A chiller system including an evaporator for evaporating a refrigerant and a water pipe in fluid communication with the evaporator. The water pipe is configured to allow water to pass through at a flow rate and to circulate the water with the evaporator to exchange heat with the refrigerant in the evaporator. The chiller system includes a flow restrictor tube within the water pipe that is configured to allow the water to flow through the flow restrictor tube at a reduced flow rate relative to the flow rate. The chiller system also includes a measuring probe that passes through walls of the water pipe and the flow restrictor tube and includes an accuracy range of flow rates less than the flow rate. The measuring probe is configured to measure the reduced flow rate within the flow restrictor tube where the reduced flow rate is within the accuracy range.