carbon monoxide detector

I need to get a carbon monoxide detector for a newborn's room. any recommendations as to brand, model, etc? No need for a combo fire/co detector as the fire alarm is part of a system and cannot be replaced. are the led readings of co levels just a gimic? or important for maintaining safe levels? and as to placement, should a co detector go on the ceiling or close to the ground?

I was able to buy a replacement combo unit for a hard wired system. Look at the manufacturer of yours and see if they make one.

Kidde rated highest, First alert rated worst when I purchased mine last year. Mine is a Kidde Nighthawk plug in.

CO is a hair heavier than air implying it should be lower rather than higher but difference is so insignificant it won't make much difference. I know in Massachusetts by law you need CO detectors and they're always installed in the ceilings. I'd say the LED readings are pretty much a gimic and there's just things that fool them easily. Sometimes mine will tell me I reached some number of ppm's at times I've had my boiler shut off for a day and not burning wood, but wasn't enough or long enough to set it off. I've simply started to ignore its LED or peak levels and wait for it to beep before I decide I need to call in the troops. You have to protect them when you're painting, fumes can ruin them and other things. Make sure you read the manual to see when you need to put it in a plastic bag else you risk it being ruined.

My hardwired system is by Firex. This is what and where I got:
http://www.galesburgelectric.com/store/product.php?productid=918&cat=0&page=1

I have had a Kidde nighthawk since 1988. It still works just as well as it ever did. Yes it will show a reading at low PPM. I find that it won't alert till there is a fairly significant amount of Co present but the digital readout still works fine right down to the bottom of the scale. I test it each year with the handy dandy snowmobile in the garage. One nice thing about the unit is that it will show you small amounts of CO long before it becomes a health problem if you just look at it. One other good feature is that it has survived at least 15 rather nasty lightning strikes via the electric system which has fried all of my televisions at least once and ruined a whole host of electronics over the years. That is one darned tough unit.

Actually, CO is about 3% lighter than air. Here's some good reading regarding the position of a CO detector and CO vs. air densities. >LINK<<<

I am happy with my combo Firex smoke/CO detector. It was about $50 at Home Depot. I have mine running on battery, but it can be hardwired as well, with the battery as a backup.