For some reason at my apartment whenever we sleep with the windows open the carbon monoxide alarms go off. Last night two went off at almost exactly the same time. I can't figure it out. They're only a year old and I can't imagine they're that dirty (some people recommend cleaning them as dust can cause false positives).

The only correlation I can think of is it only happens when it's cold outside and possibly in higher humidity. Last night the apartment got down to ~60 and it had just rained.

Any ideas? I'm getting tired of waking up at 4am with alarms blaring and it's a pain to take them down every time I want to sleep with the windows open.

3/13/2013 10:57:37 AM

You live in an apartment complex or near someone else's house? Maybe a gas heater exhaust vent nearby letting the draft pull the exhaust fumes through the house?

3/13/2013 12:02:32 PM

humidity can cause false alarms, but in a working detector it has to be a lot. i'd look for a vent from a furnace, water heater, fireplace or something.

have you tried replacing the battery or getting a plug-in meter with an LED readout to confirm that its a false alarm?

3/13/2013 12:10:46 PM

Yeah we've replaced the batteries. I haven't tried one with the read out. I'll look for exhaust vents. That's a possibility. I don't think the complex even has gas heaters but possibly for hot water. I'll have to check. Thanks for the ideas!

3/13/2013 12:35:11 PM

How old is the detector? Sometimes they just need to be replaced in spite of replacing the batteries.

3/13/2013 12:50:52 PM

Quote :

"only a year old"

3/13/2013 12:54:30 PM

Particularly after rain, there's a lot of ozone and ionization in the air (you can smell it), which will cause some some detectors to trigger.

I'd wager it's picking up ioniation from outside.

[Edited on March 13, 2013 at 6:53 PM. Reason : ]

3/13/2013 6:51:30 PM

^That makes a lot of sense. It only happens when it's really high humidity after a rain. I'll do some more testing.

3/13/2013 9:01:13 PM