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Thread: Smoke alarms

  1. #1
    Len Couey's Avatar
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    Default Smoke alarms

    Inspected a home today, had just checked the alarms by manuel test and worked ok. Turned on the heat at air handler and the wiring shorted out and burned in two. Smoke alarm did not respond, checked with smoke test later (after scare from heater wiring buring up) they did not work these are all wired togeather one goes all go. Just checking to see what could be the problem. The same guy that did the splicing on the Heating unit also installed the smoke alarms. I checked four of the units using smoke test and none of them worked. If you manuely tested all seemed to be ok.

    Any thought or Ideas.
    P.S The Heat power cords were Dryer type plug in ??? is this ok

    Thanks
    Len Couey

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  2. #2
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    Default Re: Smoke alarms

    "Inspected a home today, had just checked the alarms by manuel test and worked ok. Turned on the heat at air handler and the wiring shorted out and burned in two. Smoke alarm did not respond, checked with smoke test later (after scare from heater wiring buring up) they did not work these are all wired togeather one goes all go. Just checking to see what could be the problem. The same guy that did the splicing on the Heating unit also installed the smoke alarms. I checked four of the units using smoke test and none of them worked. If you manuely tested all seemed to be ok."


    There are two main types of smoke detectors, Ionization and Photo electric.
    A simple description of how they work is as follows:
    Photo electric detectors "see" smoke when particles of smoke enter the sensing chamber.
    Ionization detectors "detect" the products of combustion, NOT smoke itself.
    Your everyday, garden variety smoke detectors are most often ionization.
    With ionization detectors you could have a considerable amount of smoke, but very little "products of combustion" .
    So with ionization detectors the "smoke test" you performed may not cause an alarm. Even with photo detectors it takes a lot of smoke to set them off.
    If they worked when you pressed the test button, most likely they work fine.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  3. #3
    Len Couey's Avatar
    Len Couey Guest

    Default Re: Smoke alarms

    Rick, I had a house full of smoke from electrical arc and fire and the units did not work.???? I checked four of them with smoke cans and they did not work????

    Len C


  4. #4
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    Default Re: Smoke alarms

    Quote Originally Posted by Len Couey View Post
    Rick, I had a house full of smoke from electrical arc and fire and the units did not work.????
    How old is the house, or more importantly, how old are the smoke detectors? The smoke detectors should be replaced every 10 years.

    I checked four of them with smoke cans and they did not work????
    That's what Rick said would likely happen - smoke testing them may not cause them to go off.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Smoke alarms

    Quote Originally Posted by Len Couey View Post
    Inspected a home today, had just checked the alarms by manuel test and worked ok. Turned on the heat at air handler and the wiring shorted out and burned in two. Smoke alarm did not respond, checked with smoke test later (after scare from heater wiring buring up) they did not work these are all wired togeather one goes all go. Just checking to see what could be the problem. The same guy that did the splicing on the Heating unit also installed the smoke alarms. I checked four of the units using smoke test and none of them worked. If you manuely tested all seemed to be ok.

    Any thought or Ideas.
    P.S The Heat power cords were Dryer type plug in ??? is this ok

    Thanks
    Len Couey
    Is it possible that the smoke detectors are on the same power circuit as the AHU? Also is it possible that the smoke detectors have a set of contacts that can be used to shut off the HVAC system in the event of a fire?


  6. #6
    Len Couey's Avatar
    Len Couey Guest

    Default Re: Smoke alarms

    Jerry, they are new old home with hard wired units when you manual test they all go off. I had a home full of smoke and nothing happened.????

    Len c


  7. #7
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    Default Re: Smoke alarms

    Quote Originally Posted by Len Couey View Post
    I had a home full of smoke and nothing happened.????
    I've heard it takes A LOT of smoke to set them off, and during a real fire there is A LOT of smoke, as well as a lot of products of combustion.

    Based on what Rick said (Rick is the smoke alarm guy here), I would say that the "home full of smoke" was not sufficient in and of itself as the products of combustion Rick referred to would be minimal, and it would be those products of combustion which would trigger most residential smoke alarms.

    Once triggered, any one of them of set all others off, yes, but it is triggering that first one.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
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    Default Re: Smoke alarms

    Sometimes work at a house will create dust.
    May just need to be cleaned.
    Also
    The cheep detectors that are sold just about everywhere are not very reliable.
    I bought a few cases to install in my rental properties.
    I think the cost was about $40 for a case of 6.
    It seemed like all of them worked, but after about 6 months some would go into alarm for no apparent reason. This went on for about a year before I replaced them all.

    Anyhow, if you are in doubt, just recommend that they be replaced.

    (Why the heck does "Doubt" have a "B" in it?)

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  9. #9
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    Default Re: Smoke alarms

    Len said they worked when he pressed the test button, but did not when he use canned smoke or when there was real smoke.
    This got me to thinking,
    On the detectors I use (fire alarm systems, not the home type detectors) the test button actually does test the smoke detectors capability to detect smoke (or products of combustion). I wonder if the test button on everyday detectors do that or just sound the sounder? I'll see if I can find out more about this.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  10. #10
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    Default Re: Smoke alarms

    Len said he " had just checked the alarms by manuel test and worked ok. Turned on the heat".

    This is from BRK they make First Alert smoke detectors.
    To me it sounds like that if you test them by using the test button they are inactive for 10 minutes.

    (bold added)

    A Quick Homeowner's Guide to Understanding Your Smoke Alarms
    Test/Silence Button: This is an easy way to make sure your smoke alarm is functioning properly. Just push and hold the test/silence button until the alarm sounds. It is important to test your smoke alarms every week to make sure they are working properly. The test button is the only recommended way to test them. If any smoke alarm does not alarm during testing, make sure it is receiving power and test it again. If it still does not alarm, replace it immediately. During testing, you will hear a loud, repeating horn pattern: 3 beeps, pause, 3 beeps, pause. When testing a series of interconnected units you must test each unit individually. Make sure all units alarm when each one is tested. This button is also used to silence unwanted or nuisance alarms and reset the Latching feature. The alarm will be silenced for about 10 minutes. The alarm can be re-tested while in silence mode by pushing the test/silence button.



    And it does look like the test button actually does test the detectors capability to detect smoke.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  11. #11
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    Default Re: Smoke alarms

    On many detectors "testing" also activates the "hush" feature which would likely prevent them from going off for 10/15 minutes after testing. Any chance your fire was within that time frame?


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