If you took high school chemistry, the answer should be obvious.

CO is somewhat lighter than pure O2 (the ratio of 28/32 but it's not THAT
much lighter. CO2 which "settles" is heavier than O2 by the ratio 44/32.

I have always preferred the digital CO detector. Some perfectly normal
activities will generate enough CO to put the digital models off zero. (In
our case it was cooking on electric stove.) A non-zero reading "for cause"
is a confidence builder: you know it's doing something other that flashing
every 3 minutes.

As far as placement is concerned, a good candidate is "higher up" in the
same room where the CO is most likely originate.

A good location for a second detector is near the bedrooms and, again, high
up.

While I can see why folks are upset that the CO detector didn't seem to do
its job, the more important question is what went wrong to generate 700 ppm
of CO in the first place. CO poisoning cases have happened from time to
time as far back as I can remember. Find the cause of the CO and fix it.


Some years ago an IDIOT of a gas company technician "red tagged" my water
heater because her detector found 44ppm by sticking the probe in the space
between the "funnel" and the actual vent at the top of the gas fired water
heater. (IOW: the actual exhaust didn't have enough CO to cause more
than minor symptoms.)

It takes a serious problem to put 700 ppm of CO into the room air.


"Zephyr" Someguy@an email address.com wrote in message
. ..
Hey folks,

I just finished talking with a co worker who is recovering from a carbon
monoxide scare. she had been sick for the past while and found out
recently
when they checked out her basement and found CO at 700 ppm. She had been
sleeping with the door and window closed and it was making her perpetually
ill. Here's the scary part, she said she had these 1/2 smoke 1/2 CO
alarms in her house. even though the basement was at 700 ppm. (which
according to the specs on my kidde alarm should make it sound in 4
minutes)
none of her alarms sounded. ( I don't know what brand she had)

This made me question my own alarm. I tested it, and it seems to function
correctly.
however, I'm not sure where it should be placed. Reading online some say
that the detectors should be placed on the ceiling, because the CO is
mixed
in with the warm furnace air that rises. However, the person who checked
out my co workers house said that the CO generally falls, and so the
detectors should be lower to the ground.

what do you all think?

This is the alarm I have
http://www.kidde.com/utcfs/ws-384/As...O5%20sheet.pdf


Dave