New answers tagged tankless
Despite being obscured behind the wall, it turns out that the two water heaters were indeed in series, the right side feeding into the left side. I accepted the other answer tho since it is probably more helpful in the general sense.
Yes, most larger "whole-house" units require two or even three circuits. Problem is most of those require two or three 40, 50 or even 60 amp circuits. You will have to do some research to find one that will supply your needs but only requires three 30A circuits. I will say, don't get your hopes up.
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