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A2L Refrigerants Just Rewrote Your BAS Sequences · NOXTalks

• 0:07
  SPEAKER_00: Welcome to Knox Talks, the AI-generated podcast exploring the groundbreaking ways technology shapes our built environment.
• 0:14
  SPEAKER_00: Today we're diving into how a refrigerant rule you probably skimmed last year just handed your building automation system a life safety job it didn't have before.
• 0:23
  SPEAKER_00: And if you've swapped a rooftop unit anytime in 2025, congratulations.
• 0:28
  SPEAKER_00: Your control scope got bigger and nobody sent you a memo.
• 0:32
  SPEAKER_00: Here's the setup.
• 0:34
  SPEAKER_00: On January 1st, 2025, the EPA's technology transitions rule under the AIM Act took effect.
• 0:41
  SPEAKER_00: For most new comfort cooling equipment, refrigerants now have to come in under 700 GWP.
• 0:47
  SPEAKER_00: That pretty much ended R410A in new builds and kicked off the A2L era, mostly R454B and R32.
• 0:56
  SPEAKER_00: The A means low toxicity, the 2L means mildly flammable, with a burning velocity under 10 centimeters per second.
• 1:04
  SPEAKER_00: Slow burning, low energy, not dramatic, but flammable enough that the code writers took notice.
• 1:11
  SPEAKER_00: And when code writers take notice, the control scope expands because A2Ls are mildly flammable, Ashray 15-2024, Ashray 34-2024, and the 2024 International Mechanical Code, all added requirements your BAS has to honor.
• 1:30
  SPEAKER_00: UL60335-2-4 now requires factory-installed refrigerant detection systems, or RDS, on most new indoor units.
• 1:42
  SPEAKER_00: And that sensor doesn't just beep.
• 1:44
  SPEAKER_00: On a leak event, it's expected to trigger an alarm class, activate machinery room ventilation, and in many cases, command isolation valves or shut the equipment down.
• 1:55
  SPEAKER_00: That whole chain of actions lives in your sequence of operation, which means your BAS is now part of the life safety response.
• 2:03
  SPEAKER_00: Here's the fun fact nobody mentioned.
• 2:06
  SPEAKER_00: Daiken's own A2L engineering guide says high probability systems, that's basically rooftop units, air handlers with DX coils, water source heat pumps, anything that could leak refrigerant into occupied space.
• 2:19
  SPEAKER_00: Now ship with RDS as standard.
• 2:22
  SPEAKER_00: The sensor is already on the unit.
• 2:24
  SPEAKER_00: The open question is whether the installing contractor actually wires it into the BAS and programs the response.
• 2:31
  SPEAKER_00: And that's not hypothetical.
• 2:33
  SPEAKER_00: Plenty of replacements are going in right now where the refrigerant detector is sitting there, wired to nothing, because the mechanical spec assumed the control spec would cover it, and the control spec assumed mechanical had it handled.
• 2:46
  SPEAKER_00: Another fun one, the 2024 IMC added shaft requirements for a 2L piping, fire rating, continuous ventilation, and leak detection inside the shaft itself.
• 2:57
  SPEAKER_00: If your building has riser piping running through occupied floors, and you're replacing equipment that uses A2L, there's a real chance the shaft needs an upgrade, not just the unit.
• 3:10
  SPEAKER_00: And guess what ties the shaft ventilation to the leak detection?
• 3:14
  SPEAKER_00: Your BAS.
• 3:15
  SPEAKER_00: Here's where it gets patchy.
• 3:17
  SPEAKER_00: Code adoption isn't uniform.
• 3:19
  SPEAKER_00: The 2024 I codes are being picked up at different speeds across states and cities.
• 3:24
  SPEAKER_00: Florida famously runs a few years behind the model codes.
• 3:28
  SPEAKER_00: Some jurisdictions adopt parts of the mechanical code and amend others, which means two buildings with identical equipment in different cities can have completely different BAS requirements for the exact same refrigerant leak event.
• 3:41
  SPEAKER_00: Your AHJ, the authority having jurisdiction, is the person who tells you which version of the rules applies on your project.
• 3:49
  SPEAKER_00: Call them early.
• 3:50
  SPEAKER_00: Every A2L project needs that call, ideally before the purchase order, definitely before commissioning.
• 3:58
  SPEAKER_00: So what does this mean on Monday morning?
• 4:00
  SPEAKER_00: Three things.
• 4:01
  SPEAKER_00: First, add an A2L sequence audit to your equipment replacement checklist.
• 4:06
  SPEAKER_00: Before you energize a new unit, confirm three things.
• 4:10
  SPEAKER_00: The refrigerant detection system is physically wired to the BAS, the alarm class is programmed, and the interlocks to exhaust fans and isolation valves have been tested.
• 4:19
  SPEAKER_00: Not assumed.
• 4:21
  SPEAKER_00: Tested.
• 4:22
  SPEAKER_00: Second, update your sequence of operation template.
• 4:25
  SPEAKER_00: If it still looks the way it did in 2022, it's missing refrigerant detect alarm classes, machinery room exhaust staging, and emergency shutoff valve logic.
• 4:35
  SPEAKER_00: Your SI or controls engineer has probably already figured this out on one project.
• 4:40
  SPEAKER_00: Make it the standard on all of them.
• 4:42
  SPEAKER_00: Third, get your AHJ involved at the design phase, not at the final inspection.
• 4:47
  SPEAKER_00: A 2L requirements vary enough that assumptions get expensive fast.
• 4:52
  SPEAKER_00: A 10-minute call with the code official before the mechanical package goes out can save you a change order and a delayed occupancy.
• 4:59
  SPEAKER_00: The bottom line is simple.
• 5:01
  SPEAKER_00: The rooftop replacement you're scoping this quarter isn't just a mechanical project anymore.
• 5:06
  SPEAKER_00: It's a mechanical project, a life safety project, a code project, and a controls project, all running on the same schedule.
• 5:15
  SPEAKER_00: If you plan it that way from day one, you'll hit your occupancy date.
• 5:19
  SPEAKER_00: If you plan it the old way, you'll find out at commissioning that your brand new unit has a refrigerant sensor that doesn't talk to anything.
• 5:27
  SPEAKER_00: And that's a conversation nobody wants to have with a tenant.
• 5:30
  SPEAKER_00: Small rule, big downstream, that's A2L.
• 5:37
  SPEAKER_00: Futurist flights flow.
• 5:45
  SPEAKER_00: Innovation spots fly.
• 5:49
  SPEAKER_00: In the channels of life.