i hear lots of people use this on a popcorn popper to dial down the power

https://www.amazon.com/VenTech-VT-SPD-CTRL-Variable-Controller/dp/B00EVYGPJQ/ref=sr_1_sc_4?ie=UTF8&qid=1530737629&sr=8-4-spell&keywords=rotar+controller

the downside is it will also reduce the fan speed. the best would be if you could wire up this voltage controller for only the heater. the one a friend ended up giving me, he wired the on off switch to control the heater. the fan always blows as fast as possible. if i really wanted to be a bro, i'd wire in a voltage controller in series with the heater, so you could dial it in to whatever you wanted.

that would make the air popper one serious little dude.