Leak detector for AC wall unit

Hi All,

So have an ac unit that requires a small pump to drain the water from the drip tray (long story!) so in the past I had a leak sensor mounted inside the drip tray that would detect water/moisture and turn on the pump. Unfortunatly ive now tried 3 sensors from various brands inc aqara and all work for a while and then end up corroding at the sensors.

Its this type

They were all placed near the top of the water tray but perhaps its the constant moisture they work for a while and then give up completely or become random.

Any ideas of either another more full proof way? Currently i just have HA set to turn on the pump after 30mins of the air conditioning being turned on. And then intervals of a few hours. But its random whether it gets it right. If it fails I get a nice dripping water onto the floor below in the middle of the night usually.

Thanks alot

What is the model of the AC unit in question, someone may be able to help you integrate an ESP based solution to pull the sensors from it and see if it has one for the fill point of the tray.

I understand how they may become corroded, I don’t think their intended purpose is to be submersed so frequently.

You will have to get a float switch, I don’t know any smart float switches, so you will need to add a Zwave or ESP relay to the switch to make it smart. That will last you a very long time.

Yes a float switch like this tied to an ESP setup may be what is needed and to just place it in a way where its consistently activated at the required rate:

You may be able to still use say an aqara leak sensor and just tie the cables to the screw points to act as the remote sensor for it like I do with a pressure mat for a bed sensor with mine.

Perfect! You can get a float switch and connect it to the current sensor!

Its a Daikin , heres what it sees, so maybe the temperature could be a way thanks

ah so i did look at a float switch but the water tray isnt very wide, about 10mm/ 0.4in. so dont think it would fit. And can you just wire that into an existing sensor. Sorry im clueless about this.

You just loosen the screws enough to allow you to hook the ends of the wires into them then tighten them back up:

Then you change the detection mode from leak to something else that more matches when the float sensor is triggered.


Thanks but as i mentioned theres 10mm of room so a float sensor wont fit in the drip tray channel.
Is it just a case of the wires shorting out with the water, can i just leave bare wires in the drip tray?

Find some gold plated wires to solder on there.

What’s wrong with short time based pump cycles. If well tuned, it’s more reliable than chinese sensors. You could adjust the cycle interval based on RH sensor in a room.


They could convert these to fit the role in the thin space to make it work or find similar that allows the state to be registered when the circuit is made.

or even

And you could do the adjustment with the compensation integration.