Smoke detector

[edward wadsworth]

I know a smoke detector needs to be at least 3' away from a supply register. Does that same rule apply to a return

 

[JDB3]

The inspectors that I know want it to be.

 

[GoldDigger]

The inspectors that I know want it to be.

It makes it easy for them to inspect without having to distinguish between a return and a supply.
But the motivation on the distance from a supply register is to avoid "clean" perhaps outside air from washing locally generated smoke away from the smoke detector.
That risk does not exist for a return register, although there may be a concern with smoke being diverted away from drifting toward the sensor

 

[edward wadsworth]

That's exactly what I thought thank you

 

[gadfly56]

I know a smoke detector needs to be at least 3' away from a supply register. Does that same rule apply to a return

NFPA 72, either the 2007 or 2010 edition, mentions only the supply register. I also didn't find anything in the 2009 ICB or 2006 IMC. Local AHJ's may have additional requirements.

 

[ron]

NFPA 72-2010
29.8.3.4(6) Smoke alarms and smoke detectors shall not be installed within a 36 in. (910 mm) horizontal path from the supply registers of a forced air heating or cooling system and shall be installed outside of the direct airflow from those registers.

Return is ok

 

[LIM]

Look at 2013 NFPA 72 17.7.4.1 and also annex for that reference.