Motion sensor questions/issues

[ahwman]

I recently installed a motion sensor in a bathroom and it appears to work however not as reliably as I would like. I tried two different positions and a variety of adjustments however I can't seem to perfect it. I first mounted it in the corner of the bathroom right below the ceiling aiming diagonally at the toilet. It triggers when walking in, however if you're in a seated position no motion is detected and the light will go off. I then tried turning the unit upside down to see if that would help and it seemed to get better but yet again if relatively motionless the light would go out. Is there an ideal height to place the sensor?

 

Also, would it be possible to use this motion sensor on a front porch or is it not recommend in an outdoor application?

 

Thanks so much!

[LeeG]

The motion sensor detects the movement of heat, not the existence of heat. If you stand (or sit) motionless the motion sensor will stop "seeing" motion. Note that the red LED goes out very quickly. That does not mean it has timed out and issued an OFF. The red LED only flashes when motion is detected to save battery life.

 

It is not rated for direct outside exposure. Mounted under an eve out of the weather should be okay.

[andyf0]

I don't understand. It's a motion sensor that sends an ON if motion is detected and OFF after a timeout with no motion. If it turns off too soon then you can extend the timeout.

[oberkc]

I don't understand. It's a motion sensor that sends an ON if motion is detected and OFF after a timeout with no motion. If it turns off too soon then you can extend the timeout.

 

Or use an ISY-99 program to control when the light goes out after detection of motion.

[ahwman]

I understand that the timeout can be extended however my concern is that this application will be used in my grandmother's bathroom and at 96 my fear is that if the light times out while she's in the bathroom it could scare her or put her in harms way. If I set the timeout value too long it could also confuse her... Just trying to find the right combination in this situation.

[LeeG]

Do not use the Motion Sensor to turn the light Off. Require the light be turned Off manually as the person exits the room. That is the only way to insure the light stays On. All motion sensors detect motion not the existence of body heat. The lack of physical motion will cause the motion sensor to time out.

[oberkc]

My experience with these motion sensors is that they are NOT precision instruments. They are nice tools, but I would not rely on them in critical applications. It sounds as if your situation may be too critical for these devices.

 

Since you understand the ability to extend the on-times (and only you can determine the proper time), the issue seems to boil down to the reliability of these sensors to detect motion. The only solution that I can think of would be to install muliple motion sensors and create an ISY-99 program to trigger upon any one of the sensor signals.

 

While I am sure that there are better positions within a given room, I don't believe upsidedown will help. I also suspect that any single position within a room will have blind spots.

[Teken]

I would offer to you, for a truly reliable solution would be to use a pressure sensitive media which is placed on the floor.

 

You can Google for them, but note their intended purpose is for hard wired solutions.

 

Teken . . .

[Toddimus]

For what it's worth, I've also experimented with rotating the sensor by 90 degrees when I'm trying to sense motion down a hallway. Since the sensor is normally meant to detect motion that passes side to side in front of the sensor, if you rotate it 90 degrees and tilt it down a bit, it can help sense motion towards/away from it. The idea is that your body parts appear to move across the sensor during your ingress/egress because the apparent angle to the sensor changes. Don't know if my explanation makes sense but it's worth a try. Have a look at the 2420M manual to see the sensing area in front of the sensor to see if rotating might work for you.

 

I've also found that some white electrical tape works well to block out parts of the sensing area to prevent our small dogs from triggering an ON event. This is similar to flipping the sensor upside down, but may be useful in other orientations.

 

Ultimately, I ended up removing the tape, but it did work to mask areas of the sensor if that's what you want to do. Sounds like you want as much sensitivity as possible so its not for your application, but I thought I'd mention it since others might want to try.

 

Cheers,

Todd

[ahwman]

Thanks so much everyone for all of your suggestions. What a great community!

 

After playing around with placement I've started to learn the pattern of detection, however I'm still confused about mounting height. For a small bathroom, what would be the optimal height to mount the motion detector? As I mentioned in an earlier post turning the sensor upside down seemed to do a much better job of detecting motion which tells me the unit was mounted too high. Without putting more unnecessary holes in my wall, I'd love some opinions as to the optimal height for this type of application...

 

Thanks so much!

[Teken]

7-9 feet is the optimum height for most PIR sensors. Keep in mind, you can very well increase the sensitivity on the device to ensure the most coverage is detected.

 

One thing to keep in mind is that you do NOT want to install the motion sensor too close, or in direct ambient light. This will disrupt the sensors ability in detecting moving heat signature of your Mother.

 

In the interim, just use some double sided tape to affix the sensor so you're able to move the motion sensor around with out all the ugly holes left behind.

 

Teken . . .

[LeeG]

If using double sided tape keep in mind some tape was not meant to be removed. Could pull wall paper or paint off. 3M makes all kinds of hangers meant to be removed without damage to the wall including two sided stuff that is meant to be removed by pulling a portion of the adhesive. They have been advertising on national TV the last few weeks being used to keep pictures straight.

[Toddimus]

Good call Lee. I recently pulled a chunk of paint/texture off of the wall when I removed the double sided tape that comes with the motion sensors. At least I think it came with the sensor. I have some of that stuff lying around so I may have used what I had if it didn't come with the sensor. It's some of the really sticky stuff!