My experience installing the Aeon Labs Recessed Door Sensor


(Jim Archer) #1

Last night, I installed an Aeon Labs Recessed Door Sensor

This sensor is a two part device, the sensor itself and the magnet. The sensor is a cylinder just under 3/4 inch wide and about 3 inches long. The magnet is similar, but shorter at maybe 3/4 inch. To install, a hole is bored into your doorframe for the sensor and another into your door for the magnet.

The first thing I did was pair it with my ST V2 hub. I opened the sensor as per the instructions, took the circuit board out of the plastic housing and pulled out the plastic tab so the battery could make contact and turn the sensor in. I put the circuit board back in, told my hub to find things and pushed the little button on the sensor. About 7 seconds later ST found it.

You definitely want to pair it before you install it. First, you want to make sure the sensor is not defective. Second, it’s much easier. Finally, you may need to be close to the hub to pair, and it’s a lot easier to bring the sensor to the hub than it is to bring the hub to the sensor.

Installation was relatively easy, and there are a few considerations.

First, I used a 3/4 inch (not 10mm as the instructions said) boring bit. That was fine. 3/4 inch makes for a nice fit. As to it being a wood boring bit, had the doorframe and whatever was behind it been solid wood this would have been the perfect choice. But, after about 1.5 inches I punched through to a void about half an inch wide. That made continuing to bore the hole in proper alignment with the existing hole difficult. I may have been better served by a paddle bit.

Next, the instructions call for a 1mm (0.02 inch) to 5mm (0.2 or 13/64 inches) gap between the sensor and the magnet when the door is closed. That seems easy enough, until you realize that the magnet and the sensor mounting plate do not sit perfectly flush with the door or the door frame. In reality, the gap you need is much wider. My door was installed badly so I had a wide gap near the top, and still it was just barely wide enough.

So, in the case of the magnet consider widening the very top of the 3/4 inch hole just deep enough to recess the magnet. This is easily done with a paddle bit wider than 3/4 inches because the hole you bored will have a center dimple you can use to align the wider bit.

As for sensor, that’s tricky. You could make a rectangular cutout around the mounting hole to recess the mounting plate.

Once your holes are bored just insert the sensor and magnet. The sensor is secured with two small wood screws and, of course, I lost one.

Done with the physical installation!

There has been a lot of discussion about mounting the sensor in a steel door. I suspect that pretty much any door will have a place along the top or side of the frame where the sensor could be mounted, making installation inside the door unnecessary.

Although the sensor seemed to work with the default ST device handler, there is a community provided handler here that I used:

See the discussion in the thread about why this device handler is preferable.

The look of this sensor is much nicer than the sensors that mount above the door and need a magnet on the door, but it’s not completely hidden. There is a red light that glows occasionally to indicate Z-Wave communication and you’ll see that. Not that this is a problem, just wanted to mention it.


#2

Excellent report, thanks! I’m sure this will help a lot of people. :sunglasses:

Steel doors present an additional issue because over time the magnet will magnetize the surrounding metal, and this can confuse the sensor so that it will always show closed even if it is open.

The usual solution is to lift the sensor up off the metal surface somewhat and put a blocking material in between, but this is often not possible with a recessed sensor.


(Alex) #3

@helios - Why did you put the sensor in the frame and the magnet in the door? I installed several and did the opposite with great results. I made a hole with a slightly larger bit as you did on the top of my wooden (well some other material imitating wood) door so that I could drop in the sensor without any friction. Since the door is hollow, I did not have to drill the entire way in which was an added bonus. The hole being slightly larger than the sensor is critical to ensure you can remove it easily to change batteries.I then made a mark on the door frame so I would know where to put the magnet. I drilled a very shallow hole that did not perforate the frame (1/4 inch deep?) and pressed the magnet in so it was flat with he surface of the frame.

Do the instructions say to do it the other way around? If so I totally ignored them and glad I did :slight_smile:


(Jim Archer) #4

I’m glad it worked for you! It may not for others though.

To answer your question, setting aside that the instructions said to mount the sensor in the frame…

As you know Z-Wave is a low power radio mesh system, meaning it’s a network of devices that communicate by relaying messages for each other (very simple explanation). Because they can rely on the mesh and because they are battery powered and because they are unlicensed transmitters, they transmit a fairly weak signal. A solid steel plate will be a nice radio frequency blocker. Wood does not interfere with RF signals. So two steel plates make a nice radio frequency cage.

In may case it probably would have worked fine, as I have other Z-Wave devices in close proximity to the door sensor (although that could change someday). The signal can still escape through the wooden edge of the door. But that could change someday too.

As @JDRoberts pointed out, sometimes a door could become magnetized by the action of a door opening and closing past the magnet if it was mounted in a frame. Witht eh magnet mounted in a door this would not happen, since the metal is not moving relative to the magnet and, even if it did happen, it would not matter as the door is swinging away from the frame mounted sensor anyhow.


#5

You can do it either way. There are two issues to consider:

One) as you mentioned, make sure you can get the sensor out again to change the battery.

Two) because the signal transmit through the sensor piece, you want to make sure that it is not obstructed by the materials around it. And this will be different in different houses as far as whether the door or the wall is most permeable.

If the wall has wire lath, foil wallpaper, or certain kinds of insulation, it may be very difficult to get signal through.

If the door is painted with Chinese red (which has a lot of iron in it) or has certain kinds of foamcore insulation, or obviously is metal, then it may be very hard to get signal through that.

So you just need to evaluate each individual doorway to see whether it’s better to put the signal piece in the wall or in the door.

edited to update

I forgot a third issue: some people are concerned about the effect of the vibration from closing the door on the long-term performance of the radio and sensor in the sensor piece. It can be pretty jarring. The magnet is just a magnet, so there’s not much that can happen to it. But I suspect that’s why most manufacturers recommend putting the sensor piece in the stationary position. But a lot of people use it successfully the other way around as well.


(Alex) #6

Well… I am glad I did not follow the instructions :). My house is made of wood and drywall with very little metal so the dampening of the RF signal is not very strong as possibly in the cases described above. The door is made of some kind of fibrous material (fiber glass?) and in any case all my wall switches are zwave so the distance to the closest node is so minimal I think it would work regardless of the material. As an example, I have an Aeon HEM v2 inside my exterior metal electrical panel and the closest zwave device is likely between 10 and 20ft away but it still communicates just fine. An aspect that is most relevant in this discussion is that zwave uses 908MHz signals so it is less susceptible than Zigbee (2.4GHz) to obstructions.

As for vibration and other things magnetizing, I do not think either are a significant issue in the case of a house door install. I believe the sensor uses a reed contact so I am guessing you actually need a good magnet to trigger its closure and not some ‘slightly magnetized’ material that would likely be way weaker. Maybe a sensor using a more sensitive Hall Effect sensor might have an issue with this but I still have my doubts. Vibration is likely not an issue unless the battery has room to come unseated and break the connection. Usually parts like connectors are the first to fail in high vibration environments but I would not put a door in that category unless you have a cranky teenager operating it :wink:

I’ve had my sensors installed in the doors for over a year without any issues at all.

The one reason I can think of for a manufacturer to suggest installing them in door frames, rather than the door itself, is that it is likely pretty easy to defeat this sensor if installed in a door… all you need to do is hold a magnet where the sensor is located and then open the door holding the magnet in place. If the sensor is embedded into the door frame it will likely take a much stronger magnet to have the same effect. But these are just my speculations… and I do not use these sensors for safety so being able to defeat them is not an issue.


(Jim Archer) #7

Sounds like you’re on top of it :grinning:


(Bruce Robertson) #8

I also put the sensor in the door, not in the frame. Steel on both sides of the door, still paired and works fine. I do have z-wave repeaters nearby though.


(Alex) #9

I believe all plugged-in zwave devices act as repeaters so I am in your same boat given all my wall switches are zwave.

Out of curiosity on why the manufacturer suggests the more complicated install method I emailed and asked them. I will post here what they say.


(Paul Haskins) #10

I’d guess the reason is probably related to the impact a door can have when slammed. No kids, but I have a door from the garage that will often get caught by the wind and get a wind assisted close. It’s often followed by the wife complaining as well.

I have a regular sensor on it and the magnet has fallen off twice. It’s mounted with the 3M type double side tape. Next time it gets the hot melt glue. Did not want to screw it in case I change it.


(Dale C) #11

Nice thorough job on the report. I love this sensor!

I think the instructions for this dimension is the gap between the sensor parts , not the gap of the door. So really all they are saying is you can’t have the sensor parts touching each other so a minimum distance between the plastic sensor parts when the door is closed is 1mm.

And you do bring up a very good point about the gap of the door though. My door has a 4.5mm gap and it fits the sensor in perfectly.


(Jim Archer) #12

Right, exactly my point. You need 1mm for the gap between the parts, plus the parts…


(Alex) #13

I got an answer back from the manufacturer which just said that it really doesn’t matter which side you install the sensor. In my opinion, they should make that more clear in the instructions so that each user can pick what works best for them. @Helios pointed out a few pain points of doing it per their instructions, while it was totally painless for me doing it the other way around.

I’ll share some pictures to show my install in case others prefer to go that route instead.


#14

As a former field tech, I just thought I’d throw in the usual theory and practice caveat…

In theory there usually isn’t much difference between theory and practice, but in practice there usually is.

Which is to say

One) the magnetizing of the surrounding area is a real problem that happens to real people. Not everyone, not all the time, but it happens often enough that there’s an FAQ on it. Any field tech who installs contact sensors knows about this one.

Two) it’s not at all clear that Z wave is better at getting through obstructions than zigbee. You could ask four electrical engineers and get four different answers on this one.

It’s absolutely true that lower frequencies are a more concentrated burst. That’s the theory part. But the practice part has to take into account the device itself and how it is designed to deal with issues like dispersion.

Zigbee uses DSSS. Z wave uses FSK. That alone makes zigbee better at getting through rain even though its raw frequency is more subject to dispersion than Zwave’s. That’s because zigbee was designed knowing that dispersion might be an issue, so the protocol includes some try again countermeasures.

There are a lot of other similar highly technical distinctions between the two protocols. But the end result is that they’re both pretty similar in practice, and the differences of implementation in specific individual devices are going to be much greater than just a general protocol statement, let alone issues of raw frequencies.

If you’d like to see a bunch of electrical engineers arguing over exactly this point, here’s a thread at stack exchange. :wink:

But the short answer is that theoretically one may be superior to the other, but in practice, there’s a lot of engineering that goes into both the protocol and individual devices and you just need to evaluate individual devices individually. :sunglasses:


(Jim Archer) #15

Ya know, the hole for the sensor is the same diameter as the hole for the magnet. If you want, try the sensor in the door and the magnet in the wall. If you have issues, reverse the two. But @aruffell said he does not have a metal door and he clearly understands the tradeoff here.

For people who understand all the issues, install the thing any way you like. If you don’t understand all the issues then go ahead and install it with the sensor in the door frame, absent a compelling reason not to.


(Alex) #16

As promised in a post above I took a few pictures of my install. The door frame is wood and the door itself is some sort of fibrous material. The hole in the frame is very shallow (enough to flush mount the magnet) and tight enough for the magnet to stay in place without glue.

The hole in the door, is just a tiny bit larger than the sensor (I believe I used a different size bit than the instructions said) so that it would be easy to insert/remove the sensor. In one of the pictures you can see that it stays half way out on its own even though there is very little friction to insert/remove. Also, I did not see the need for screws making it even quicker to service.

The magnet is really strong so even though my gap is quite small, I am sure it will work with a larger gap. Before you install you should test it out if your gap is particularly large…


#17

It appears that you have your sensors mounted on the top of the door and jamb. I put them in the side jamb thinking of the carpentry in framing a door…most times there is a header, often a couple of two by eights, framed in at the top of the door. So, I thought there would be less material to penetrate on the side jamb.

I have sensors in 3 doors, all at least 60 feet from the hub, and they have been performing great for a little over a month now.

This was just my thoughts…nothing more.


(Dale C) #18

You missed my point. Your text says the instructions are wrong, “in reality, the gap you need is much wider”. The instructions are absolutely correct because it is referring only to the gap of the parts NOT the door.


#19

How is everyone securing the magnet in the door frame? I followed the instructions and installed the sensor in the door instead of the frame. There is a way to secure the sensor using the included clip secured by screws, but no way to secure the magnet in the door frame. Super glue?


(Alex) #20

If you make the hole of the right size it will stay put just pressing it into place. I do not recall what size bit I used but it did not require any glue and it stays perfectly in place.