# Return air distance from sprinkler head



## chris kennedy (Jul 15, 2017)

I was told today that a return air opening must be 3' from a fire sprinkler head. Makes sense to me but can't find the art.

Little help please.

Thanks


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## cda (Jul 15, 2017)

It is in NFPA 13

Can give a section Monday

Another option is to use a higher temp head, if it needs to be less than three feet


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## cda (Jul 15, 2017)

Till Monday check page 15 chart


Labeled 

LoCATING RESIDENTIAL SPRINkLERS NEAR HEAT SouRCES 


http://www.vikinggroupinc.com/databook/sprinklers/residential/080190.pdf


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## cda (Jul 15, 2017)

Do you need this for

Commercial or residential??


Also what edition of 13 and 13 R are you under


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## chris kennedy (Jul 16, 2017)

Sorry, commercial.


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## cda (Jul 16, 2017)

Will look on Monday 


More than likely the link and chart above is what I will find


Which edition of 13 would you like


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## steveray (Jul 17, 2017)

I "know" it is there for detectors, not sure on sprinklers....


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## cda (Jul 17, 2017)

In the 2016 NFPA 13

Check section 8.3.2.4 and 8.3.2.5 with tables

And one option in some cases is to change the sprinkler temp to higher level


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## Paul Sweet (Jul 17, 2017)

I can see the need to locate a smoke detector a distance from a return grille, because the grille might pull air away from the detector.

A return grille is pulling room temperature air, so I don't see how it would affect sprinkler operation.


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## tmurray (Jul 17, 2017)

cda said:


> In the 2016 NFPA 13
> 
> Check section 8.3.2.4 and 8.3.2.5 with tables
> 
> And one option in some cases is to change the sprinkler temp to higher level


 That's for diffusers though. I'm not finding anything about return air openings...It makes sense you would want to locate them away to ensure that the heat is not being pulled from the area and preventing the sprinkler from discharging until the fire has increased in size beyond where a single head will be able to contain...


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## cda (Jul 17, 2017)

I guess I should read each word.

Will look again, but have not heard of a distance requirement for return air.

Unless there is a tremendous velocity, I am thinking the heat plume will activate the sprinkler, even with the hvac going


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## tmurray (Jul 17, 2017)

Probably. I'm just worried about the buoyancy of the hotter air being the one that gets removed first and is replaced by cooler air around the head.


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## cda (Jul 17, 2017)

If there is enough fire to activate the sprinkler,

There is enough fire to activate the sprinkler.

Plus you also get into spacing, there may be a sprinkler nearby that might activate, if the return air is messing things up.


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## tmurray (Jul 17, 2017)

As with sprinkler jumping, would you not have portions of the fire potentially outside of the spray of the head in this scenario? Isn't this why there are minimum head spacings? Not being sarcastic, I'm honestly asking. I know enough about NFPA 13 to be dangerous, not helpful.


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## cda (Jul 17, 2017)

I would say minimum is so one does not spray on another, depending where you apply minimum

Such as four inch minimum away from a wall

I do not think return air vents are normally a problem


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## Pcinspector1 (Jul 18, 2017)

TABLE 8.3.2.5 (C) Front of wall-mounted hot air diffusers 36".


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## steveray (Jul 18, 2017)

That table is only residential


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