TheAlarmTech.com

Duct Detector - 101

Supervisory or Alarm? myself and everyone I have spoken to makes them alarms

NFPA72 Tells you how to mount it.

90A defines a need for duct detectors downstream of all filters, supply fans with capacities greater than 2,000 cfm.
The same goes for those of return fans with a capacity greater than 15,000 cfm.
Also Duct-mounted smoke detectors are required in each return duct inlet that serves more than one story for systems with a capacity of greater than 15,000 cfm.


Q&A GOOD STUFF - http://findarticles.com/p/articles/mi_q ... _n8851155/
INFORMATION SHEET - http://www.lasvegasnevada.gov/files/duc ... elines.pdf
Duct Application - http://www.systemsensor.com/pdf/A05-1004.pdf
The Efficacy of Duct Smoke Detection - http://www.fpemag.com/archives/article. ... d=35&i=195

I spoke to a HVAC guy and asked him "how do you know the CFM's of a unit"
more then a few times someone has asked me "do I need a duct detector on my HVAC unit", if it's over 2,000 CFM, YES

HVAC units do not have any ratings or info on CFM's.
HVAC units are rated in tons and each ton is equal to 400 CMF's

So a 5 ton unit is equal to 2,000 CMF's, so it needs a duct detector

to give you an idea on the different size and tons of units, a large house unit is 4 tons.

Here in my area, the AHJ requires duct detectors to report as a supervisory condition on all new installations. Section 606 of the International Mechanical Code is where this requirement comes from. I believe the change came in the 2003 edition.