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.
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.