The temperature setting on mine is fixed, non-adjustable. I think my heater is an Attwood. My drain has a 3/4" NPT nylon pipe plug in it. I use a combination wrench to get it out.
2006 23B Hybrid with 10k round bar WDH
2011 F150 4x4 SCREW Ecoboost, Max Tow, Integrated TBC, 3.73 LS axle, Firestone Ride Rite airbags.