Our recent alarm was a peculiar problem. The alarm was set off by a window that was open at the time that alarm was armed. What I think happened is the following:
- The window was open.
- When my wife armed that alarm, she went through the process to bypass all open sensors. However, for some reason, this particular window did not register with the panel as one of the open sensors, so it was not bypassed.
- About 10 minutes after the alarm was armed, this sensor reported that it was open (even though it was in fact open the entire time) and set off the alarm.
The sensor in question was a mighty mouse sensor: http://suretydiy.com/product/resolution-products-mighty-mouse-re211/
It’s mounted on a vinyl frame window (I have read metal can interfere with this sensor). We have quite a few of these sensors, but this is the first time we have experienced this problem. So far it was an isolated incident so I’m not worried. But I thought I would let you know in case you might have some insight into what went wrong.