Hey all,
I’m looking for suggestions on how to monitor a partially open window. We like to sleep with our bedroom window slightly cracked and would like to monitor our window so we’ll receive an alert if the window is open past a certain point.
I thought about placing the sensor so it reads closed at the halfway open point, but then closing the window would result in a notification.
Any suggestions?
What type of window is it exactly?
A lot of people just treat these like patio doors and put A bar or a lock that keeps the window from opening past a certain point.
After that, you have a couple of options, but it depends on exactly the layout of the window. You can put a tilt sensor on the bar. Since the bar has to be moved to open the window further, you get an alert from the tilt sensor which you then react to based on mode and security arm status.
Of course this doesn’t help you if someone just breaks the window, but then your open/close sensor doesn’t help you with that either. 
There are some bounce beam sensors that can trigger if something moves too far in one direction, but again, it depends on the exact design of the window.
Sometimes a curtain motion sensor can catch the motion of a window as it comes in one direction although to be honest it’s more likely to catch the motion of a person’s arm opening the window. These work in some set ups but as I’ve posted before I don’t like motion sensors put right against windows. You get too many false alarms from temperature variations.
I’m sure there are other options, those are just the ones that occur off the top of my head. A tilt sensor on a blocking bar is going to be very simple and can be easily integrated with SmartThings. But it won’t fit all window set ups.
( by the way, I’m assuming that this is a window that you often open all the way during the day when you’re home, and that’s why you don’t want to install a window stop. But just in case someone finds this in the future, Amazon does have a whole category for window locks and stops. you’ll often find these locally in the baby proofing section. They don’t issue a report themselves, though.)
Assuming this is for a double-hung or sliding window and you don’t mind if the sensor reports as closed when in the partially open position, you could put the electronic portion of the sensor on the part that moves and magnets at the closed and partially open positions.
Don’t know if they exist, but if there are sensors that can report the strength of the magnetic connection you could use different strength magnets to distinguish between the “closed” positions.
@Keo - I use another magnet for the partially open position (as @dama mentioned). I had a spare from a broken sensor.
Haven’t been able to find decent extra “replacement” white one to put on the other windows though.
Any strong magnet on its own should do. I took apart the magnet side of Quirky Trippers for a couple of my installations. You could paint the magnet white or even embed it in the frame if you wanted to completely hide it. In the second photo the magnet is tucked into the insulation strip around the door.
Do you need immediate notification? If not, there are notification SmartApps that have a delay factor for the first notification, so it could send a notification if the sensor has been open for more than 1 minute.
Do you need notification while you’re home? If not, and you have presence detection set up and use Home/Away modes you could only have notifications sent when mode is Away.
Could you do two sensors (one in full closed position the other set at partial) and not trigger unless both are open for x minutes?
I thought about this, but it is essentially doubling the cost to monitor a single window.
There is this. Option I guess. Are there vibration sensors that work for smartThings? Maybe instead of a contact sensor I can sense vibration. Would the window moving be enough to trigger a vibration?
There are several brands of Vibration sensors including the smartthings multi, but they all cost about twice that of a contact sensor. ( these are what people use to detect knocks on the door or a dryer going off.). They are also pretty sensitive, and would indeed probably alert when the window moved. That might work for you or it might not. That’s why I thought of the tilt sensor instead, because it won’t alert when you are closing the window, only if you lift out the bar.
As @dama and @zatman have already suggested, you can use one sensor and two magnets so that you are moving the window from closed position A (fully closed) to closed position B (partially open) so long as you have a delay on the alert of a minute or so. However much time it takes you to move the window from position A to position B, or back again. Magnets are cheap. 
This is why the exact design of the window matters. Not all solutions work with all types of windows.
The 2 magnet/1 sensor solution also requires that you be able to position the partially open window in exactly the right spot each time to set the sensor closed again. Sometimes that’s easy, sometimes it’s not, especially in the middle the night when you’re hot and you wanted to adjust the window.
If you use a removable stopper instead, you won’t physically be able to move the window too far even if you’re half asleep.
So as always, just comes down to your specific needs for this use case.
Here’s my thought. If you’re not the one moving the window, you are probably about to experience a problem.
Put the sensor on the window sash. Put a magnet to measure the closed position and one to measure the partially open position.
This will make the sensor read closed in either position.
Set up a rule to alert you when the window becomes open. You can set it to work only in certain modes our at certain hours.
