R22 (HCFC-22), with an ODP of 0.055, is listed as a controlled substance under the Montreal Protocol, and its production is being cut year by year. A large number of in-service central A/C, cold stores and industrial refrigeration systems face retrofit or renewal decisions. Choosing the right alternative requires balancing performance, cost and compliance.

Option 1: R407C — lowest retrofit cost

R407C is a blend of R32/R125/R134a in a 23/25/52 ratio, with pressure-temperature characteristics very close to R22. This means the original compressor, condenser, evaporator and piping usually need no replacement; the work focuses on lubricant change and system cleaning.

Note that R407C has a temperature glide of about 7.2 K and is a zeotropic blend. Once it leaks, the remaining composition shifts, so you cannot simply top it up—recover and recharge the whole cylinder. Also replace the original mineral oil with POE ester oil and change the drier filter.

Option 2: R410A — better efficiency but requires equipment change

R410A operates at about 1.6× the pressure of R22, with about 50% higher volumetric capacity and better efficiency, allowing more compact units. But due to the significant pressure difference, R410A cannot directly replace R22; the compressor, valves and piping must all be changed to high-pressure-rated parts.

Therefore R410A suits scenarios where equipment is near end-of-life and a full replacement is planned, rather than a simple refrigerant swap.

Option 3: R32 — eco-friendly and efficient

R32 is a single-component fluid with no temperature glide; after a leak it can be topped up directly, making maintenance easier than any blend. Its GWP is only 675, about one third of R410A, its volumetric capacity is about 20% higher, and charge can be reduced by about 30%.

R32 is classified A2L (mildly flammable) with a high lower flammability limit and slow burning rate—actual risk is far lower than hydrocarbon refrigerants—but construction still requires ventilation, keeping away from open flame, and dedicated leak detection and recovery equipment.

Key retrofit steps

  • Recover the original R22 using a dedicated recovery machine—never vent it to atmosphere
  • Fully drain the original mineral oil and circulate a system cleaner to remove residue and sludge
  • Replace the drier filter; for blend systems also replace the sight glass and expansion valve
  • Evacuate to -0.1 MPa and hold pressure for at least 30 minutes to confirm no leak and no moisture
  • Charge the new refrigerant in liquid phase by weight, referencing the nameplate and correcting for density differences
  • Run and tune, recording suction/discharge pressure, superheat and subcooling to confirm normal operation

Kaierwen’s technical team can provide customers with R22 retrofit selection evaluation, refrigerant support and on-site technical guidance, helping complete the eco-upgrade at a reasonable cost.