smoke detector placement

[gndrod]

HVAC 101 affecting NEC

HVAC 101 affecting NEC

Has anyone here who does residential work ever been called on having a smoke detector located too close to an air duct, warm air, return air etc? When I roughed it in 2 months ago, I was told that all the HVAC rough in was complete, I come back now to trim it out and I've got diffusers in the ceiling 8 inches from the devices. Manufacturers specs say 36" away from any HVAC, anybody here ever run into this problem? I would assume the building official will make the call, smokes fall under their domain here in MI.

Hi nizak,

I guess the mechanical guys got to you after your installation. There are two answers. The first is not a good one for you and the sheet rocker and that is to move the SD 3' away from the supply register. The second answer is up to the AHJ to approve a supply register deflector that allows the air to be redirected away from the SD.

General discussion,
This is residential that is being addressed so I must add further that bedrooms do not have HVAC Return Air CAR's. The CAR is usually in one and rarely two common locations (large home may use split returns to furnace plenum) that are located in the wall well below the ceiling at floor level.

A modern residential CAR return duct is nowhere near a ceiling SD using proper HVAC design unless it is an industrial or commercial configuration.
As badabing mentions, the register in the ceiling wall is not a return air duct, but a transom vent that can be closed or opened to balance heat from the room into a main hall where the return air duct is located. I hope this clears up some of the confusion. rbj (see post #20 ref)

 

[gndrod]

Third option

Third option

nizak,

Have the HVAC sub move his duct. This becomes a GC call and may involve 'extras' for you if the mechanical guy came later and the GC decides that the SD must be relocated. rbj