I have three Nighthawk Carbon Monoxide detectors. One in the
basement, one in the kitchen and one in an upstairs bedroom. The
kitchen and bedroom detectors have been showing "10" for the past 48
hours (the basement reads "0"). There is an attached garage, but
neither car has been running for the past 14 hours. I decided to
turn off the furnace and water heater for a couple hours and open four
windows. There was no change in the readings. I then unplugged them,
plugged them back in, and waited an hour. The readings of "10"
returned. Since there is no combustion I"m wondering where the
detectors are picking up the CO? There are no noticeable odors in the
house, even after being outdoors for 2 to 3 hours. Any ideas?
Keep a window open.
Switch one of the detectors that's reading 10 with the one that's reading 0
and see what happens. If the one that's reading 0 in the basement starts
reading 10 in the kitchen, call the fire department NOW.
Doug Miller (alphageek at milmac dot com)
CO has no odor but with no combustion (that may have an odor) it is hard to
say what the problem is. You fire department will have detectors that can
check things out for you. Better to feel a little silly if nothing is wrong
than to be DEAD right. They won't mind coming out on a service call now
rather than a rescue call at 3 AM.
Better to read the manual, then one wouldn't have
to feel silly.
People in a rational household don't die of CO
poisoning. Those that die are in cars, campers,
motorhomes, and tents doing stupid things without
ventilation, or simply trying to kill themselves,
and people in homes that have done something
extremely stupid like bringing a hibachi into the
living room to stay warm or cook something.
Chronic CO poisoning is a bit different but your
CO detector may be useless for detecting that.
Call your local fire department. They will be happy to come out and
check. They like people who buy and use safety equipment. They really
don't like finding dead bodies. They can check it out for you and offer
suggestions if needed.
Have you read the directions?
On mine, it says that furnaces, fireplaces, and even street traffic can be
detected by these detectors.
A reading of 10 is very low.
Just for the sake of discussion, what is the threshold level? The level at
which you should be concerned? What did it say in the directions?
Once the Nighthawk has a reading, it
holds it as the peak.
It must be manually reset. So, you
really don't know when the
reading of 10 occurred. I might have
been months ago. .
I just went through this. Check your
manual and find out how to
reset .... I don't remember now. The
manual also states what readings
might be ok and the possible causes. If
you don't have the manual,
let me know and I will dig up mine.
"Replace CO Alarms Every 5 Years
Carbon monoxide alarms are valuable lifesaving devices that, when used
and maintained properly, are effective at detecting carbon monoxide in
the home before it reaches lethal levels. Kidde recommends that you
replace your carbon monoxide alarm every 5 years from the date of
manufacture in order to upgrade to more advanced carbon monoxide
sensing technologies and new innovative safety features. All UL-listed
carbon monoxide alarms are required to publish the date of manufacture
on the label accompanying the product (usually on the back of the
alarm). Kidde also recommends testing carbon monoxide alarms monthly to
ensure they are in proper working order and that batteries are still
fresh. It is also important to have home appliances checked annually by
a qualified technician.
Carbon monoxide alarms are designed to activate in accordance with UL
Standard 2034. Individuals with medical problems or those believing
they may be susceptible to lower carbon monoxide levels may consider
purchasing a warning device which alarms at lower levels of carbon
monoxide than those specified by UL Standard 2034. "
so it says at:
That's a very interesting way of putting it. I had always heard that
these detectors have a limited life because of the sensors in them, not
because the manufacturer wanted to sell something new. If it's true
that the existing ones have a limited service life for a valid reason,
you think the manufacturer would have sense enough to just say that,
instead of this BS. I could make that same statement about my furnace
or dishwasher, yet we all know they last a long time.
Read the instruction of the detector to see what "10" means, and what
the instruction recommends you to do. If the instruction says that it
is a dangerous level, trust it and call Fire Department and stay out of
My family (including me) almost died of carbon monoxide because I
didn't trust the detector and spend too much time playing detective
(trying to find out the source of the CO, and trying to see if the
detector was defective or not). I was much better off trusting the
detector and let the Fire Department to figure out what went wrong.
Turned out a squirrel got stuck in the chimney and blocked the vent of
the water heater. My family and I are all fine; but the squirrel of
course was dead, and my ego was not intact either.
a bird caused a similar scare at my neighbor's and they caught it
promptly because they are the worrying kind. i guess we just buy these
alarm devices and think we are smarter than they are. thanks for your
chilling and informative post.
"Chilly" is the right way to describe it. I have the exact feeling
when I think about this.
My relative was with my two kids in the basement (I was wasting time
playing detective at that time, and I told them it had to be a false
alarm and I changed the detector, not to worry..., and then I went to
work). She felt a slight headache, and had a feeling of wanting to lie
down to sleep. Good thing she didn't! Instead, she and the kids went
upstair and slept in her room upstair. Otherwise, I would have three
dead bodies in the basement, and I would blame myself for the rest of
I really hope that the person who started this thread will check the
manual and see what "10" means and follow the suggestion in the manual
to the letters.
I have a Nighthawk, and it drifts up to about 7 or 8 occasionally
(sometimes 9) for no apparent reason. Even with the windows open.
Resetting it doesn't help. Eventually, it settles back down to zero.
The detector works great when there actually is a CO problem (trying to
light a cold wood stove, or one big smoldering ember in the stove which
then start backdrafting.) I think it just loses it's zero calibration.
10 is a high enough reading to almost start being a little concerned.
Almost. HTH :-)
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