Have you cleaned them? At times our smoke detectors have activated because a spider or some small insect found it's way inside. Dust can also be culprit. I now regularly vacuum all the detectors.

Hard wired units may also have a battery back-up that needs to be changed.

Although it's only a couple of years old, it may need to be replaced. We needed to replace 7 year old detectors a few years ago. Some do have an expiration date.

It could also be placed incorrectly. I wonder about how close it is to your stove?

Buy a couple of standalone battery-operated units from HD or Lowes for confirmation.

If they all go off, then you know for sure you have a problem.

It's a very serious issue. I'm not sure I'd be staying in the house (or at least not without a couple windows open all the time) until it's figured out.

Does your range run on propane or natural gas? Did it come from the factory set up for the correct fuel type or did it have to be converted on site? Who did the installation? Is the flame blue? Do you use external ventilation when cooking? How tight is your home? It's possible that even with external ventilation that your home is so tight that unless you have makeup air, your range vent cannot exhaust.

Thanks for all your comments.Rrah,the fire department looked over the alarms carefully and the batteries are all new but I suppose it is possible that they could be worn out. I had hoped they would last longer than 2 years but i will look into it.

Chiefneil a tandem alarm is an excellent idea and would give me peace of mind if nothing else.

Green Design...these are very good questions and I can't answer all of them. Here is what I can answer. I have natural gas, I have external ventilation but was not using it in any of the above mentioned incidents and yes , my house is very tight.Should I always be using a fan when cooking with the range. I usually only use it when there is smoke, odors or I am frying some thing with a high flame.I will try to find answers to the other questions. If the problem is the range should I be calling the person who did the install or the manufacturers recommended service?

Are all the detectors the same brand? I ask only because a neighbor had an addition put on and had new detectors connected up to the existing set. They got a lot of false positives, too (including at 3am, which was super annoying). They finally made the builder swap them out for the same brand as what was in the rest of the house and the errors stopped. They think that the "universal communication protocol" between all the units wasn't quite universal after all and the new ones either 'said' or 'heard' something that triggered all of them to go off.

That was the super frustrating piece for her, she couldn't tell which one thought it saw smoke because they all go off together.

Just a thought, I hope it gets settled out quickly. Those things are SO annoying when they don't work right.

Thanks EngineerChic...they are all the same brand and you're right it is very frustrating. I think the worst thing for us to do is assume the problem is the alarm and ignore a more dangerous problem. To have an extra alarm as a back up test may help us with ruling out the detector as the problem.

I forgot to mention that some friends had been having headaches for a few weeks before realizing they had a CO problem. They didn't have CO detectors.

Of course you don't want to rely on headaches as an indicator of a problem since you could just as easily pass out with very unpleasant consequences, but it's something to watch for.

"I had hoped they would last longer than 2 years but i will look into it. "

Not likely unless they are lithium.

Typical dry cell batteries have a shelf life, even without an outside load.

Duracell marks theirs, but many others do not.

If the units use conventional 9 volt batteries just replace them every year.

There is NOT a charging circuit in the device, since most conventional dry cell batteries are NOT designed to be recharged.

Brickeye..... Our system is hardwired and the back up battery system has all new batteries. I was questioning a useful life of only two years for the alarm system.

Chiefneil, the fire dept did run down the list of symptoms related to co poisoning. We have been experiencing many of them but we are in the fifty something age category so headaches and fatigue are an every day part of life :)

Thanks everyone,this has been a helpful discussion. I have made an appointment to have a technician check out our range and in the meantime we will set up a tandem alarm system to see if we rule out am alarm malfunction. I will let you know what we learn.