Ideas to monitor an old gas range?

I have a GE gas range with no real smart features. I would like to be able to track when it is on for an automation to run an exhaust fan. I’m thinking about putting a temperature sensor in the range hood, with a trigger when the temperature goes over the room temperature by 20F. Has anybody done this? What was your experience? Or do you have a better idea than a temperature sensor?

Thanks!

I did exactly that (and used a cheap smoke detector to also trigger on smoke).

Did it quite a while ago before I had even heard of HA. I’ve since switched over to ESPHome and it’s still working well. Only thing is I suspect the smoke sensor isn’t working quite as well, as when I made the switch and re-setup the parameters for changing fan speed based on smoke levels it seemed like it was affected quite a bit by fan speed. Still works, just can take quite a while before it actually ramps back down and off (I find myself just manually shutting it off when I’m done cooking sometimes).