If like me you ever wondered how the cheap, off-the-shelf filament dryers might work, well I got it it figured, having done some measurements on the one I got (above). Do they use PWM or a PID to keep the temperature on target? Heck, no! You’re obviously thinking too hard. Let’s strip it down to basics. First, there’s a fan, which runs continuously, regardless of whether or not it needs to. Second, there is a heating element blown over by the fan, to pump hot air into the enclosure and which turns on-or-off like your grandmother’s thermostat, but with far worse hysteresis. Yep, that about do it. 19th century design, built with the cheapest parts, but gussied up with an LED screen, because, you know, customers want technology. 
On average it burns about 40ish watts.
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