R421a Refrigerant

R421A is a non-ozone-depleting, two-component hydrofluorocarbon (HFC) refrigerant designed as a drop-in replacement for R-22.

Composition and Properties

R421A consists of 58% R-125 and 42% R134a, making it a two-component blend with low temperature glide, which ensures consistent evaporator temperatures and efficient system performance It has an ozone depletion potential (ODP) of 0 and a global warming potential (GWP) of 2,631, making it environmentally safer than R-22.

The refrigerant is ASHRAE A1 rated, meaning it is non-toxic and non-flammable.

R-421A is designed to retrofit existing R-22 systems without requiring major modifications. It is compatible with mineral oil (MO), AB, and POE oils, and in most cases, no oil change is needed when converting a system.

The refrigerant has a pressure-temperature relationship nearly identical to R22, allowing technicians to use existing gauges, line sets, and TXV orifices without significant adjustments.

However, if the vertical height difference between the evaporator and condenser exceeds 20 feet, conversion to POE oil may be recommended.

R421A can be used in air conditioning, medium, and high-temperature residential, commercial, and industrial refrigeration applications.

It is important not to mix R421A with R22 or other refrigerants, as this can lead to improper operation.