Intrusion Alarm Motion Detection Issue

Quick question,

I took over an intrusion alarm account/system and am having issues with a wired zone on a vista 128 (4 years old). Every once in a while when armed and no one in the building, a motion detector will trip and the system alarm. The motion detector is in an open, cubicle space with no facing windows, except a glass door approximately 35-40ft away.

Steps I've taken so far:

- Replaced the motion device

- Checked the cable for continuity

- Reprogrammed the zone (idk, just tried)

I typically use glass breaks instead because of reasons like this so I honestly know very little about motion; like what possible items could be setting it off. Here is the spec sheet of the motion detector.

Could anyone give me suggestions of environmental issues to look for? Could it be the panel contacts on the zone? Any suggestions are appreciated, thank you


I'd guess it's HVAC related. Heat or A/C coming on at times and tripping the sensor.

In offices I've also seen problems with mice at night setting off ceiling motions.

I've used an older version of that sensor as an occupancy sensor in home automation setups. The nice thing about them at the time was the fact that they were pretty sensitive, but that could be a downside in your application.

Have you tried adjusting the sensitivity of the sensor at all?

Those make great rodent detectors that run along walls and edges.

That spec sheet shows two options. A single and duo. Which one is installed?

Much like analytics there is a balance between detection sensitivity and false alarms.

Try increasing the "pulse count" if available. It requires more detections before triggering an output.

if it's the Duo, the microwave isn't temperature sensitive but can see things you don't like water in a plastic drain pipe!

That panel might also have a "pulse count" option in programming. That would reduce both the likelihood of false alarms and detection.

You could use a different brand that isn't also designed to be an occupancy sensor.

As Brian mentions, the HVAC is always an issue that goes overlooked. If the motion is anywhere near an HVAC outlet, the hot forced air will set off a PIR. Just as common are spider webs on the face of the motion, spiders inside on the lens of the motion. You cannot see them, but they are there and when they move around they set it off. Also be watchful for things like balloons or anything that might be hanging or floating in the space (ceiling fans and the like). That too is motion. I have motions in my den, and in the summer it heats up in there if the fans are on, we get alarms.

You could also have a bad motion or a bad zone, but more likely motion. You can switch the motion to an empty zone and see if the problem follows, or put a motion that you never have a problem with on that zone and see if the zone still has issues.

I prefer DualTec motions as mentioned. It takes heat and motion to set them off. They are not immune to false alarms, but far less susceptible.

My last thought is are you positive that that no one (man nor beast) is in the room?

Is this zone on the panel or on an expansion module? Is the detector on a hard ceiling or drop tile?

As asked above what did you set the pulse count at? I've used a lot of that brand of detectors and never had issues with insect penetration or device reliability.

I'd make sure the ceiling is rigid and immune to air pressure waves causing the tile to jump -does it line up with extra windy nights? I'd also check the solder joint under the terminal to see if some over zealous tightening had cracked the pin to trace solder joint.

Is the PIR set to trigger on a single event or is it set for two? If it's set to 1, setting it to 2 might be helpful in reducing FAs...

I no longer use ceiling mount PIR's that face down due to this problem. I have plenty, new in the box, that I'll never use. There are too many things that can make them trip. Rodents on the floor are a problem with these types of detectors, even if you use multiple pulse counts. Some people have had luck with them, but I stopped using them a long time ago. I've not seen a ceiling mount detector with pet immunity. Unless there is a floor heater in the detector's view, or an air vent really close to the detector, I think it's seeing rodents. Also, check for insect infiltration and seal up the detector's wire penetration with silicone. As others have pointed out, hanging decorations, balloons, etc., can trigger them too. Air conditioners cycling on can cause vibrations and trigger motion detectors too.

A good PIR with pet immunity and some careful placement could solve this. I seldom use PIR/MIC now.

Is this detector in the middle of the room? Can you change it out to a pet immune detector that uses a ceiling bracket? This way you get pet immunity which should ignore the rodents and you may not need to relocate the detector.

My approach would be:

1. Replace the detector with a different type that incorporates pet immunity.

2. Relocate the detector to a corner looking inward, avoid having the detector looking outward or at windows, especially sunrise or sunset, and car headlights. Use a ceiling bracket if you must.

3. If the detector has 1,2, 3 pulse counts, use 2 or 3.

4. Bosch makes some good motion detectors. I use Honeywell too, but when I have tough environments I use Bosch. I think Detection Systems is now Bosch.

I think glass break sensors should always be backed up with motion detectors in commercial settings. Residential is a different situation, especially with dogs and cats. I don't think glass break sensors are as reliable as motion detectors for detecting intrusion.

I agree with this, especially considering that intrusion seldom requires breaking glass. Modern pre-hung door unit frames have terrible kick resistance, and a forceful boot or prybar can often open one with modest effort.

Even commercial frames can be bent free of latchbolts in many cases. 20 gauge steel just isn't that tough.

Why bother busting a window?

Those motions often cause false alarms; you should use Bosch pro series motions. Much less prone to false alarm issues. We have installed thousands of bosch pro series and have almost no equipment related false alarms.

As brian said, you should check the HVAC vents and see if they're sending warm air into the space.