I am installing a new chiller in a building which has three other chiller, total capacity 3000kW. The chillers feed a ten storey building and the terminal units are two port control. Overall volume of the system is about 10 metre cube.

Because the system is a two port system, the chiller manufacturer tells me that I need a buffer vessel. he tells me that the water content in the secondary side cannot be included in the water content calculation. The water in the primary circuit is insufficent to stop the chillers trying to start too many times.

is this true? Is the buffer vessel the correct solution? Seems to be a waste of kit and space.