In order to protect the evaporator section in the chiller from freezing, a minimum water flow is required to circulate in the chiller’s evaporator when in operation. The minimum required water flow is recommended by the chiller’s manufacturer. The minimum water flow can be provided with the VFD on the chilled water pumps. The volume of water in the chilled water system should be sufficient enough to provide at least 2 minutes of minimum water flow for the chillers, otherwise a reserve tank (Buffer Tank) should be used. Furthermore, a reserve tank would be required if the volume of water in the system is not sufficient enough to provide 3-6 gpm per ton water flow to stabilize the chilled water temperature.
The water velocity through the chiller should be 3-8 fpm.