Used in closed loop design. In conjunction with boilers having high resistance (condensing) or when total flow rate of all parallel running circulators is higher than maximum flow rate of the boiler, the low-loss header provides hydronic separation, decoupling boiler and system circuits from each other. It is recommended to use the low-loss header in applications in which the total system flow rate exceeds the maximum boiler flow rate. PAW strongly recommends the use of a hydronic separator in cases where the system head and flow rate are unknown.