When I start my brew day, I turn the propane burner on the kettle, then go off and do something else as it takes a half hour or so to heat 9 gallons or so water to my strike temperature of around 175°F. About three quarters of the time I overshoot that, and find boiling water, which I then have to shut off and let cool or add cold water to knock the temperature back down.
Which got me thinking. I could hook up my Joule that I used for sous vide cooking, then I could remotely monitor the temperature with the app on my phone. The problem with that idea is: (1) I would have to fill the 15.5 gallon kettle high enough for the Joule to properly circulate, and (2) the Joule has to be plugged in, and draping an extension cord over an active propane burner seems like a bad idea.
Seems like there ought to be something like this already on the market. I envision a battery operated floating digital thermometer that can connect to a phone app. But searching the internet, I find nothing. Any ideas?