Commissioning Daikin VRV systems

Variable Refrigerant Flow (VRF) systems have commissioning requirements that are very unique to these highly specialized systems. An example are Daikin's Variable Refrigerant Volume (VRV) systems.

The degree of sophistication of these systems demands that the commissioning team either has prior experience or attends the company's specialized training classes. Daikin's courses are held in a variety of locations and are suitable for a diverse audience, including commissioning authorities. Most courses are one to two days in length.

 Commissioning considerations should include knowledge of: 

  1. Strict refrigerant piping rules
  2. Strict refrigerant soldering and connection standards
  3. Triple evacuation is a MUST, including verification by the CA
  4. Strict and atypical refrigerant charging methods
  5. Branch Selector Boxes housing electronic expansion valves for groups of FCUs
  6. 2000 step electronic expansion valves
  7. Refrigerant piping runs as long as 1000' to 3000'+ allowed
  8. No suction traps
  9. Specialized installation and charging tools (flare kits, gauges, etc.)
  10. Inverter controlled compressors
  11. FCUs are grouped - ~ 1 to 6 FCUs per outdoor unit
  12. On some systems, heating and cooling can operate at the same time
  13. Atypical control wiring standards: 18 AWG, stranded, 1 pair, non-shielded, daisy chained
  14. Automatic addressing of the controllers 

It is highly recommended to include paying for factory field inspections during installation and start-up - called "Assisted Commissioning" - particularly if the installing team is inexperienced.


Daikin, a Japanese firm founded in 1924, is the world's second largest manufacturer of air conditioning equipment; outside of North America, they are the largest in the world. In the US, Daikin is number two behind Carrier and reportedly gaining ground quickly.  

Daikin website

ASHRAE Article: Variable Refrigerant flow Systems