sensor in my conservatory keeps false alarming?

we have a dual tech sensor in our conservatory which likes to false alarm in the middle of the night ,has anybody else had this problem and how was it cured.The sensor is a Mirage dual technology microwave and infrared detector.
Mr G Corcoran, October 2005


done
I have a good tip for anyone who gets false alarms from PIR's.

I had it for years, and tried everything! It turned out that spideers would get into the hole at the back where the wires entered, especially the one in my living room that goes upstairs into the floorbaords, spiders would walk down the wire and into the back of the sensor.

I blocked the hole with blue tac, no problems since.

Tony, March 2007
Open the sensor, the alarm will start beeping. Put your code in this will silence the alarm and your tamper light will be flashing. Go back to the sensor and turn down the sensitivity or pulse count to 3 and make sure its set for the right height setting by moving the pc board up or down and looking at the scale. Replace the cover on the sensor put your code in and you should be back in the day mode. walk test the sensor if you still get problems get one of E Bay.

Nigel, November 2005
get new sensor

jack, November 2005