Harsh Environment PIR/Microwave Detector


Senior Member
Can someone recommend a harsh environment (attic space could get very hot) PIR/Microwave combo detector?
An attic space can be brutal on electronic gear because of the high and low temperature extremes. Insect infiltration can be a problem too. In the old days I have laced wire across the plywood to detect cutting through the roof in gambling establishments. That may still be a viable way to do it. A newer and more high tech method could be to use flex sensors on the joists in the attic. Check out http://www.sureaction.com for info on these. I use these in historic homes and museums if a visible device is out of the question. I have never had a false alarm from one of these. Just follow the instructions and don't hesitate to call the factory if you have any questions.

Good luck!
I have one PIR/Microwave that have not installed yet. What I like about them is that they cover a large area, and most let you calibrate the microwave range sensitiviy.

I like the SureAction Pulsors for floors, stairs and beds (automation), but I think that they dont cover a large area, so burglar must step on the area of sensitivity (a a few feet from the sensors) in order to detect.

Gizzmo - Have you used the Pulsors in attic space? I wonder if the temperature variations could cause bending of the joist pillars and thus, cause a false allarm.
initial thoughts would have led me to agreed with gizzmo, but then I was thinking I have an air handler in the attic (A/C only) and the electronics in there have had no issues for the 7+ years it's been installed . .

and you gotta think a warehouse can have similar conditions (heat/cold/bird,bat,squirrel or other misc rodent) . .

if you hunt around you can probably find something . .

Pete C
pete said:
if you hunt around you can probably find something . .
I have my distributor looking into it. I might just put one up there and stress it to the max until it fails. Or, set a custom rule that bypasses the zone when the temperature reaches a certain limit.
When installing any Microwave/IR type motion detectors in attics or warehouses be sure there are not rotating objects, fans or ventilators as they will trigger the micro part of the detector. Also, if the attic is not heated(which most are) then there is a chance of thermal ghosts around air leakages from the heated part of the area.

Many of the detectors don't function above about 90 deg F. This is due to the small difference in thermal temperature in the area. So they don't detect anything.

All of the above will tend to create false trips. A better solution would be to analyze
the area carefully and see what is really needed for security. Consider where access can be made and then decide how to protect it. Just a small wire that can easily be broken is very dependable to protect access(screens are just one that comes to mind).

On small metal buildings that you can cut into easily can be protected by running
a thin wire around the walls about 2 to 3 ft. above the floor.

Cliff s
Last year here on Long Island there was a group of burglars that would cut through the roof, go into the attic, and then kick their way through the sheetrock to access the second floor of the house.

They did pretty well for a couple of months until the apparently made some mistake and if I remember correctly someone was home and contacted the police who picked them up in the neighborhood a few minutes later.

I just put a couple of motions on my upper level since the only thing of value in my attic is the christmas decorations (which we have to many of anyway :angry: )
Here's what my supplier came up with:

Bosch OD850. The operating range is -40 to +130 degrees Fahrenheit. I think that will do the trick. Thanks for all the replies.
rfdesq said:
Here's what my supplier came up with:

Bosch OD850. The operating range is -40 to +130 degrees Fahrenheit. I think that will do the trick. Thanks for all the replies.
Don't know where you're located, but in SW Missouri my attic gets ovr 130 degrees in the summer :angry:
A Crow D&D sensor I have had in my attic for about a year now.

Operating temperature range is -4 to 158F. I don't recall any false triggers, but it is not hooked to the alarm system. I put it in because i never remember to turn off the light.

Where were you a week ago :unsure: ? I have an email into my distributor to see if they can get me the Crow D&D. Thanks.

Edit: I was able to cancel my Bosch order. The Crow D&D spec sheet reads that the PIR only goes to 122 degrees Fahrenheit. I called tech support, pretty snotty, and he confirmed that there was a typo in the spec sheet and it does go to 158 degrees. I'm going to give it a try.