# Duct detector ??



## Rollie73 (Sep 19, 2010)

How do you plan on monitoring it? What is it going to trip or signal if senses smoke in the duct?

Since some of them come with a NO/NC set of contacts I'm willing to bet that you _can_ do anything you want. 

I have no idea if there would be an NEC or NFPA issue in your area but I _think_ I would have an issue in my area as most duct detectors are only listed for use with their corresponding fire alarm panels/systems.


----------



## walkerj (May 13, 2007)

Yes. 
It needs a power source and will only shut down the unit. 
If there is no monitoring, no one will know there is smoke.


----------



## sbrn33 (Mar 15, 2007)

I was thinking I could just set of a local alarm or outside bell. I probably should just quote a small panel though. Just seems kinda stupid.


----------



## mgraw (Jan 14, 2011)

All the duct detectors I have used have remote annunciators available.


----------



## NacBooster29 (Oct 25, 2010)

Yes. They can. 
I have seen them monitored by a bas.


----------



## wildleg (Apr 12, 2009)

we have installed that scenario several times in office supply stores where FA wasn't called for but for some reason they required duct detectors. seems to me we just ran power to the detectors, and a remote indicator/test key switch to nearby location. HVAC guy wired the detector in to the shunt off terminals on the units.


----------



## mgraw (Jan 14, 2011)

wildleg said:


> we have installed that scenario several times in office supply stores where FA wasn't called for but for some reason they required duct detectors. seems to me we just ran power to the detectors, and a remote indicator/test key switch to nearby location. HVAC guy wired the detector in to the shunt off terminals on the units.


Duct detectors are required based on the CFM of the system. It has nothing to do with whether a fire alarm system is present or not.


----------



## Rollie73 (Sep 19, 2010)

You guys sure have some different requirements than we do. :thumbsup:


----------



## 13/2 (Apr 30, 2015)

Yes you can. goto page 7 "https://www.systemsensor.com/en-us/Documents/DH400ACDCIHT_Manual_I56-0991.pdf"]https://www.systemsensor.com/en-us/Documents/DH400ACDCIHT_Manual_I56-0991.pdf[/URL]


----------



## 13/2 (Apr 30, 2015)

yes you can. look up your detector's wire diagram. There should be different scenarios 
for different types of applications.


There is no reality. Only perception.


----------



## GrayHair (Jan 14, 2013)

Since they are always connected to the fire alarm system, *if present*, we tend to forget that a duct detector's primary function is to shutdown the air handler(s).


----------



## bduerler (Oct 2, 2009)

mgraw said:


> Duct detectors are required based on the CFM of the system. It has nothing to do with whether a fire alarm system is present or not.


This is a very true statement. Less than 2000 cfm no duct detector required. 2000 to 9999 one on the supply duct. 10000 plus one on supply. The other on return


----------



## LARMGUY (Aug 22, 2010)

GrayHair said:


> Since they are always connected to the fire alarm system, *if present*, we tend to forget that a duct detector's primary function is to shutdown the air handler(s).


Most of the time though the FA only monitors the duct detector in supervisory mode.


----------



## bduerler (Oct 2, 2009)

LARMGUY said:


> GrayHair said:
> 
> 
> > Since they are always connected to the fire alarm system, *if present*, we tend to forget that a duct detector's primary function is to shutdown the air handler(s).
> ...


True but that depends on the AHJ. Down here they like them to go into alarm and to have an RTS151 led annunciator tied into each duct detector


----------



## mgraw (Jan 14, 2011)

bduerler said:


> This is a very true statement. Less than 2000 cfm no duct detector required. 2000 to 9999 one on the supply duct. 10000 plus one on supply. The other on return


That would depend on what code the AHJ follows.
NFPA 90A requires a detector in units 2,000 to 15,000 cfm's in the supply.
IMC requires a detector in units 2,000 cfm's or larger in the return.


----------



## sbrn33 (Mar 15, 2007)

I t don't matter much any more. Now they have to sprinkle the building. So The small FA panel it is. 
Just stupid they have to do all this crap for a 100'X85' maintenance shed.


----------



## GrayHair (Jan 14, 2013)

sbrn33 said:


> I t don't matter much any more. Now they have to sprinkle the building. So The small FA panel it is.
> Just stupid they have to do all this crap for a 100'X85' maintenance shed.


If you furnish the fire panel, make sure it is listed for Sprinkler Supervisory Service.

Making them supervisory was gaining popularity with fire departments around here when I retired. Cuts down on thr number of false runs when cool weather arrives.


----------



## bduerler (Oct 2, 2009)

mgraw said:


> bduerler said:
> 
> 
> > This is a very true statement. Less than 2000 cfm no duct detector required. 2000 to 9999 one on the supply duct. 10000 plus one on supply. The other on return
> ...


Once again this is true. Code plays a huge role.


----------

