Troubleshooting a Swinging Ajax Curtain Sensor Malfunction Event.
Troubleshooting a Swinging Ajax Curtain Sensor – Given the challenges posed by rural applications, the Ajax system we use in the country experiences false alarms occasionally – typically externally with a combination of movement and ambient heat above 36C.
While the Ajax curtain sensor installed outside has occasionally gone into alarm, these events are typically caused by wildlife moving about, so it came as a surprise when the tree-mounted curtain sensor suddenly signalled lid open.
With no camera viewing its location, it was impossible to be certain what the cause of the issue was remotely. By the time I’d thought around the possibilities – given the way the mounting plate and the sensor fit together when closed, these were few – the sensor signalled lid was closed. For the next half hour, the sensor was swinging – lid open, lid closed, lid open, lid closed, lid open, etc.
Because this sensor operates as the first external line of defence in my application, I wasn’t eager to deactivate it entirely, but after a few hours it became obvious these events and notifications were never going to stop, so I disarmed the system and put the sensor into permanent deactivation then rearmed.
It took a week to get up to the country to examine the issue. Of note, this sensor is mounted on a convenient tree covering the 2 primary approaches — to the house on one side and to the lower sheds on the other. Installed 2 years ago, the sensor is partly protected by a timber shroud designed to keep off the worst of the rain and sun.
Walking up to the sensor, it seemed perfectly fine – no significant gaps at the bottom between sensor and plate, which I had expected to be clear to see. My next move was to give the sensor a tap up and down, but the proximity of the top shroud meant a more complicated process was going to be required.
I removed the shroud to the scurry of many insects and knocked the sensor up and out of its mounting plate. Both plate and sensor needed a good scurrifunging. At this point in the proceedings I felt that thermal expansion might have caused some movement and, given the amount of dust and dirt between plate and sensor, a clean might encourage a perfect fit.
However, once I’d cleaned everything off and tidied up the sensing slots, which were dusty and occupied by spiders, I found I couldn’t slide the sensor back into the plate. If one side of the sensor slipped into place, the other side refused to cooperate, and after trying to get it right a couple of times I looked closely at the plate.
Screwed into the tree at 4 points, the plate was twisted, with the lower right-hand side held closely against the tree and the left side further out. Complicating matters, the bark of the tree had grown in such a way as to make it difficult to slip the sensor down into the backing plate channels without catching.
With the lower fixings removed, the sensor base sprang back into shape. My next move was to trim back the bark, so the sensor could slide down into the plate unimpeded. Finally, I went back to the packaging, looking for the bottom grub screw I’d neglected to fit during commissioning. As I screwed this up, I could see the gap between the sensor and backing plate closing as the 2 sections bound together.
Finally, I hopped into the Ajax app to see if my efforts had resolved this self-inflicted swinger issue – they had. The lid was closed. Obviously, if I’m going to use this fast-growing tree as a mounting point – and it really is in the perfect spot – I’m going to need to add a timber mount between trunk and sensor, but that’s a job for another time.
You can read more about the Ajax Outdoor Curtain Sensor here or read more SEN news here.
“Troubleshooting A Swinging Ajax Curtain Sensor Malfunction Event.”
