Shedding a on-demand water heater

[frofro19]

Whats the best way to shed a on-demand water heater that has 2 double 40 amp breakers supplying it? Would you use 2 smart modules?

 

[LarryFine]

Or one module controlling one 4p or two 2p contactors.

 

[tom baker]

suggest looking at the controls to see if there is an inhibit input, or interrupt the control circuit