ASHRAE Just Changed the Game for A2L Refrigerant Piping.
Ventilated shafts are no longer always required. What changed?
ASHRAE’s 2024 update introduces a key change: under certain conditions, developers using A2L refrigerants (like R-32 or R-454B) may no longer need to run piping through a shaft.
The Challenge
With the shift to A2L refrigerants now well underway, developers are adjusting designs to comply with fire and safety codes. Here’s the catch:
ASHRAE 15-2024, Addendum A
- The new exception (Section 9.12.1.5.1) states:
A shaft enclosure shall not be required if piping meets any of the following:
- Uses A2L refrigerant
- Has continuous, tested piping and joints (per Section 9.13)
- Is located on exterior walls
- Meets concentration thresholds from ASHRAE 34, Tables 4-1 or 4-2
In short: You may be able to eliminate the shaft altogether.
Ready to Find Out If Your Project Qualifies?
Let us review your project and save you from unnecessary expenses.
Thank you,
Blair Hildahl
BASE4 Principal
608.304.5228
BlairH@base-4.com
Source:
1.ASHRAE 15-2024 Addendum A – Section 9.12.1.5.1 (Shaft Alternative)
2.ASHRAE 15-2024 – Section 9.13 (Leak testing + pressure integrity)
3.IMC 2021 – General shaft and mechanical enclosure requirements
4.ASHRAE 34 – Concentration tables for refrigerant classification
