What might cause slight corrosion atop a tankless water heater's copper topped element assembly?
I checked all the grounding and reconnected the two element assembly grounding wires and ensured proper tightening. Then, I checked the grounding wire from the tankless unit to my breaker box. I then switched this ground wire from the neutral bar to the grounded bar. There is absolutely no bonding/grounding to a water pipe! I cleaned off all the corrosion.
Could the loose ground wires have caused the corrosion? I began the grounding issue because I discovered a faint pale green stain in one bathroom sink and suspected electrolysis. I have a whole house water processing system installed. I called the manufacturer but, was placed on hold for over 20 minutes. I eventually hung up.