I bought Sunlu Filament dryers. The operational concept is all wrong. You set a temperature and timer. I just ordered a temperature and humidity controller (24vdc) from Amazon, but it is also commonly on eBay: https://www.amazon.com/gp/product/B08ZKDY556/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 Added a 24v relay because I assume the grounds are common and I want the two outputs in series: https://www.amazon.com/gp/product/B08ZKDY556/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 While the humidity is not low enough the heater will turn on to the max temp programmed.. I may even mount a fan in my printed box.. The big advantage is that: I no longer have to keep pressing buttons on the Sunlu Box, I will not waste money heating filament that is already dry enough. Set it and forget it. Parts are coming from China. When they arrive I will update. This works really well. The SFX-ST3022-24V has relays with isolated contacts. (eBay or Walmart) On the PCB one side of the relay contacts can be jumped to 24v(-) the other relay can be jumped to 24v(+). The 24v from the rear connector can be directly soldered to the PCB and the heater can now be directly soldered to the relay contacts. I glued the sensor to the inside of the box cutting a double sided sheet (for gluing glass to flexplate). I reduced the length of the sensor wires. I then used the same double sided glue sheet to glue the module to the front of the Sunlu box. There is about a 3C and 3% RH hysteresis once installed. This is set and forget, no having to push buttons before the 24 hour time is up. It save energy by not requiring heat unless the RH% drops.