smoke detector placement

Status
Not open for further replies.
radiopet said:
Its 3' from ducts ( return and supply ) and ceiling fans also.

That is what I thought as well and how it is enforced by the FDs here, but the language in NFPA 72 does not back that up.
 
Here in Charlotte the smokies must be 3' away from air ducts and air returns. Also if there is a fan in the room the smoke detector must be 5' away from the fan box. I've never had an issue relative to bathroom placement although I can see where that might be as issue. Also it is required that the smoke detector be 12'' form the highest point in the room unless a fan prohibits that, than it will be 5' from the fan box. Crazy stuff.

Also, as per the instructions on one smoke detector brand, I think it was FireX, if the ceiling drops below 18'' (like a doorway but no door there) than that is considered a separation and you should have a smoke detector on both sides. I read that a few years back so not sure if it's still in there.
 
iwire said:
That is what I thought as well and how it is enforced by the FDs here, but the language in NFPA 72 does not back that up.
Can someone post the exact text of the NFPA 72 on that?

I'm just a little confused, because Mac's citation doesn't match the one I was looking at that seemed to apply, but I couldn't see the bottom of that page.
 
georgestolz said:
Can someone post the exact text of the NFPA 72 on that?

I'm just a little confused, because Mac's citation doesn't match the one I was looking at that seemed to apply, but I couldn't see the bottom of that page.


Yes, other than saying "my inspector makes me do it", or "supply means return too", no one has proven to me that a smoke detector must be 36" from the return. My inspectors DON'T require 36" from return (only supply, as its written in the code).
 
edit: had already replied to that particular post


Anyway, George, here is the exact text of 2007 NFPA 72

11.8.3.5(6)
Smoke alarms and smoke detectors shall not be installed within a 914mm (36 in.) 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.

any questions? :)
 
Last edited:
I have a question regarding the smoke detector placement. Today we were wiring a new home and the home does not have 'traditional' return vents. The Entire house is fed from 1 air handler (basement, 1st flr, 2nd flr and 3rd flr). It's 1 main trunk line that goes up to the 3rd floor with branches off on each floor to the rooms. There's no actual "return" air vent. There are however Vents in each room that lead from the room to the hallways. (basically it's a duct that goes nowhere.) Are those considered return vents? The stairwell as I understand it, is the actual return air. The home is designed by the owner of an Heating/AC company and this is his design for a "Green" house. Now can i place my smoke closer to those "vents" (the ones that go from the room to the hallway) in the ceiling then a traditional vent or no? Kind of stumped me today. And since there's a big discussion about the smokes close to the vent, how would one handle the entire stairwell, where I need one at the top of each... I mean... it is a return air vent afterall :)
 
georgestolz said:
Yeah, where's the bit about ceiling fans? I remember seeing that.

Sorry, I thought you just wanted the supply vent code. It said the SD had to be 36" from the paddle fan as well.
 
badabing said:
I have a question regarding the smoke detector placement. Today we were wiring a new home and the home does not have 'traditional' return vents. The Entire house is fed from 1 air handler (basement, 1st flr, 2nd flr and 3rd flr). It's 1 main trunk line that goes up to the 3rd floor with branches off on each floor to the rooms. There's no actual "return" air vent. There are however Vents in each room that lead from the room to the hallways. (basically it's a duct that goes nowhere.) Are those considered return vents? The stairwell as I understand it, is the actual return air. The home is designed by the owner of an Heating/AC company and this is his design for a "Green" house. Now can i place my smoke closer to those "vents" (the ones that go from the room to the hallway) in the ceiling then a traditional vent or no? Kind of stumped me today. And since there's a big discussion about the smokes close to the vent, how would one handle the entire stairwell, where I need one at the top of each... I mean... it is a return air vent afterall :)

I think I know what you're talking about. The SD's can be next to those. What you're describing is basically a hole in the wall, w/ a return cover on each side of the wall, right? I've seen that done in remodels where they had no attic space above and didn't want to tear the ceiling out.
 
georgestolz said:
Can you post the whole section?

*sigh* - If i must. Give me a minute. :smile:

Edit:
Here it is; I'm just picking up where your attachment left off. I typed all this while looking at the document and didn't proof read, so if there's a spelling error I'm sorry.

11.8.3.5

(5)
Smoke alarms and smoke detectors shall not be
installed within a 914mm (36 in) horizontal
path from a door to a bathroom containing a shower or tub.

(6) Smoke alarms and smoke detectors shall not be installed within
a 914 mm (36 in.) 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.

(7) Smoke alarms and smoke detectors shall not
be installed within a 914mm (36 in.) horizontal
path from the tip of the blade of a ceiling-suspended
(paddle) fan.

(8) Where stairs lead to other occupied levels,
a smoke alarm or smoke detector shall be located
so that smoke rising in the stiarway
cannot be prevented from reaching the smoke alarm
or smoke detector by an intervening door
or obstruction.
 
Last edited:
iwire said:
That is what I thought as well and how it is enforced by the FDs here, but the language in NFPA 72 does not back that up.
Yes it does NFPA72 ANNEX A pg 72-125 {A.5.7.4.1} Detectors should not be located in a direct airflow or closer than 1m 3ft from an air supply difuser or return air opening. Supply or return sources larger than those commonly found in residential and small cmmertial establishments can require GREATER clearance to smoke detectors. Simmilarly, smoke detectors should be located farther away from HIGH VELOCITY AIR SUPPLIES.
 
brantmacga said:
I think I know what you're talking about. The SD's can be next to those. What you're describing is basically a hole in the wall, w/ a return cover on each side of the wall, right? I've seen that done in remodels where they had no attic space above and didn't want to tear the ceiling out.


Yes, it's bascially just a piece of duct work that's not connected to anything (just helps direct the air from one room to the next I guess).
 
brantmacga said:
*sigh* - If i must. Give me a minute. :smile:

Edit:
Here it is; I'm just picking up where your attachment left off. I typed all this while looking at the document and didn't proof read, so if there's a spelling error I'm sorry.
I sure appreciate it - I figured you had a copy on your computer! :cool::cool:
 
Hold the phone everyone I seem to have stumbled across the confusion reguarding this post. It seems as different sections of the nfpa 72 tell different stories. 5.7.5.3.2 states only supplys and annex A A.5.7.4.1 states supply and return. Cows never give up on the truth. I think a code committee should either adopt one or the other.
 
quogueelectric said:
Hold the phone everyone I seem to have stumbled across the confusion reguarding this post. It seems as different sections of the nfpa 72 tell different stories. 5.7.5.3.2 states only supplys and annex A A.5.7.4.1 states supply and return. Cows never give up on the truth. I think a code committee should either adopt one or the other.

apparently I have never read the annex, but as the code itself is written, it is only required to be 36" from the supply register. I'd like to know what the definite answer is; it seems we don't have one right now, or at least one we agree on. 36" from the supply is the only thing enforced on me. And its worth noting I don't go looking for the returns so I can mount a smoke next to it; all I'm saying is if space gets tight, it'll end up within 36" of the return on my job. I've worked with hallways that are less than 5' long, and there's no way to get it more than 36" away w/o leaving the hallway and putting it around a corner.
 
brantmacga said:
apparently I have never read the annex, but as the code itself is written, it is only required to be 36" from the supply register. I'd like to know what the definite answer is; it seems we don't have one right now, or at least one we agree on. 36" from the supply is the only thing enforced on me. And its worth noting I don't go looking for the returns so I can mount a smoke next to it; all I'm saying is if space gets tight, it'll end up within 36" of the return on my job. I've worked with hallways that are less than 5' long, and there's no way to get it more than 36" away w/o leaving the hallway and putting it around a corner.
Hey I didnt write the code I am just showing you where to find it if you want to follow.
it is not going to be on my license.
I gotta go count some sheep now
 
badabing said:
There's no actual "return" air vent. There are however Vents in each room that lead from the room to the hallways. (basically it's a duct that goes nowhere.) Are those considered return vents?
Yes, transfer vents/ducts is what they are and they just allow air to be balanced by passive airflow.
YesThe stairwell as I understand it, is the actual return air.
Now can i place my smoke closer to those "vents" (the ones that go from the room to the hallway) in the ceiling then a traditional vent or no?
IMHO - yes.
 
quogueelectric said:
Hey I didnt write the code I am just showing you where to find it if you want to follow.
it is not going to be on my license.
I gotta go count some sheep now

Nothing's going to happen to my license; i'm following the code too. ;)
 
Supply and Return HVAC

Supply and Return HVAC

iwire said:
That is what I thought as well and how it is enforced by the FDs here, but the language in NFPA 72 does not back that up.

This is true of commercial/industrial and not applicable to residential. The Supply and CAR scheme are entirely different from factory HVAC layouts.

rbj
 
Status
Not open for further replies.
Top