We have a ventless heater in the living room for those times we have a cold north wind (it's an old farm house). So I put a FirstAlert Co detector in the living room.

 

It seems to randomly beeps and says "TESTING! co2 detected. co2 levels of 0 ppm" A bit annoying, to say the least.

A little Googling and I find we aren't alone. I found a discussion onine at http://ths.gardenweb.com/forums/load/wiring/msg111948236128.html  It seems the FirstAlert SC07 can be tested by pointing an infrared remote control at it. And others have found that CFL bulbs and flat screen TV's can set them off.

I moved the CO detector to another room and will have to go shopping for one for the living room. Hopefully that cannot be tested by a TV remote control.