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  1. #1
    Join Date
    Sep 2009
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    6

    Default Heat detectors/alarms

    I searched the board, and saw no posts about this.

    I have a 25-year-old house, with AC wired smoke detectors and (what I assume to be) heat detectors located in pairs around the house (5 of each). One of the smoke detectors was false alarming (even though I vacuumed it, etc.) and since they looked pretty ancient, I went through the house and replaced all the smoke detectors with wired units with battery backups. I alternated around with combo ionization/carbon monoxide detectors and photoelectric detectors. So, all's good there - I know they're new, they look nice, and I know that they work.

    Now I still have these 5 ancient (and f-ugly) heat detectors, that I'm not sure even work.

    How important is it to have heat detectors, especially if each one is sitting right next to a smoke detector anyway? Should I A) replace them (at ~$25/ea) or B) remove them, cap off the wires in the junction boxes, and make a cosmetically acceptable repair (a flat plate on the wall to cover the holes or repair the drywall).

    On a related note, it looks like there's one sprinkler head in the ceiling of the kitchen (it looks like a little round button about 1" around and 1" tall - no spindly things sticking out of it though. Looks like maybe something pops out of it?), but I have no idea how this is hooked up and I see no sensor near it. How do I figure out what this really is and if/how it works? Do these sense by themselves and then start spouting water, or do they get a signal from somewhere else?

  2. #2
    Join Date
    Feb 2009
    Posts
    693

    Default Re: Heat detectors/alarms

    Your set up sounds like something I’ve never heard of and fire alarm is a part of my gig.
    Seems odd that you would have heat detectors located adjacent to the smokes unless they were used to trip the sprinkler system. Yet, that seems odd as well with the sprinkler head in the kitchen with no adjacent heat detector. No other sprinkler heads?
    Typically heat detectors are just a dry contact device which close a set of contacts on a rapid rate of temp rise or at a fixed set point. If that is the case for you then the heat detectors are tripping something else like a fire control panel or maybe a solenoid valve.

  3. #3
    Join Date
    Sep 2009
    Posts
    6

    Default Re: Heat detectors/alarms

    There isn't anything that looks like a sprinkler head anywhere else except in the kitchen.

    Of note, the smoke detectors were not wired to each other (that third yellow wire was not connected to anything on any of them).

    I haven't taken apart the heat detectors yet.

    The house does have an alarm system (also not functional) with a box in the basement. Maybe (?) at one point the heat detectors would signal some company (ADT, etc.) if they went off? If the heat detectors are connected to each other, maybe that's a good theory (maybe they were added after the house was built, and someone figured to steal the wiring from each smoke detector to put another junction box adjacent for the heat detectors). Do these monitoring companies (ADT) use heat detectors for their service, or why wouldn't they respond to smoke detectors (or do those false alarm too much).

    Anyway - do you see any problem with just dumping all these heat detectors?

  4. #4
    Join Date
    Feb 2009
    Posts
    693

    Default Re: Heat detectors/alarms

    Ah, the plot thickens………
    I would then guess that the heats were part of the panel alarm system and installed at a later point in time. But, I very much doubt they use power from the smoke detectors though. I would also guess that a pair of wires leaves the alarm panel and loops between all the heats. You will probably find a resistor on one of them at the end of the loop.
    If they are tied to the alarm panel and you have no intention of using the panel then the heat detectors are pointless and non- functioning.
    When the alarm panel was installed the install company probably sold the home owner on the idea that if no one was home to hear the smoke alarms and there was a fire no one would know until flames were coming out of the house.
    Seems a little odd that the line voltage smokes are not interlocked with the third wire as that was “Code” even 25 years ago.

  5. #5
    Join Date
    Sep 2009
    Posts
    6

    Default Re: Heat detectors/alarms

    Thanks a ton, man. I'll take off one or more of the heat detectors and see if the wiring gives me a clue as to what is going on.

    I also thought it strange that the smokes weren't interconnected, but there certainly wasn't any other wire coming into the boxes/area to which to attach the third wire.

    Now if I could figure out that do-kickey on the ceiling of the kitchen ...

    Also (maybe you know) if I disconnect the heat detectors, what do I do with the dangling ends of the wires? Can I just leave them all in wire nuts in the box and cover the box with a plate? (I've since learned I can't drywall over it because you're not allowed to hide junction boxes in this way).

  6. #6
    Join Date
    Feb 2009
    Posts
    693

    Default Re: Heat detectors/alarms

    Can not help much on the sprinkler thingamajig………
    If my assumptions are right (Bet they are.) I’d flip a coin and say you have a 50/50 shot at even finding junction boxes behind the heats. Would bet you will find something that looks more like doorbell wiring. That said the heats are just closing a set of contacts. They require no power and they are closing a signal loop that operates at 12 or 24volts. Kill the loop at the source by disconnecting it at the panel and bury all the wiring you want. Nothing in the Code against it.

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