On or off indication for Attic exhaust fan

I have one of those typical round attic ventilators, that just removes the heat from the attic. Is there a device I could add to ST that will tell me if the fan is on or off? I don’t want it controlled by a WeMo switch or other remote switch, just indication.

Is it hard wired or is it plugged in to an outlet or controlled by a switch? If so, the simplest method would to either replace the switch or outlet. If it is plugged in, you could use an external switch (https://shop.smartthings.com/#!/products/smartpower-outlet) to control it.

If you do go this route and need to then control the schedule of a ventilation fan, I wrote an app that does some rather complex schedules (breaking the 4 timer limit of the typical smart things app). Let me know as this is what I did.

It is hard wired and controlled by it’s own thermostat and humidity sensor. It is so quiet that I don’t know if it is running or not. So some way to sense the movement or vibration of the motor would work, but I can’t figure out what to use.

Does it have louvers that snap open / closed when it turns on / off? If so, you may be able to use a magnetic open/close sensor with the magnet attached to a louver…

No just a dome on the roof with a screen mesh and a fan mounted parallel to the roof and the dome, so no place that opens when the fan is on and closed when off.

You can probably attach a battery operated vibration sensor nearby and use that, the way some people do to alert when their dryer stops running. Not something that monitors the power draw, which is more accurate but needs to be wired or plugged in. Just something that senses the shaking and notifies you. Look for forum topics on laundry monitoring.

I am going to try a SmartThings Multi sensor that detects vibration and see if that works. I will post my results.

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attic ventilation goal is usually temperature control to maximize roof lifetime, with a nice side effect of reducing cooling load. So a high temperature monitor would be useful, and the smartsense multi can do that also.

It would be amusing to put the magnet on a blade and the sensor on a brace, and watch the open/close pulses fly by. It would work on those old passive ventilators too. Pretty useless traffic but fun. you can balance with counterweights. Mount magnet as close to shaft or even on the shaft/axle if possible, for the least impact on the fan/vent. I wonder if this is an awful load on the cloud.

You can’t really control humidity in attic but it is nice to know remotely, so I stuck a temp+humidity sensor Up there.

Actually this house is very well sealed and the humidity sensor turns on the fan in the winter to prevent moisture buildup and condensation which is very damaging. And I have used my Smart Sense temp/hum sensor to see if it actually reduces the humidity and the fan does the job. I have neighbors that have moisture dripping from the fixtures on the cathedral ceiling. They installed the same fan and no more dripping. I will just mount the sensor to the motor mount not the motor as I think the heat of the motor might melt the plastic housing.

Nice project, @joelw135!

It will be nice as long as it works. I will post the results.

I purchased the Smart Sense Multi sensor and just attached it to the frame of the fan motor and I now have the temp in the attic and the indication of the fan being on by the vibration sensor. It works great. I don’t use the open close so that is just wasted. I ty-wrapped the magnet to the sensor so it shows closed all the time, but this way I don’t loose the magnet. I just wish they didn’t leave the Hydrometer out of the sensor like they have in the temp/Humidity sensor, as the humidity in the attic during the winter would be helpful.

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Let me ask a stupid question but seriously. If I place a battery operated Sensor in the attic… Can the battery explode due to the heat up there?

More likely to leak than to explode, but just check the operating specs.

135 - 140 degrees is pretty typical for summer heat in an attic, although obviously there’s s lot of variation.

Also, right near a vent is often 10 - 15 degrees cooler than in a more enclosed section.


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I was just curious…:slight_smile:

Well I hope they don’t explode, but I can tell you the temp on the day I had my house inspected was 133 near the attic door, much hotter in the middle away from the door. With the attic fan running the temp near the fan today is 105 degrees, The temp outside in the shade is now 96 degrees so 105 at the fan isn’t bad. I also like that I can see if the fan fails as it is very quiet and the ceilings are very high like 20 feet.


Are there any smart attic fans? I had new roofing installed thru Power home remodeling group which set me back 22K (replaced beam, ply etc.) with top of the line stuff (as they claimed) but they got rid of all attic fans saying that they were no longer required. I am not too sold on the idea though… Made too many mistakes in the first year of home ownership. :frowning:

There is no true smart attic fan but you can come close. My fan has an adjustable thermostat and an adjustable humidistat that lets the fan go on during the winter which removes high humidity from the attic which causes mold and damage to roof and insulation. My home is to well sealed so I have to keep my humidifier off or I get humidity on the windows. I thought it was a cheap humidistat so I replaced it with one that is computerized and reads outside temp. But I wasted my money as the humidity was still to high. So now I keep it off and the inside humidity is around 40+ or-%.

My inside humidity is pretty much between 45 - 58 degrees range now after new roofing and the temp above in the second floor (split level house) for the rooms below attic is significantly higher than the lower floors.in my case it may be the ducts too as in my master bedroom, the cold air velocity is much lower than other rooms on the same floor. Man, I was so much happier living in an apartment. :slight_smile:

I lived in a split level for 30 odd years and found a few solutions that help your problem.

  1. the return air duct on the upper floor was moved up near the ceiling and the down stairs return air I installed a damper so in the summer the falling cold air was drawn to the lower return and in the winter to the upper. The hot air rises so in the winter the upper returns were open to draw the hot air from the ceiling upstairs to the lower floor and the summer the cold air to the upper floors. I hope that wasn’t confusing. I also installed 6" of additional insulation in the attic. and a few duct mounted fans for the upper floor controlled by thermostats. That was the hardest part.but the upstairs and downstairs were much more even. The duct fans are cheap and depending on your house construction the hardest part is getting the wire to them. Usually in your type of system if hot air there is a central duct on the lower floor that feeds the upper floors and some dampers on the lower floor. The fans fit in the ducts that come off the main trunk. it does mean a hole in the ceiling to expose the duct, but easy to patch using the same piece of sheetrock. It is amazing how they made a difference in both summer and winter. The complete job was less than a grand.