Smoke detectors and Ceiling fans

[skeshesh]

The smoke detector's sensitivity to false alarms depends on the product as well. There are many products on the market that have more than one sensing technology with pratically eliminates false alarms. I had a contractor show me a janitors closet in an installation where he kept the hot water for mopsink, etc. running for a couple of minutes with the smoke detector installed - no alarm. When he opened the door the room was full of steam. I let them keep them in in those closets since there will likely not be a situation like that frequently to damage the alarm. This type of product is also useful for kitchens etc.
The other issue is the moisture which comes into play in shower areas and such. Smoke detectors are generally not rated for operation in a wet area or areas where excessive moisture is present. In such cases use of a heat detecter is appropriate.

[ptonsparky]

We pretty much center ours on the door into the room about 16-18" from the wall. Some small bedrooms with fans just don't leave much room.

Note: Placement really has nothing to do with the NEC unless you consider installation instructions.

[Dennis Alwon]

If I remember correctly, the wording of the code is "forced air supply"; I do not interpret that to include returns also.

It definitely includes return air grills.

[Dennis Alwon]

Also, with the ionization type dectectors, burnt toast or bacon will set them off. That's why NFPA 72 requires they be installed no closer than 20' to a cooking appliance unless equipped with a silencing feature.

Are you sure it is 20'. I did a house where it would be impossible to be further than 20' from a kitchen and still be near the bedroom area. I rarely install them anymore as they are usually part of the low voltage system.

[brantmacga]

It definitely includes return air grills.

explain.


"supply" and "return" are two completely different things.

i am not in agreement with you.

[brantmacga]

Are you sure it is 20'. . . .

i thought it was 12'; but i don't have a code book in front of me to check.

[Dennis Alwon]

explain.


"supply" and "return" are two completely different things.

i am not in agreement with you.

Well let me say this-- you won't pass around here...:grin:

[brantmacga]

Well let me say this-- you won't pass around here...:grin:

i may come up there and do some work just to have this argument.

i've had one inspector call me out on it; i told him find a dictionary and get back to me. job passed.

anyhow, like i said, if their intent was to include returns, then it should be worded as such.

until then, i won't be convinced otherwise.

i suppose one could say the return is "supplying" a forced air system; i'm not buying it though.

[jsharvey]

i may come up there and do some work just to have this argument.

i've had one inspector call me out on it; i told him find a dictionary and get back to me. job passed.

anyhow, like i said, if their intent was to include returns, then it should be worded as such.

until then, i won't be convinced otherwise.

i suppose one could say the return is "supplying" a forced air system; i'm not buying it though.

This may be just around here but the Fire Marshall explained it in a class many years ago that the distance was because of the air movement involved with a forced air HVAC unit. To close to the supply and and it blows the smoke away from the detector, to close to the return it can suck the smoke into the unit before setting off the alarm. Either way it would take more smoke build up to activate the detector than if it was away from the vents.

[construct]

Are you sure it is 20'. I did a house where it would be impossible to be further than 20' from a kitchen and still be near the bedroom area. I rarely install them anymore as they are usually part of the low voltage system.

Sorry for the delay in replying Dennis. I am not always able to visit the forum on a daily basis.
Actually, I was incorrect. NFPA 72 Sec 11.8.3.5 (4): Smoke alarms and smoke detectors installed within a 20 ft horizontal path of a cooking appliance shall be equipped with an alarm-silencing means or be of the photoelectric type.

Also Sec 11.8.3.5 (6): Smoke alarms and smoke detectors shall not be installed within a 36" horizontal path from supply registers of a forced air heating or cooling system and shall be installed outside of the direct airflow from those registers.