Detecting if my attic fans are on or off

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25

These "bacon sensors" are extremely sensitive and will probably trigger from vibration on the frame when the fan is running.

Aqara Vibration Sensor, REQUIRES AQARA HUB, Zigbee Connection, Wireless Mini Glass Break Detector for Alarm System and Smart Home Automation, Compatible with Apple HomeKit, Works With IFTTT Amazon.com

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Another potentially simple option would be if the fans have duct work that has louver that open when the fan is on to allow it to run simply attach a door sensor to them.

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27

Fans kind of vibrate while they are going, is there anything (battery controlled?) that can detect a kind of humming vibration? To eliminate false incidental bangs and clatters you can use "and stays that way" in a rule.

Or maybe a little camera or microphone so you can see what's going on by looking and listening. Thats what we ended up having to use to check if our dehumidifier needed emptying.

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28

That's good too.. but I kinda like the idea of detecting the current in the wiring. Seems like less potential for false positives.

With a split current switch like @aaiyar uses it seems relatively trivial to install - and given the EcoLink has built in terminals internally no soldering or anything required.

You would have to buy 2 devices though... and I would probably hardwire the Ecolink so I would not have to replace the batteries.

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29

Yup, it is a direct test of whether the fan is drawing power or not. And while the initial outlay does require two devices, as you state, the reliability and accuracy are excellent. Never had a miss!

Exactly what I do for this application - my HVAC/Sonos GoControl contact sensor is hard wired. It is basically underneath the air-handler, and hardwiring it ensured I wouldn't have to contort my (aging) back to replace batteries :joy:

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30

In my experience, they were insufficient to detect when my dryer was running. Here's what would happen:

  • The sensor would trigger when the dryer started.
  • But then would stop detecting vibration while the dryer was continuously on.

So when the dryer actually ended, there was no event to indicated it had ended. Others got around that by mounting the sensor on a coil spring and attaching it to the dryer or washer.

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31

I would expect if you can do it both would probably be good. As much as you want to know if the fans are running: you probably also would like to know if you have a direct opening to the outside when you shouldn't.

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Out of curiosity what is controlling the fans now. You indicated they are controled by humidity and temperature so they do have some smarts to them.

Are they home exhast fans, or simply for atic circulation of air? Is the humidity reading from with your home, simply about your attic, or does it do some kind of check of inside and outside? If they are exhast fans do you try to open the windows when it is running to help it cycle air through the house better?

33

Try something like this:

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34

They are hardwired roof fans that blow air out of an insulated attic. The roof also has a few vents to allow air to enter attic when fans turn on. Each fan has an integrated temperature and humidity sensor, and I can set what temperature or humidity they should turn on.

All you guys have come up will some great ideas. Iā€™m really liking the Current Relay and Contact Sensor idea! Iā€™m not much of a hardware guy, so tell me if I understand this.

I run a wire from each of the two terminals on the Current Sensor into a battery powered Ecolink contact sensor. No other power source required. Run the hot wire going to the fan through the Current Sensor loop. Pair the contact sensor to Hubitat and bingo, it will work?

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35

Correct. I would suggest making sure you get a CT that can detect the amps in the range drawn by your fan. There are ones available that can do 0.1-100A that would be perfect.

Also, I really like current sensors made by Functional Devices here in the US. They just last forever. This split core sensor will be perfect:

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36

This is my favorite in the "cheap and easy" category. Nicely thought of.

However, monitoring the current seems like the way to go as it seems 100% reliable and since the item being monitored is out of sight, being sure of the status is important.

And as a big plus, @aaiyar offers one year of free phone support! :wink:

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37

@daleberlin - I would be careful about using battery powered devices in your attic especially if it gets really hot. Consider hard-wiring the battery terminals.

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38

@daleberlin - this is a good idea. But why don't you get it working first, and then you can redo the battery on the Ecolink sensor.

Also, you can pass the hot or the neutral through the current transducer. Just not both.

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39

Just noticed this and realized I needed to ask a question.

I have a couple leak sensors in the attic, one is a SmartThings and the other is Tuya.

It can get as hot as 100Ā° here occasionally in the summer these days, that's still pretty rare but we do see a fair number of days in the mid-90s.

Sounds like you're saying that having batteries in the attic in that kind of heat is not a good idea.

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40

So ymmv of course but in general the hotter the less optimal the battery situation.

Here's some jibber jabber:
https://www.sciencedirect.com/science/article/pii/S1002007118307536

tldr:

  1. Conclusions
    Thermal challenges exist in the applications of LIBs due to the temperature-dependent performance. The optimal operating temperature range of LIBs is generally limited to 15ā€“35 Ā°C. Both low temperature and high temperature out of this scope will affect the performance and may cause irreversible change to the LIBs.

:boom:

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There are words like "fire" and "explosion" in that article.

Looks like I need to figure out how to put the leak sensors on power. The Tuya seems like the likely target, as the sensor and the body are already separated so I wouldn't have to do any modding other than getting power to the body...don't want to run power to a leak sensor like the Samsung where the body is sitting in the water if there is a leak.

OK - so now you've done and created more work for you. I'll need five potential sources for info on modding a battery-device to take direct power. STAT!

:wink:

(Thanks for the warning...)

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42

So the easiest (not cheapest) way is to use something like this..

https://www.amazon.com/dp/B081R5N396/

Just clip the clips off and solder on the battery terminals or use the clips on the battery terminals. whatevah..

Otherwise a little more fancy - need to connect some wires. Solder on the battery terminals.

https://www.amazon.com/dp/B08Z7GLT7N/

Or go embedded... but you need to do some soldering.

https://www.amazon.com/dp/B01MQGMOKI/

Edit: I've done both the first and last ones.. haven't used the second one but it looks cool and is adjustable.

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43

Wow...that was fast. I was still lifting my hands from the keyboard when your reply showed up! :wink:

I have my evening assignement...

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44

So if I go w/option one, since the CR2 is a 3v battery, it's a simple as selecting the 3v version of the Battery Eliminator (sounds pretty scary, if you're a battery). :wink:

I have actually thought up a cleverer (and likely stupider) option...there is a closet directly below where I have the body portion of the Tuya sensor sitting in the attic. The Tuya body is connected to the sensor via a long 3.5mm audio extension cable.

I could drill a small hole down from the attic through the wallboard in the ceiling of the closet, pass the cable through the hole, and then connect it to the body of the Tuya sensor in the closet. Battery never gets too hot, don't have to do any re-wiring in the attic.

Crazy like a fox, or are you getting out the meds?

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