I have just finished installing a new Electric water heater. It came prewired
for Double Element Non-Simultaneous operation. Is there any advantage to this configuration? Is there a "most efficient" configuration? It seems to me that
"double element simultaneous operation" would be the best way to go.
Just in case you want to know, I am using a three wire connection(L1 & L2+Grd.)
Virtually all residential electric water heaters (storage tank type) do not function similtaneously. Your heater has two elements probably 4500 watts each or maybe 5000 watts each or the bottom might be 5000 and the top element 4500 watts.
The bottom element heats most of the time and the top generally only on recovery...ie...after a shower
Both elements heating at the same time would increase the circuit load and require a 40 amp circuit instead of 30 amp. Essentially when cold water enters the tank it is carried from the top inlet down through a dip tube and comes out in the bottom of the tank. This inrush of cool water will trip the lower thermostat. As the water cools at the top the lower kicks off and the top heats.
There are models that allow both elements to heat together but these are generally commercial units. In a residence non-similtaneous element heating is suffiecient.
" One nice thing about the NEC articles ... you have lots of choices"