but not a full submersible. i use the exact same type, although not by hagen.
the heater hangs vertically in the aqurium, usually by suction cups or some type of holder. as far as i know, if the awauarium is glass, having the heater touch it shouldn't be a problem. but don't take my word for it. thats just what the LPS guy said 3 years ago, and he misled me on many things anyway. i do know for sure that if your aquarium is acrylic and the heater touches the side, the acrylic will melt.
so, if you can find a way to hang it, keep it hanging vertically on the side, submersed up to the water line.
hope that was helpful for you!