the smoke detector alarm goes off but its not because of smoke. What could be the other probable reasons? Is condensation a probability? Is getting a central humidifier going to solve the problem? What would be a good route to take?

I had this problem last year... have you changed the batteries recently?

Is it a photoelectric or ionization type?

How old is the alarm? They do go bad regardless of how well they are cleaned and maintained..

I had a problem with a central system at a hotel I worked for(Imagine that in a full scale hotel,, ugggh)

We found spiders in the individual smoke detectors, as well as dust etc,as pelle stated maintenance (compressed air used to clean computer keyboards) and as J-9 said, battery changes do a lot for the protection and proper operation of the systems.

Ken

Go back and answer the question KISS posed. Is this smoke only or is it also a carbon monoxide detector too?

Rather than wait for an answer you may not have, some ''smoke'' detectors also or really detect the ions given off by combustion. The heat exchanger in your furnace could be allowing not only ions, but CO to leak into your house. This is a serious problem. I would take a good look at your furnace and maybe invite a professional to have a look.