Problem with system sensor duct detector

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tyha

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we have a conventional panel with 6 duct detectors wired on 2 ckts. each DH 100 detector has a light and key switch. one of the detector lights will not go off, even when the system is normal and the duct detector is not in alarm it still has power comming off of the the contacts in the duct to the light and keeps it on. the supervisor relay is correct and doesn't open until the key is turned or smoke is detected and then it resets to normal except for the light will not go off.
 
tyha said:
we have a conventional panel with 6 duct detectors wired on 2 ckts. each DH 100 detector has a light and key switch. one of the detector lights will not go off, even when the system is normal and the duct detector is not in alarm it still has power comming off of the the contacts in the duct to the light and keeps it on. the supervisor relay is correct and doesn't open until the key is turned or smoke is detected and then it resets to normal except for the light will not go off.
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Your saying the "Sig" terminal is hot all the time?


If your sure the the wiring to the RTS (Remote Test Switch) is correct and not back feeding the sig terminal from the RTS then it is time to buy a new duct detector.
 
yeah it wired just like we have wired ever one before but it just doesn't make any sense why the other contacts in the detector are going back to normal but this one isn't
 
tyha said:
just doesn't make any sense why the other contacts in the detector are going back to normal but this one isn't
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There are a lot of electronics even on the DH100, I just replaced two of them at a Lowe's about a week ago that would randomly go in and out of trouble. Found no reason for it but the new detectors fixed the issue.
 
Hey, don't take this wrong, we all make mistakes.

Are you sure the connections and jumper at the RTS are made correctly?

Make the wrong connections at the RTS and you could get that symptom.

Is it a brand new install or did it used to work?

If it never worked I might also try swapping in a known good RTS as it could have an internal problem
 
tyha said:
yeah it wired just like we have wired ever one before but it just doesn't make any sense why the other contacts in the detector are going back to normal but this one isn't
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Are there parts that you can swap with a properly-functioning detector system, one at a time, until you narrow it down?
 
LarryFine said:
Are there parts that you can swap with a properly-functioning detector system, one at a time, until you narrow it down?
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With the DH 100 there is a PC board and a detector head, the board is easily removed and swapped. Never tried swapping the heads.

The RTS are generally very cheaply made junk and I would defiantly try a swap of that if it never worked.

Duct smokes are flaky, I went to a large Mall after a lightning strike, a little more then 250 troubles on the FACP, almost everyone was a duct smoke that did not survive the lightning strike.

CHA-CHING $ :smile:

Last week one of the other guys replaced 26 FACP mother boards and probably 50 other misc addressable devices in a low income housing development, that was another storm.
 
I actually changed out the rts without even checking to see that there was still power on the terminals comming from the duct. It is definetly not the rts. I know it is the terminals for the duct and I am just going to get another one. The fire marshal is comming at 3 tomarrow. ducts can be a pain in the but plus this is a conventional system not addressable so we had to narrow it down when we had a trouble plus the stupid panel kept showing ghosts when we would clear something. it was just a knightmare.
 
The DH100 duct detector has a reed switch on the cover that allows the removal of the cover for cleaning and testing. After twenty minutes it produces a trouble light at the detector.
It maybe that the cover is not sitting tight.Here is part of the spec sheet with the info. The DH 100 detector by system sensor is also branded under alot of other Fire Alarm control manufacturers

The DH100 Innovair Series four-wire duct detectors offer
innovations in installation, operation and maintenance. The
unit is capable of controlling up to ten (10) air handling systems
when interconnected with up to nine other detectors. A
unique, patented ?cover missing? signal provides twenty
minutes for testing and maintenance before creating a trouble
signal if the cover is still missing.Anintegral filter system reduces
dust and residue effects on the detector and housing.
Continuous Electronic Monitoring ensures that the sensor
board is installed, powered and operating above its minimum
sensitivity level

Hope this helps
 
Thanks for the pictures Bob, now that I see it, we ripped 9 of these out of 3 new McQuay RTU's, replaced and re-engineered the mounts to accept a ETS DH, worth the trouble before removing the factory DHs 3 had issues 2 constant alarms and one DOA
 
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