Tales of a flawed Aeotec Water Sensor 6 implementation

My house has two HVAC units and the water heater up in the attic. Of course any water leak can cause major damage to the house if not caught immediately. Therefore, I installed water sensors in the emergency pans under the units. On the water heater I used Aeotec’s single water leak sensor and for the HVAC units, I picked the Water Sensor 6 as it can handle two water leak probes.

The other day I was in the attic to finally seal up one of my air handlers, as the company replacing both my coils did a good job on one and an awful job on the other. Maybe an apprentice helping an experienced tech? What annoys me is that I got charged $600 for each coil (just labor) to be replaced so I would expect the same quality work on both. While doing the work, I noticed that the sensor was out of battery (it beeps when you move it) but procrastinated replacing it… bad mistake!!!

The day after I sealed everything up, I noticed plenty of water coming out of the overflow drain for the upstairs HVAC. I raced up to the attic and found the emergency pan about to overflow, with my custom water leak sensor probe floating (literally) in the water! I was so upset with myself for not replacing the battery, or hooking up a 5V supply to the sensor’s dock (all I needed was a wire as I already had a 5V power supply up there!). Some might wonder why the HVAC’s water sensor did not disable the HVAC… well the person who did the awful work on it, had left the pan lifted on the side of the sensor so the water was not triggering the emergency shutoff… and even worse, was making it possible for the water to overflow because the emergency drain was not able to fully drain the pan. Pushing a drain tube slightly to a side allowed me to place the pan back flat.

I believe my shop vac is 12 Gallons, so I must have vacuumed about 5 to 6 gallons of water given it was half full. I live in Texas and it was both super humid and over 42C (108F) in the attic! Not fun to work up there! The cause of the water was condensation leaking into the pan instead of the drain due to a saw cut in my drain pipe!!! The “apprentice” was apparently cutting the drain pipe (necessary to get the coil out of the air handler) and then changed approach and cut the pipe elsewhere. When I sealed the system, I removed the foam insulation that I needed to replace as it was a very sloppy job. In doing so, I must have fully removed whatever was partially sealing the saw cut (the leak was already there which is also why I was sealing up everything given there was lots of condensation drip in the pan). To repair the issue I got creative and sliced off the end of a PVC snap on Tee. I glued it in place with the proper primer and cement. It is a drain so no pressure therefore I expect this fix to last a lifetime.

Saw cut!!:

The part I used to fix it (w/ primer and PVC cement):

The custom probe that was floating in the water (triggers if water touches either of the side screws and the middle screw):


  1. Sensors are useless if the batteries are dead!! Monitor them as things will always seem to happen the moment your battery dies.
  2. Finish the job when you are at it… I have @RBoy 's app to alert me when batteries are low but I guess I did not add the new sensor when I implemented it.
  3. Hard wire when you can… it eliminates the chance you’ll forget to replace the battery!


I finally hardwired the sensor AND replaced its battery given it can act as a backup. A day or two later, the battery was reporting dead at 1%… WTF??? The DTH reports that the sensor is operating DC powered so why would the battery deplete so fast? I know the battery was new and it came from digikey.com so super unlikely that it was a counterfeit (that is why I quit buying them from amazon).

Also, for some reason the sensor is set to constantly beep if the environment is over 40C. My attic is reaching 43C and likely more in the next month or so. Does anyone know of a DTH that can set that parameter (it is configurable)? I am using @Robert_Vandervoort 's DTH as that is what Aeotec linked on their site but it appears to only be a partial implementation.


Sorry for the long read… writing this was my penance for letting my home automation fail me at warning me to what could have turned into big water damage (mold, paint, electrical shorts, etc). Hopefully this will trigger you all to go check your sensors!

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Hey there. I rarely respond on the forums anymore, but thanks for calling me out. I live in Houston so I feel your pain on the heat and humidity. Also, I’ve ALWAYS had bad experiences with A/C contractors. You might get a good tech at first then they send the monkeys to do the work. So much sloppy BS I don’t even know where to start and you don’t want to hear it anyway :slight_smile:

So, having a leak sensor is a GREAT idea. I just replied on my original device handler post as well. Your observations are correct. I need to write a new handler for the modern app and it isn’t completely finished for the old app either but it does work in general.

LET ME SUGGEST, strongly, that you get an overflow float switch. NO A/C INSTALL SHOULD RUN WITHOUT ONE. PERIOD. They cost like $15 and can save you thousands of dollars. If the float comes up sensing water in the MAIN drain line that builds up (which would then start flowing in the emergency line) it closes a circuit (or opens) telling the A/C to shut down. They are compatible with EVERY unit out there. If you have a smarter system like Carrier’s Infinity system there is a specific terminal for it and will display a message and even send you push notifications from the thermostat. If you have an older non-communicating thermostat that just tells the unit to go on heat or cool, then the float switch sits between the cool wire coming from the thermostat and the cool terminal on the unit in the attic or you can put it on the common line as well.

The funny thing is, even WHEN I see these installed, they are usually installed incorrectly! It is the simplest thing in the world to get right but…

Bottom line you NEVER want to see water in a pan. Install the float switches, test them every year and keep those lines clean by flushing with bleach and water or using drain pan tablets which have an algaecide.

Hope this helps man, and apologies the handler is not perfect. I’m hoping to get time to redo it but even in the time it took me to write this, my son has asked me to play with him twice. Tough being an only child especially now. We just had another too and he’s one month old so, I’m not that available these days.

@Robert_Vandervoort - Congratulations on the newborn! I have a 3 and a 4 year old and we’ve all been at home since early March so I know what you are going through. We both work from home and it is tough to tell the kids ‘no I can’t do this or that with you right now’! Hopefully it will get better soon!

I saw the float switch in a few videos but did not know brand and model so thanks for sending me the link! I have two systems that need one! My systems are 6yr old Lennox systems run by 2 ecobee thermostats. No smarts on the HVAC systems… but I can tap into the existing pan sensor (need to see whether both sensors are NC or NO, etc) or just use ST to alert me when the sensor detects water building up. Both HVACs have a zigbee switch each that I can use to power them down.

Looking at the other products from this manufacturer I also saw a transparent trap!

This way it becomes easy to see if there is a blockage in the trap. Since everything is cemented together I will need to buy new traps anyway and the local hardware store doesn’t have U shaped traps like mine.

Where do you suggest I put the tablets? In the trap? That would be the only place I can access where there is water. I do the every 6 month flushing but not with bleach as the plumber said it ruins the plastic over time (and I’ve seen it happen mostly on toilets). He suggested another detergent that I keep in the attic so I don’t have a name for it.

Regarding the handler:

I found where you program the parameter that tells the sensor what to beep for. Since the sensor is in the attic it is almost always above 40C (default limit) so it was beeping all day long. I changed the parameter to beep on everything except temp high since it really doesn’t matter how hot it get up there. That stopped the beeping.

One thing I have not figured out yet is why the battery depleted in a day or two even though the sensor is now powered via the USB port. I still have to replace it to see if it happens again.

If you re-write the handler, could you allow some way to name the probes? For example, I have 2 HVAC systems so being able to name the probes will help me determine which system failed immediately.

I’ve been looking at your code to add options so parameters can be set but your programming is too advanced for me so it will take me a while to understand it. The little I can write is more like very basic C but I was able to add parameters on other DTHs that did not implement all of them. If I find other DTHs written by you that have parameters, I’ll try to copy what you did. If I get anywhere with it, I’ll share back in case it saves you time.

Congrats again on your 1 month old son! Awesome times!