My beloved partner has a habit of cooking her food with as much oil and heat as possible, which means lots of smoke and aerosolized residue. She also has a habit or not turning on the vent fan.
I've been thinking of ways I can automatically turn on the vent based either on smoke or heat.
I thought of perhaps using one of the MQ type sensor and reporting via MQTT, but if there is a more directly compatible option I would be interested in that.
Thanks for any input you might have!
I have a rule that turns on my kitchen lights if motion is active for 10+ minutes. I'm thinking you might be able to do this with a motion sensor and temp sensor like an aotec multi 6. It senses temperature and motion, which would tell you if the stove were on and she is moving by it. If you pair the sensor plugged in to power then it will repeat, and you can have it report quite often to the change, then a certain temp would turn it on. It's a rough thought in my head, but definitely less hoops to jump through. I've noticed that a lot of the motions report temp, but the aeotec can be powered, which makes it idea for frequent reports without killing battery. Just a thought. I have a similar rule that deals with temperature to set the speed of a ceiling fan and it works pretty well. Took some tweaking to determine set points, but well worth it. I'm pretty sure you could place it somewhere it wouldn't get melted, but would sense the air temp change in the area.
Maybe not the best way, but you could use a power meter on the stove cord and control the fan based on the wattage usage. The down side is that the vent would likely be on when you might not need it. For example the vent would come on when using the oven. But if she's anywhere near the cook I am, having the vent on when the oven is running wouldn't be a bad thing! [grin]
That's actually a pretty good idea. For unrelated reasons I've been doing some validation on current sensors.
I do have a bunch of the xiaomi sensors, I hadn't thought of using it for a temperature switch on the stove, that may be a good idea. The reporting interval may not be ideal, but it could be a good start to test the concept.
Xiaomi temp sensors or motion? Do Xiaomi report temp? I didnt think they did?
We use an electric kettle, and primarily cook range top so it would be pretty close to a 100% requirement. We are actually moving, and I'm not sure what the setup is yet, but I will find out soon enough.
I've bought 2 of the Zooz Z-Wave Plus Power Switches (ZEN15) in the last 2 weeks. I have one hooked up to a oil radiator in my bedroom that I'm controlling via Hubitat and am using the other one to test power usage on various devices. Right now it's hooked the the UPS powering my primary PC, multiple monitors, 6 external hard drives, etc. Based on the power used on the last 1.47 days, it cost me roughly $9.65 to run the UPS/PC equipment 24x7 for a month. I'm planning on buying a few more of these in the near future.
I have no idea if this could work and it might be an expensive try. Modify a smart smoke detector to disable the alarm. Put it directly over the stove. If you get almost any smoke it would trigger HE to enable the fan.
Another option is installing a non smart smoke detector directly over the stove. After it went off a few times you might have an automatic response from the cook to turn the fan on before she starts cooking. 
+1 for a smart range hood! The number of times my family either dont turn it on when they should, and/or leave it on for hours once they are done....so begging to be automated.
The problem I see with the smoke detector idea is that it's going to gunk up the sensor pretty quickly if exposed to a lot of smoke and oil on a regular basis. I haven't played with any of the smart smoke detectors (yet), but I wonder if you can even set them to where they don't alarm.
There is no way to disable the alarm through settings. I do agree, the regular smoke and oil do clog up smoke detectors. I have read recommendations that suggest NOT putting them in the kitchen for that reason.
Trust me, you can't. And they trip at the lightest of smoke. We had the windows open one night and someone had a burn pit and my house lit up with buzzes and beeps and lights galore! Very sensitive!
I didn't think you could, but I've not read details/reviews on many of the smart smoke detectors yet.
Something else that may or may not help–I didn’t see anyone reference it yet in this thread. There’s a company that makes LED indicator sensors—people use them on their washing machines to see when the machines are running.
If your stove has a stovetop hot indicator, you could put that over it and use that to trigger it 
Thanks for the Homeseer Light Sensor link. Ordered a couple to try out.
Thanks for the ideas everyone. I think the indicator light sensor idea may be the best way to go if our new stove has such a thing. After that I think a temperature sensor of one kind or another will be my backup plan. More importantly, I'll need to see how the vent is turned on.
If I can figure out a way to set this up before we actually move, then hopefully my beloved partner will simply assume it is automatic without me having to explain anything!
I'm picking up the keys and going to take some measurements tomorrow, so hopefully I can figure it out and install it over the weekend while I wait for the cable man to set us up!
Good luck on the move and have fun!!
Thanks!
We are moved and settled, so now it is time to tackle this issue.
I'm considering using a 16A temperature switch installed in the hood.
It has the advantage of being inexpensive and auto-resetting without requiring any external components. Alternatively I could use it with a controller and relay (or Sonoff) as a sensor to add overrides and other automations.
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