VRF & CAN/CSA B52 Refrigeration Code
UPDATED: August 25, 2021
While variable refrigerant flow (VRF) systems offer great flexibility in your designs and can provide outstanding energy savings, there are some code requirements that must be considered. In Ontario, the code of reference is CAN/CSA B52 – Mechancial Refrigeration Code. This code outlines all of the safety requirements that must be met in order for a refrigeration system to be approved for installation.
In this post, I want to specifically address the quantity of refrigerant allowed in any given system.
The first order of business is to define the type of system we are dealing with. VRF systems are classified as: direct with a high probability of leakage. It should also be noted that all VRF systems currently available in North America use R410a refrigerant. Applying the code for different occupancy classifications, the maximum refrigerant capacity in any system is defined as follows:
|Occupancy Classification||MAX Refrigerant Charge
The volume is calculated based on the smallest confined space that refrigerant could discharge into in the event of a rupture. This would include the celing plenum in a non-ducted return application as well as any spaces interconnected by transfer openings, etc.
NOTE: Table 1 in CAN/CSA B52-2018 provides guidance on the max refrigerant charge. However, Note 2 identifies a similar table in ASHRAE Standard 34, which takes precedence over the CSA standard. In the case of R410a, the allowance in ASHRAE is higher than the CSA standard. (25 vs. 13)