Is it my heat sensor that is going off or my smoke alarm?

I have a heat sensor in my kitchen and the two rooms leading off from the kitchen have smoke detectors, one of which is placed very close to the kitchen. Recently the alarms (they are linked) have been going off more frequently than before. This coincides both with an increase in weather temperature and with the breaking of our extractor fan. Do you think it is more likely that this is setting off the heat sensor or the smoke alarms in the adjacent rooms? What could I do to solve this problem?