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Which Smoke Detectors for ELK
Posted 02 August 2012 - 01:22 PM
To work with the ELK, would I need a SC Polarity-Reversal Module or end of line relay?
Posted 02 August 2012 - 02:05 PM
They arent the prettiest things in the world but came well recommended by a bunch of people around here. My goal is reliability and little or no falses first, good looks a far second.
Edited by chrisexv6, 02 August 2012 - 02:05 PM.
Posted 02 August 2012 - 02:34 PM
I but I dont think the 4 wires require that (on the flipside, the 4 wires will require a power supervision relay)
The 4-wire unit also require a power reversing relay in order to have them sound in unison. The way devices work is this: the device that initiates the alarm will activate it's integral sound. AND devices that are NOT in alarm will activate their sounder when the power polarity is reversed. The reversing relay flips the power lead polarity to make all of the units sounder activate in unison.
The GE/UTC 449CSTE is a 4-wire device that has an integral power supervision relay. It makes wiring a bit simpler/easier. It looks OK. It think it's bit larger in diameter than the SS devices. But since I was replacing old GE/UTC devices, the larger diameter meant that I didn't need to paint around each of the new sensors (I minor issue....).
Posted 02 August 2012 - 03:09 PM
The 4-wire unit also require a power reversing relay in order to have them sound in unison. The way devices work is this: the device that initiates the alarm will activate it's integral sound. AND devices that are NOT in alarm will activate their sounder when the power polarity is reversed. The reversing relay flips the power lead polarity to make all of the units sounder activate in unison.....
Sorry about that, I was used to 2 wire stuff so didn't really check on the 4 wire. I know DELInstallations is a big fan of 2 vs 4 wires. Im not sure Ive ever really grasped what the advantages and disadvantages are, but either way I went with 2 wire smokes, used an 18/4 fire wire loop and used the 2 spare conductors for the heat-only detector loop.
Posted 02 August 2012 - 06:53 PM
DSC devices work from a switched negative, whereas almost every panel in NA is switched positive. If you have existing smokes or ever need to replace one, you can't install a DSC on a fire loop with other manufacturer's 4 wire units, vice versa.
DSC smokes need a zone with the response time set for higher than 1.25 seconds, otherwise they are prone to cause phantom fire troubles based on their design. The are also prone to sending a "maintenance required" signal when it is not valid.
They do not maintain the wiring continuity when power is removed, while it may not be a problem for most, when attempting to troubleshoot, it's almost impossible without removing the detector itself.
There have been multiple issues with devices slipping past QC with bad drift compensation or sensitivity sections on their board...what this means is the detector will either false or not trip the zone. Only way this can be verified is either field testing and metering sensitivity using an appropriate canned smoke/tester.
The reversing relay in question will fire only on a pulsed temp 3 input, unless they made some major redesign changes to the circuit within the last year or so.
I wouldn't install multiple 4 wire fire zones with a reversing relay...it's an exercise with a lot of inherent issues, such as fire reset and multiple zones going into trouble when an alarm occurs or is reset after an alarm. If you go by the book, it looks like a good idea, however executing it successfully and being practical for usage are usually mutually exclusive items.
Posted 27 February 2013 - 07:09 PM
So I am also about ready to put smokes on my system, (about 10). I want to be able to see which zone went off from the panel in my room, so I assume I need 4 wire, correct? Del, you state that 4 wire are problematic to install and setup?
What pros/cons do one have over the other?
Does a 4 wire have to have its own power supply, or is the M1 unit enough?
Any direction would be wonderful. I know I asked this some time ago, but cant seem to find it anywhere.
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