yes, you do need to adjust some valves. think of it like this, you only want the pump to suck water from the spa, then after heating that water, you only want the heated water to return to the spa. you have several valves, let me try to look closer.
did this last year. paid the 350 and now i can run everything at the same time. you should not ever have to upgrade it again.
smooth process just have to have someone home so they can re light the water heaters
i would want the swcg done and completed. just my .02.
saw that you are in chico! i had never heard of that place until a year ago. my new neighbors are from chico. they are loving willis texas now!
good luck with the build and communication.
the part above makes me think that there is not 220 at the heater, above says "2-70amp breakers " that should be a double pole breaker providing the sub with current.