Home Forums Fire Alarm Systems Replacement for 4 wire ESL 445CT

This topic contains 4 replies, has 3 voices, and was last updated by  willbill808 6 years, 3 months ago.

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    I'm a new owner of an older '63 home with a DSC PC500 alarm panel used for fire safety only. One existing smoke/heat detector went off for no reason and they appear to be at least 15 yrs old. To reset it I had to shut down the power & pull the battery, then all was fine. I just replaced 1 detector with a GE 541NBXT. It checks out OK & system seems to work except I still cannot reset the system once the system has gone off by the usual methods (silence alarm w/ code, push reset button, enter arm code). I have to unplug the control box & unplug the battery for the system to reset. The old ESL 445CT detectors definitely have a relay built into them which I believe are sticking closed when they alarm (back cover says: contact rating listed at “1A, 30VDC or 120 VAC resistive). I still have 2 old detectors to replace. So my question is simply is the 541NBXT the correct replacement for an old ESL 445CT or do I need the “R” type (541NCRXT) with the aux relay? My current system has an upstairs horn/ siren that goes off along with the tiny chirp in the control box.My home also has a heat detector in every room that look almost like sprinkler heads. 1-1/2 in diameter plastic & stick down 2 inches with metal fin. They are 2 wire and are daisy chained together. Is there a similar replacement for these old things?Thanks in advance.DavidMadison


    DEL Installations

    The 445's didn't have anything but the alarm relay built into them.

    The one you listed is a suitable replacement, I'd check the wiring connections for errors though, since they reset by having power removed from them using the control panel.

    Barring that, there's plenty of other suitable replacements, such as the 449 CST, System sensor 4WTAB and a few others.

    Heat detectors vary. but I like either Chemtronics, Firelite or System Sensor models, application dictates unit.



    Thanks Dave!
    Any idea how old the 445's are. No date that I can tell from all the numbers. I'm assuming the other 2 should be replaced 


    DEL Installations

    From memory, I want to say there's a date code on a "store" type sticker (price style) on the units with the model and the like on it.

    445's haven't been around for at least 10 years I can remember, which is the rule of thumb for replacement.



    Glad I found this topic… I am somewhat of an expert on ESL products myself.  ;)

    The older ESL line of detectors were made from the early-mid 1980s to the late 1990s. in both 2 and 4 wire variants, being 425 and 445, respectively. There were also similar detectors sharing the same cover (here's a list of all of them!)
    -422 (2 wire)
    -425 (2w)
    -445 (4w)
    -446 (Canadian 445)
    -447 (4w)

    And yes, there is a date code on the units. It is 4 digits, usually followed by a T. The first two correspond to the year it was produced, and the latter two are the week it was produced.
    I used to have a 445CT installed in my house, too, and I replaced it with a 449CT.

    Another important point: There has been an issue with these older 445 series detectors "going bad"… most of the time that is not the case. The sensing chamber on these units is designed in such a way that makes it especially prone to false alarms from dust. Frequent cleaning can prevent this, but by the time they fail, the 10 year life would have already expired, and it is time to get a new one anyways.

    A lot of info, but hey, I like to help out as much as possible.

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