BV-500 Motion False Alarms in Summer Months

[dw886]

It seems that over the summer (hot) months, I get false alarms on hard-wired motion detectors (DSC BV-500).  When looking at when they happen, it's always when I've dialed the air conditioning back to about 80 degrees and it's warmer than the AC setpoint outside, so the house actually heats up to this point.  For that reason, I'm thinking that it's heat-related...
 
The PIRs are in high-traffic areas (hallways, etc), and don't have direct view of windows or heating/cooling vents.  False alarms only seem to happen a few times in the summer months when it's hot, and that's how I've come to this conclusion that it's heat-related.
 
After digging into this and reading, it looks like there's a few options:
 1.) Purchase dual tech motion detectors
 2.) Set the BV-500 detection jumper from the factory default of "FAST" to "SLOW"
 3.) Cross zone the PIRs
 
Any thoughts on what is the best approach from a security / reliability standpoint? 
 
If it's option #1, what's the best dual-tech wired motion detector at this point?
 
Thanks!

 

[ano]

Actually this could be spiders. They seem to love motion detectors for some reason and are more active in the summer. (Depending where you live.) So the trick here is to seal them up really good including the hole where the wire comes in. 
 
Then cross zoning is also a good idea.

 

[RAL]

If it's option #1, what's the best dual-tech wired motion detector at this point?

 
The Bosch Blue Line ISC-BDL2-WP12G and 6G are frequently recommended as good dual-tech motion detectors.

 

[Del91574]

The good ol' DSC Bravos. Many problems with DSC detectors over the years (company I was working for at the time used them as their economy device, though all of us tried to get Bosch in-our choice as techs).
 
Cross zoning is a band-aid for a tech that can't fix the problem or a bad system design.
 
Since heat is suspected, first item is to change the pulse count setting (fast/slow) to SLOW.
 
Second, put a small dab of silicone around where the wire passes into the detector to seal out drafts.
 
Third, which many guys have missed before, would be to consider how the wires are running/stapled. I have witnessed cables that metered out fine when the weather or temperature is cool, yet when they heat up, would fault/false. A too-tight staple (say a small T-18 or T-25 from a gun) or a romex staple driven in too tightly would be suspect. The cable(s) should be able to move freely under the staple (with slight resistance if a gun staple was used). If the installer used a flat staple instead of a crowned unit (T-50 or other) then you've got to pull them out or rerun the cable.
 
I had a school that had fire system false alarms during August and only August and only when the ambient air was above a certain temperature and only on a particular loop. 3 other companies couldn't find the problem and shotgunned about $10K worth of parts up to almost replacing the panel itself.
 
Now, all that said, since by the model number, you have ceiling mount PIR's, your options are going to be limited to be aesthetically pleasing. Best I can think of for a ceiling mount  dualtec would be a Visonic Duo 240

 

[dw886]

Thanks everyone.  So the first thing that I did yesterday afternoon was pull the jumpers, changing the detectors from fast to slow (I was reading the manual again, and thought that it was worth a shot - thanks for confirming Del).  I didn't see any spiders when I pulled the covers, but I'll go ahead an silicon them to make sure that nothing can get in, as well as protecting from drafts...
 
The only problem is that I'll probably have to wait a year before it falses again.  It seems like it only happens during the summer when it's hot, and the AC is dialed back for about 36 - 48 hours and the house really has a chance to heat up.  If the AC is running it's normal schedule, this doesn't happen.
 
The wires are stapled with the nylon-shielded staples from a staple gun, and I can pull the wire back and forth, so I don't think that they're crimped.  I've had 3 different motion sensors do this, one on the second floor (cabling in the hot attic),and two on the main floor (cabling between floors in a much cooler space).
 
It looked like there was a "Tri-tech" bosch ceiling mount unit.  Is that one pretty ugly?  I ran across the Visonic Duo 240 yesterday when I was looking for dual-tech options.  Is that a fairly good unit?
 
Thanks!

 

[ano]

Actually I didn't check your model numbers. Spiders should really be a problem for that type of detector, or at least i don't think they are. I was mainly referring to the wall variety.  The spiders get in and walk across the sensor. Its a bit random and rare but it does happen, depending on where you live. (In the southwest, its not uncommon.)
 
If it was me, I'd replace it with a different model, if you can find one, but be careful. Some ceiling detectors are "occupancy detectors" and not "motion detectors."  Occupancy detectors are not for security, but made to operate lighting and temperature controls. They would tend to false alarm more than security sensors.

 

[Del91574]

The only ceiling mount dualtec that you're going to find that is even remotely aesthetically pleasing and not huge is going to be the Visonic. Bosch and the like are about 3-6" tall by about 6-8" round.
 
I'd also toss out checking the terminations in the panel and reterminating. I've also had thermal continuity issues in panels where connections would become intermittent only at a certain time of day. Correlated to when the HVAC was off and the longest time of the day from when it was off. The panel's heat sink would heat up the connections in the panel and the connections would fault, albeit briefly, enough to generate a false alarm.

 

[dw886]

So I've sealed the sensors, and I've set them from fast to slow, and haven't had a false, but that doesn't mean much since this has only been happening about once every 12 months or so.
 
As for the panel, it's pretty much in a bunker.  I have an Elk temperature probe in the room where it sits, and it's never gone over 72 degrees.  The motion sensors on the other hand are all over the house, and the sensors in the upper level can hit 80 if I set back the A/C for those HVAC zones.  Not saying it isn't an issue, but I have far more variance on the far side of the wire - not sure if that would make a difference with terminations or not (at least on the panel end).  Thoughts?
 
I'm thinking if it happens again, I'll start swapping to the visonics...
 
Thanks!

 

[ano]

Not a problem.  You do have to make sure no vent blow on the sensors, and they shouldn't really point at your vents from a close distance, slowly rising or falling temps shouldn't cause a problem. (However the motion detectors do work worse the closer the room temp is to body temp, so keep that in mind.)

 

[Del91574]

Thinking out loud, but if you're talking summer months and falses on the system in areas that aren't conditioned, I'm wondering if the attic heat is traveling through the ductwork and spilling out a register/vent enough to trip the pyro.
 
Just started thinking about it a little more. Wouldn't be blowing air since the system is off, but heat in the ductwork in a 130+ degree attic is definitely going to travel.