New residential and light commercial equipment is moving to lower-GWP refrigerants such as R-32 and R-454B. Both are classed A2L. The label is short, but it changes how some of the work is done.
What do the letter and number mean?
Refrigerant safety groups combine two ratings. The letter is toxicity: A for lower toxicity, B for higher. The number is flammability: 1 for no flame propagation, 2L for lower flammability, 2 for flammable and 3 for higher flammability. R-410A is A1. R-32 and R-454B are A2L. Propane (R-290) is A3.
How flammable is lower flammability?
A2L refrigerants need a relatively high concentration and a strong ignition source to light, and the flame spreads slowly. They are much harder to ignite than A3 refrigerants, but they are not non-flammable. That is the whole point of the separate class: treat them with care without treating them like propane.
What changes in practice?
- Tools and recovery equipment must be suitable for flammable refrigerants. Check the rating on recovery machines, vacuum pumps and leak detectors.
- Ignition sources near a possible release are controlled: ventilation, no open flames, and care with switches and power tools in a space where refrigerant could collect.
- Brazing is done on piping that has been recovered, evacuated and purged with nitrogen, as with any refrigerant.
- Installation instructions for A2L equipment can include minimum room area for the charge size, refrigerant leak detection and mitigation, and specific labelling. Read them for every unit.
- Cylinders for flammable refrigerants are marked differently. Learn the markings used by your suppliers.
What stays the same?
Everything else about good practice: recover rather than release, leak test with nitrogen, evacuate with a micron gauge, weigh in the charge, and verify with superheat and subcooling. R-454B is a blend with small glide, so charge it as liquid.
Where does this fit the Red Seal breakdown?
The Red Seal task matrix includes "Upskills in emerging technologies" (A-2.02) and "Uses refrigerants, gases and oils" (B-7.04), and installation practice sits in D, which is 21% of the exam.
Sources
Examen Studio is independent and not affiliated with the Red Seal Program or Skilled Trades Ontario. This article is a study aid; on the job, follow current codes, regulations and manufacturer instructions.