ASHRAE proposed changes that would have added the provision of addendums “D” and “H” of ASHRAE 15 to the 2021 edition of the IAPMO Uniform Mechanical Code. Following the agreement between the two organizations, text from ASHRAE 15 would have been extracted and printed verbatim in the UMC.
The extraction policy has worked well for many years, with coordination so that the UMC had the latest requirements in Chapter 11 for refrigerant systems. Addendum “D” of ASHRAE 15 contains the requirements for the use of Group A2L refrigerants in high-probability (direct) systems used for human comfort. This change would have allowed the use of low-global warming potential (GWP) refrigerants currently listed by ASHRAE 34. The extract of Addendum “H” would have updated the requirements for the use of Group A2L refrigerants in machinery rooms.