What is the buffer tank and when should be installed in an air to water system?

The buffer tank is an insulated tank that is being installed in the cool water circuit right after the heat exchanger of the chiller. Its purpose is to collect the cooled water that is produced by the heat exchangers, in order the circulator to pump cool water from the buffer tank and this way is ensured the constant and regular flow of cool water to the local units (fan coils etc). Usually is accompanied by safety and air purge valve. The storage of the buffer tank depends on the total quantity of the circulated water in the installation (l/min) and on the nominal cooling capacity of the system (kW).