False sensing with 5751 PIR Occupancy Sensor

[tavsec]

I'm noticing the 5751 unit I have on my front patio ceiling seems to be set off by the wind on windy nights - it's fine on still nights

Is the external unit designed to avoid this problem? Is the 5751 not designed for outdoor use, even when well sheltered?

[Forumadmin]

Both will suffer from the same effects. They essentially have the same components. Convection currents can also cause problems with them. Like vents from exhaust fans etc. very hot days can also cause them to not function at all.

The difference between them is one is water/resistant. They have the same specs other than that difference.

Cheers

[coppo1]

"quoted from previous"
>>The difference between them is one is water/resistant. They have the same specs other than that difference.<<

sort of right.....

internals are very similar or near identical... the main difference between the two is the lens design.

external pir has some immunity built into it by the lens. internal unit has no real lens, more like an inert piece of white plastic on the front.

note that when installing internal pirs the cable entry should be sealed as air movement can happen via the cable entry and cause "false triggering".

both versions of pir can be adjusted to some extent, the "debounce" function can be increased to provide some "hysteresis / immunity / deadband", whatever you want to call it.

[Forumadmin]

both versions of pir can be adjusted to some extent, the "debounce" function can be increased to provide some "hysteresis / immunity / deadband", whatever you want to call it.
Been there and adjusted that, Dam its hard to sort out tho. I had one the other week that would just turn on without any help. Turned out to be a return air vent for the "newly" installed AC.
I upped the debounce and so far "fingers crossed" they haven't called back.

[coppo1]

Yep, the 'return air' or "aircond registers" can be a pain. i have seen entire banks of offices false triggering due to:

-poor placement of sensors ( not always able to pick and choose your location)
-poor viewing position ( sensing field) of the sensor, ie facing the corridor.

a good starting figure with your example is 400ms, then i tend to go up from there....

The 5751 internal unit is not a good unit for external purposes, even in weather-protected locations.