Guideline 41-2023 -- Design, Installation and Commissioning of Variable Refrigerant Flow (VRF) Systems

Guideline 41 was developed by ASHRAE to provide information and guidance relating to the design, installation, and commissioning of variable refrigerant flow (VRF) systems. The guideline is intended to expand on the basic information currently provided in ASHRAE Handbook—HVAC Systems and Equipment, Chapter 18, “Variable Refrigerant Flow.” In particular, enhanced guidance is provided on installation, commissioning, start-up, and operation.

The 2023 edition of the guideline includes the following key updates:
* New guidance for modeling an HVAC system that includes variable-refrigerant-flow (VRF) equipment
* Clarification of how the VRF internal system controls work both as stand-alone and when interfaced with third-party automation and controls systems and devices
* Additional commentary on proper methodology for complying with outdoor ventilation requirements when using VRF systems
* Updates to climate zone and seismic survey maps

For a full list of changes in the 2023 edition, see Informative Appendix A.