Help: Thoughts on heater placement

[Maculosa]

I have a 7 gal that has been running for about a year now with a submersible Aqueon Pro heater suctioned to the back glass. I've been considering moving the heater to be resting on the sand along the back wall (touching sand, glass, and live rock).
Will this work? Will it be bad for rock, sand, or glass to be touching the heater?

 

[csammis]

You mean laying it on the sand as opposed to just suctioned to the glass down low and horizontal? You won't get water flowing all around it and that may lead to uneven heating.