only alarms. Australia is changing their testing standards and existing units being made now probably won't pass.

If you don't believe me, watch some tests.
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post #4 of 24 (permalink) Old 2019-07-27, 02:55 PM Thread Starter
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okay great advice, photo electric it is.

Another question. I'm going to be removing the battery powered smoke alarm in my basement and change it to a hard wired model, that is tied into direct hydro. my basement has ceiling tiles, what is the best way to secure the smoke alarm to a ceiling tile? i tried googling but to no avail, im sure they use ceiling tiles in schools and offices so there must be a simple way? otherwise if not, i will have to mount the junction box to the top of the vertical wall
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post #5 of 24 (permalink) Old 2019-07-27, 03:29 PM
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Put some thin metal on the back side of the ceiling tile, drill holes through the metal, tiles and use bolts/nuts instead of screws?

Attach the detector to the metal strapping instead of the tile using metal screws or bolts/nut? May need a spacer to keep tiles level.

Put wood on the back of the ceiling tile and use wood screws long enough to go through the tiles into the wood?

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post #6 of 24 (permalink) Old 2019-07-27, 05:43 PM
 
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Hard wired smoke alarms must be installed on junction/fixture boxes.

So it would be done the same as a light fixture when there's a drop ceiling. You'll need to build something to mount the box to, have the box go through the ceiling tile.

Honestly, if you're not planning on interconnecting it with other alarms and permits aren't involved, just put another battery unit. You can get battery units that interconnect wirelessly.

For those you can just put a piece of thin wood on the other side and put screws through.
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post #7 of 24 (permalink) Old 2019-07-27, 10:14 PM
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The 120v fixture box must be attached to a joist or use another approved method. Attaching it to a ceiling tile is not permitted. It will be necessary to remove or cut the ceiling tile to install the wiring and connect to the other alarms so I suggest that someone qualified be hired to do the job. Installing this type of wiring in a residence is not an easy or cheap job and, by law, it must be done correctly.

We purchased wireless connected battery units a couple of years ago and wouldn't do it any other way. Connected units is safer because a CO or smoke warning sounds on all units when one detects an issue. Wireless CO/smoke detectors can be purchased in sets of two or three at a lower price than purchasing separate units.
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post #8 of 24 (permalink) Old 2019-07-28, 04:04 PM Thread Starter
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Thanks, I understand the difficulty in installing the smoke alarm to a ceiling tile with all the extra reinforcing required. Yes im an expert in electronics and wiring but if theres another simpler way i will do that instead. And there is. I spoke to some professionals on the weekend and they advised me to install it on a wall up high in my basement which i can do cus there is an unused junction box already and its got steady hydro. The second option was told was to install it on the existing ceiling joist junction box and use a special baffle ceiling tile thst they use for vents or ducts so the air flows thru and yeah you can see the ceiling but its not a total eyesore but it will work.

So i have two options to do and some time to think about it. I dont care at this time about inter connecting them as long as they work and my family is safe.
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post #9 of 24 (permalink) Old 2019-07-28, 06:55 PM
 
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Inter-connecting is very beneficial when the alarm is in the basement.

Though if you aren't renovating the rest of the house you can get a hard-wired alarm with wireless interconnect.

Are the rest of the alarms in the house already hard-wired?

When was the house built? Most built in the last 30 to 35 years were done with hard-wired, interconnected alarms. In the early 80s in ontario they only required one hard wired alarm outside the bedrooms.
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post #10 of 24 (permalink) Old 2019-07-29, 01:12 PM Thread Starter
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I can easily hear the basement C0/2 and smoke detector from my bedroom on the upper level. so interconnecting is NOT a must but it's more of a nice to have, I might consider the wireless inter-connecting models regardless, but then it would only benefit me if i replace all 3 smoke/co2 alarms at the same time, otherwise i will have a mix and mash of different brands and products. either way, when you buy a previously owned house you NEVER know and should never trust what the original homeowner left you with, he could easily say it's 3 years old, and in my case the upstairs wired smoke alarm was 23 years old instead and was giving all kinds of false alarms.

I have existing junction boxes on all 3 floors which i can wire them into so needing an electrician or a permit is likely not necessary. Really its only the basement one which is the one that urgently needs to be replaced, right now there is no C02 alarm there at all, I can re-locate one of the other ones there for the time being because I heard the furnace room is likely the main source of C0/2 leaks
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post #11 of 24 (permalink) Old 2019-07-29, 02:07 PM
 
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yah the alarms all have to be the same make.

Normally homes built with hard-wired on each floor have the interconnect built right in.

With the exception of nest (which i would avoid), don't know of hard-wired alarms with wireless interconnect made to communicate with other hard-wired units.

There are hard-wired alarms from first alert which have a wireless bridge feature: ie their wireless alarms communicate with the hard-wired unit which sends signal over existing inter-connect line.
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post #12 of 24 (permalink) Old 2019-07-29, 04:44 PM
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The prewired units probably have an extra conductor for the interconnect. I would try to tie into that if possible. Interconnected alarms are much more than a nice have. An alarm in the basement may be audible when awake but not heard while sleeping, especially if affected by CO or smoke. That's why alarms near the bedrooms are mandated. It can make the difference between escaping or never waking up.
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post #13 of 24 (permalink) Old 2019-07-29, 04:47 PM
 
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bad idea to interconnect alarms not approved to work together.
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post #14 of 24 (permalink) Old 2019-07-29, 06:56 PM Thread Starter
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So to clarify when my house was built. Only one smoke alarm was mandatory so the builder only put one junction box upstairs hallway and had one smoke alarm pre-installed. The previous home owner before me must have put those junction boxes himself at some point later for who knows what? so yeah they're there but they are not interconnected together by hardwire heck they r not even on the same circuit

Thanks for all the great advice. I think im just gonna replace all 3 floors with the same combo units that inter connect wirelessly. Better to be safe than sorry. Its a small price to pay for safety
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post #15 of 24 (permalink) Old 2019-07-29, 07:24 PM
 
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I'm read really bad reviews about kidde alarms with 10 year sealed battery backup - false trips, loss of connection, backup failing before it's time. Their wireless ones with replaceable backup seem to be ionization only.

The first alert stuff seems to be good. Less selection though, doesn't look like they have hard-wired available with monoxide.
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