erratic smoke alarms and heat pump connection?

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

They only chirp when the battery is going low, if one is going bad they may go off intermitently until, it goes bad completely, in which case it will stay on.

When properly installed, yes, if one smoke alarm goes off, it triggers the rest to go off. There are two types of smoke alarms generally available: ionization and optical. Each will detect a fire, but they discover them at different stages. An optical one sees big smoke particles. Dust could make it think there was smoke. A slow, smokey fire will trigger these fairly quickly. An ionization detector type looks for the smaller particles created by a hotter, faster fire. These can be fooled by some aerosal sprays. So, there are other things than an actual fire that can trigger them. You need to find out what type they are (they could actually be a mix - i.e., not all the same) before you know what to look for. Also, the fire marshalls recommend replacing all smoke detectors at 10-year intervals to take advantage of newer technology and replace the older circuitry that may no longer be reliable. The test button gives some indication that they work, but not necessarily a complete check.

Another thought...if it was really cold and the auxilliary heat strips in the air handler needed to turn on, they could have had some dust on them and generated some smoke momentarily until that burned off. This time in the season, you'd have probably already had your coldest day and that would have happened, but you never know. If you haven't been good about changing the air filter, you could have gotten some dust on them.