Smoke Detectors Inside HVAC Returns

[Al Roden]

Is there an easy was to determine if this smoke detector is specifically listed for installation inside a return air chase?

[Rick Cantrell]

Is there an easy was to determine if this smoke detector is specifically listed for installation inside a return air chase?
That is not a smoke detector, it is a siren for an alarm system.
Should not be in the ducts.
I think this is the siren in the picture.
http://intellahome.com/alarmpdfs/wave2.pdf

Plastic smokes when burned.
Even duct mounted smoke detectors are mounted outside the ducts and have a sampling tube going into the duct.

[Mark Reinmiller]

Is there an easy was to determine if this smoke detector is specifically listed for installation inside a return air chase?

It does appear to be a siren. I assume it is right next to a return-air grille. I see no harm in having it there, unless is interferes with the volume of the alarm, or the manufacturer does not permit it.