On Jun 13, 6:45 pm, Nate Nagel wrote:
wrote:
On Tue, 12 Jun 2007 11:40:27 -0700, terry
wrote:

Within the last year or so there were postings here about smoke alarms
that had sounded for apparently no reason. Batteries were good etc.
Somebody mentioned a smoke alarm in close proximity to a shower that
had triggered and we mentioned our own experience a few years ago
where a smoke alarm in the passageway outside bedrooms in my daughters
house had sounded, for no apparent reason, on a warm/humid day.

Recently we finally had what are, for here (North Eastern tip of North
America), a couple of much warmer and humid days. I mean around 78-80
F and sorta sticky! Now I know that's nothing to even mention, having
just come back from the Middle East where it hit +43 Celsius or
approximately 118 Fahrenheit! But around 80 is,-for here, warm;
phew!!!!

I had front door screen open and other windows open letting the
breeze blow through. Suddenly the smoke alarm mounted at the bottom of
our basement stairs started sounding on a regular 30 second to one
minute basis. But this was not how these smoke alarms normally sound
if triggered by smoke. Two other both very ordinary battery models, on
the main floor did not sound.

After a quick check to make sure a pan or kettle had not been left on
and/or overheated on the stove etc. removed the smoke alarm from
above the workshop door way in the basement and brought it up to main
floor. Its been on the kitchen counter for week or so and has been
quiet since! Battery tests good, as it should; only replaced a few
months ago.

Supposition: Some of the seasonally warmer humid air coming in through
front door had drifted down the stairwell, had cooled to the basement
temperature probably around 60 degrees F and thereby acquired an
apparently higher percentage of humidity.

This seems to confirm that some smoke alarms can be triggered by
higher than normal humidity?

Thought I'd post this for information and/or possible discussion.
Terry.

Smoke Detectors DO NOT sound without smoke. It's not possible.
There is a fire somewhere in your house, but its a small fire. You
must find it before it gets big. Get off the computer and go look
NOW. In minutes you may be experiencing an inferno.

Sure they can - at least in commercial applications most smoke detectors
now are photoelectric, which simply measure obscuration. They don't
care whether the light transmission is obscured by smoke, dust, or steam
- if it's x percent obscured, the detector signals an alarm.

I suspect that some (most?) residential detectors may still be
ionization type which have advantages and disadvantages - they respond
quicker to a real fire than photos, but they also contain a small amount
of radioactive material and work well over a narrower range of air
velocities.

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

Tests show photo-detectors respond faster. It is best to have the dual-
type in your home.

I remember, some 40 yrs ago, a door-to-door salesman wanting $250 for
one.(ionization-type) Claiming rodents cause the majority of fires
with their appetite for insulation.
If you gave him 10 leads (and they were sales) we could have one free!
8^)