Hey guys. This is my first post here, been lurking for a bit but this thread prompted me to register and post.
Now on to the reason for my post. I really like the RIMS heater desing and when I saw it the first thing I thought, was how easy it would be to ground this device vs some of the other designs. Have you considered using a store bought ground clamp instead of the copper ring or drilling the element?
Clamps similar to this one MONARCH 965 Clamp; Pipe Bonding Bronze For 1/2 To 1 Inch Water Pipe
are used to bond water and gas pipes to ground and would seem to be perfect for this. I had to put this in my last home to comply with code and they can be purchesd from the local big box for a few bucks.