Motion sensor seeing ghosts

I'm thinking my house is haunted. Seriously I cannot figure out what keeps triggering my mail slot motion sensor. I thought it was such a clever use of a motion sensor. Mail slides down the slot, Hubitat through echo speaks tells me I've got mail. At first I thought it was seeing some curtains moving when the heat comes on, but I taped up the sensor a bit to narrow its field of view. Attached is a Pic. Any thoughts?

My other thoughts were to use a contact sensor on the flap outside or an aqara tilt sensor, but anything inside of the slot is subject to being torn out if too much mail is jammed in at once.

Just a thought, but given that the slot is exposed to outside air, you could be getting a slight gust through that has just enough temperature difference to set it off.


As entertaining as the haunted house option may be.... including mail for previous (current) occupants....

There have been some quite extensive topics around this before, from memory, mostly delving into then technical aspects of the sensors used. I'd suggest searching more for those threads...

Indeed. My side gate motion sensor also sees my dryer vent. On cold days, the temperature differential of the exhaust was enough to set off the motion detector.

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I did not know that was a thing. Had no idea that a temperature differential could set off a motion sensor!

I was going to suggest bugs or moths or something like that, but maybe you've already ruled that out?


I have a Ghost too but it is what it is somtimes :slight_smile: When I walk by my office the lights will come on sometimes even though the sensor is around the corner and in the bookcase.
My passing heat bounces off the adjacent office wall and triggers the sensor.
You set up a trip wire and a magnet to a contact sensor.
Rube Goldberg all the way, enjoy the journey!

I have my sensor underneath the mailbox and have it report acceleration. Works great until some redneck (no offense) drives by with loud mufflers. Sets it off every time.

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Your SONOFF is a PIR sensor ("A passive infrared sensor is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view.")

IRC my bosch motion sensors advised against pointing them at windows and doors due sunlight causing false triggering. Forced air heating could also cause false triggers.

What about a contact sensor with the magnet mounted to a lever that is hinged?

Why not use a tilt sensor on the flap? NYCE makes a zigbee sensor, and Ecolink makes a zwave one.

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Yea I think I'll have to do that. No matter where I put the motion sensor it keeps seeing the cold or whatever it is.

On a side note is their such a thing as motion sensor that doesn't track heat?

No, motion sensors work by sensing infrared radiation, i.e. heat.

Do a search on microwave or radar motion sensors; you should find a few mainly geared toward the Arduino platform; don't recall ever seeing a zigbee or zwave one.

Your post reminded me that @iharyadi had made one a few years ago. Don't know if he still uses it.

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