One aspect, as provided herein, is directed to a multi-stage fluid control system for a fluid source heat pump system. This embodiment comprises compressors configured to operate as separate, heat exchange stages, condensers each being fluidly coupled to at least one of the compressors by refrigerant tubing and having intake ends coupled together by a fluid intake manifold. This embodiment further includes output conduits coupled to each of the condensers and that are couplable to a distal location. Further included is a modulating valve control system interposed the output conduits. The modulating valve control system is configured to stage a flow of fluid through the condensers based on a number of operating compressors.