Last night we had two false smoke alarms signaled from the same 3rd floor stairwell sensor. There was definitively no smoke, heat, or other environmental changes in the area.
The sensor is an ESL 12-24V 4W Smoke Detector w/ Heat. It is wired together with a relay (The panel is a DMP XR200L 10-242).
The alarm was professionally installed about 4.5 years ago.
What are the likely causes of such repeat false alarms and how would one go about troubleshooting and verifying them?
What is most likely - faulty sensor? dirty sensor? faulty relay? loose wiring? other?