I also looked at something similar earlier today with my bathroom fan, setting up a rule to turn it off after a period of time. It doesn't solve your app based approach, but thought I'd mention it as an alternative in case you find it useful. I also plan to try out @bertabcd1234 's app as well. I have a couple of virtual switches on my dashboard I use as a way to turn off lights more quickly than their timeout setting if I want, which would fit nicely into that model.