Because one large main pump is responsible for the distribution of flow to each sub-station (such as each floor of an apartment) in central heating systems of large residential complexes and in district heating systems, irregular differential pressure may occur in each district to unbalance and hamper the effectiveness of heating and air conditioning systems despite sufficient heat sources.

By installing differential pressure and flow regulators at junctions of primary and secondary valve systems, it is possible to maintain constant differential pressure for constant flow rate.