Duty & Stand-by Arrangements for VRF and DX Cooling Systems

Summary

Electrical equipment can generate heat. Certain rooms containing electrical equipment must be cooled to remove heat and ensure reliability of the contained equipment.

Cooling systems are used to cool the rooms. Cooling of these rooms can be critical and a backup source of cooling (stand-by) may be required. Depending on the location, Direct Expansion (DX) or Variable Refrigerant Flow (VRF) cooling systems are used in different arrangements to provide duty and stand-by cooling to all the required rooms.

There are two different running strategies that can be used for these systems: hot stand-by and cold stand-by.

This paper explains the benefits of cold stand-by over hot stand-by, in terms of wear and efficiency, and why the cold stand-by running strategy is preferred.