smoke alarms going nuts!!!

I had my smole alarms go off this morning at 4:30 AM, all of them approx. 4 simutaneously. No fire and no cause for concern. The alarms went off for about 30 secs stopped and came back on a couple minutes later and again a few minutes after that. Until I got a ladder and disconnected them all. Once off the wall they never went off again(while on battery backup).
This happened a few weeks ago but for only 20 secs then stopped pretty much forgot about it around the same time in the early morning.

The smoke alarms are wired and have 9volt battery backup. I have never heard these go off all at the same time before, didnt know that one tripped the others?? Like most alarms they chirp to let you know the battery needs to be replaced. Also, they are not the kind that detect carbon dioxide.

My first thought was dust buildup it the heating vents? For the most part the vents look fairly clean the return filters are changed often. Is this the heating system the most likely culprit for these to sound off? If so, where to check and what to check on the gas heat pumps? why arnt these alarms going off all the time or different parts of the day when the heat is on?

suggestions?ideas?

Unfortunatly, we had guests staying with us last night

thanks in advance...
Chris

ha- carbon 'monoxide' not dioxide!

Hard to tell what gave you the false alarm...assuming there was not a puff of smoke from somewhere which did it! Ion alarms would not go off from dust, but a photoelectric type might.
The NFPA considers the life expectancy of an alarm unit to be 10 years, as the percent failures to alarm goes up significantly. SO, if you units have some age, just replace all of them.

Are you sure one of your guests was not smoking?

I would replace every five years. If they are older than that, they probably don't work as well as they should. Its really not something you want to chance. As for the heating system, unless the furnace burned up the motor which you would definitely know about (very distinctive smell and lots of smoke), there would be nothing that would set them off. Settling accumulating dust will just render them inoperable or slow to activate which is why its recommended to vacuum them out when you replace the batteries. Construction dust is something else entirely. If you have a carbon monoxide detector, it is probably on the same circuit as the detectors and would set them off too if it was set off.

I would suggest that you replace the detectors. Like I said its really not something you want to chance. Combination (photoelectric and ionization) detectors are the best as they detect both types of fires and alert you as soon as possible. If you don't have a carbon monoxide detector, I'd suggest you get one. Kidde Nighthawks are the one I recommend as they have a digital display that will tell you what the problem is (dead battery, power loss, or actual CO levels).

**I did actually go on one call where there was an issue of some sort of water (condensation or a leak) in the conduit that fed the detectors. It set off the detectors with a trouble alarm. I've seen it once and don't think I'll see it again, but maybe something you'd want to check. If they go off again, count the beeps and pattern. On the back of the detector or in the manual, there will likely be a decoding diagram that will give you an idea what the problem is.