All the current heaters are advertised to be submersible. Make sense, heat rises. For the last 5 to 6 years , I gone through average 4 to 5 heater lasted average 11/2 to 2 years because of water got into the control section. You can actually see the condensation inside the heater, H2O and electronic don't mix too well. I need feedback on the subject and recommendation on products are truly designed to be submersible, thank!