Ran into a situation at a church where the 17 kw on-demand water heater was switched out for a 14 kw heater. The original heater was on 2 double 40 amp breakers and the new heater was calling for one double pole 60 amp breaker. It was hooked up splitting the 2 elements by using the existing wire on 2 double 40 amp breakers. I advised it should be on one 60 amp breaker. I wasn't sure if both elements in an on-demand come on at the same time or not. Is there any issue leaving like it is, or should I tell them it needs to be changed? If one breaker trips, then all the currect, (58 amps) would be on the other breaker which should cause it to trip as well.