What every engineer needs to
know about A2L ignition hazards

The new reality

HVAC is going greener—with risk

  • A2L refrigerants offer lower Global Warming Potential (GWP) but are mildly flammable
  • New UL 60335-2-40 standards require components to not ignite in A2L environments
Comparative Analysis of Refrigerant Types: Safety, Environmental Impact, and Composition
Refrigerants Type R-410a R-22 R-466a R-32 R-454b
Risk Potential Non flammable Non flammable Non flammable Mildly flammable Mildly flammable
Ozone Depletion Potential (ODP) 0 .05 0 0 0
GWP 2,088 1,760 733 675 466
Safety Classification (ASHRAE) A1 A1 A1 A2L A2L
Blend Type R-32/125 Not a Blend R-32/125/CF3I Not a Blend R-32/1234yf
  • Refrigerants Type: R-410a
  • Risk Potential: Non flammable
  • Ozone Depletion Potential (ODP): 0
  • GWP: 2,088
  • Safety Classification (ASHRAE): A1
  • Blend Type: R-32/125
  • Refrigerants Type: R-22
  • Risk Potential: Non flammable
  • Ozone Depletion Potential (ODP): .05
  • GWP: 1,760
  • Safety Classification (ASHRAE): A1
  • Blend Type: Not a Blend
  • Refrigerants Type: R-466a
  • Risk Potential: Non flammable
  • Ozone Depletion Potential (ODP): 0
  • GWP: 733
  • Safety Classification (ASHRAE): A1
  • Blend Type: R-32/125/CF3I
  • Refrigerants Type: R-32
  • Risk Potential: Mildly flammable
  • Ozone Depletion Potential (ODP): 0
  • GWP: 675
  • Safety Classification (ASHRAE): A2L
  • Blend Type: Not a Blend
  • Refrigerants Type: R-454b
  • Risk Potential: Mildly flammable
  • Ozone Depletion Potential (ODP): 0
  • GWP: 466
  • Safety Classification (ASHRAE): A2L
  • Blend Type: R-32/1234yf

How ignition happens

Even low-energy events can trigger ignition

  • Contact arcs during switching can ignite leaked refrigerant
  • Hot spots & flammable housing materials add to the danger
  • One spark = equipment failure, fire, or injury

UL tested for safety

For certification, relays must:

  • Pass leak ignition testing (operate in A2L environment without ignition)
  • Contain all arcs inside sealed housings
  • Use flame-resistant materials that self-extinguish

Cost of getting it wrong

  • In 2023, more than 60,000 HVAC units recalled for fire risk.*
  • No UL listing = No market access
  • Failed safety testing leads to redesigns, delays, & compliance headaches

*Source: www.cpsc.gov

Certification isn’t easy

  • 3 to 6 months of testing & paperwork
  • Cost thousands per component
  • Failure means lost time-to-market advantage

Certified relays ready to deploy

TE Connectivity’s A2L-Certified Relays are UL-tested and ready to go

  • Skip additional end-product ignition testing
  • Save time and cost in compliance
  • Drop-in replacements for legacy footprints

IMB High Load Signal Relays »

SMD or THT, up to 400 VDC switching 

T92 Two-Pole Power Relay »

Up to 50A, 277VAC switching capability

Schrack RT2 Power PCB Relays »

Switching up to 400VAC, 10 A