"Phisherman" wrote in message
...
Update...
I read the manual and called the manufacturer. The units that are
showing 10ppm need to be replaced. The tech said to believe the new
unit which reads zero. I've moved the new unit around the house and
next to the others and it always stays at "0" even next to a unit
reading "10."

According to OSHA a CO concentration of up to 50ppm for an 8-hour
period is okay for a healthy individual. A concentration of 200ppm
will cause nausea, headache, fatigue. A concentration of 800ppm will
cause death in 2-3 hours. I know that when CO2 is present there is
also a (much) smaller amount of CO present, both are
colorless/odorless gases.

FYI: Common sources of CO include:
Gas appliances not properly ventilated
Using an oven for heating the house
Using a propane or charcoal grill indoors
Running a gasoline engine in an enclosed or partially-enclosed area
Leaving a house door open to a garage that has a vehicle running

I appreciate all your responses and encourage everyone to have a CO
detector in addition to a smoke detector on all levels of your home.

Amazing what one can learn by RTFM, isn't it?

And yes, it is a good idea to have CO detectors.

BUT, get the ones that have the digital readouts. The other ones that
scream only when the levels are high aren't as good. You might have levels
low enough to give you headaches, but not low enough to set the alarm off.
Or, it goes off after you have gone unconscious.

I have always pushed people towards the digital units.

It's your life. Spend a few extra bucks. A family of four we knew died
after moving a generator into their garage. No one has a clue as to what
they were thinking, but they're just as dead. (Happened in Las Vegas about
a year ago.)

A CO detector, even the cheapo variety would have saved their lives.

Steve