R-410A

R-410A is a near-azeotropic mixture of difluoromethane and pentafluoroethane which is used as a refrigerant in air conditioning applications. Unlike many haloalkane refrigerants it does not contribute to ozone depletion, and is therefore becoming more widely used as ozone-depleting refrigerants like R-22 are phased out.

While R-410A was invented and patented by Allied Signal (now Honeywell) and Honeywell continues to be the leader in 410A capacity and sales, other producers around the world have been licensed to manufacture and sell the product. R-410A was successfully commercialized in the air conditioning segment by a combined effort of three companies. Carrier Corporation, Copeland (a division of Emerson Climate Technologies), and Allied Signal worked together in developing the refrigerant for practical use in Air Conditioners in the US. R-410A is also the preferred refrigerant for use in residential and commercial air conditioners in Japan and Europe, replacing R-22. R-410A is marketed under several trade names such as AZ-20, Puron and Genetron R410A. R-410A is incompatible with R-22 refrigerant.

Carrier Corporation was the first company to introduce a R-410A/PuronTM based residential AC unit into the marketplace in 1996. Carrier holds the trademark Puron and is still the leading supplier of energy efficient R410A AC systems for residential, commercial and chiller applications in the US today.

Installation of R-410A systems requires a few things that R-22 doesn't necessarily require. All R-410A systems have a liquid line filter-dryer included, which must be installed. Before and during brazing, nitrogen must be run through the lineset and indoor coil. When using low pressure, it must be below 60 pascals (0.45 mmHg). Like mineral oil used with R22, POE oil absorbs moisture, but unlike mineral oil, POE oil breaks down in the presence of moisture to form acids. R-410A must be liquid charged. On a new installation, additional refrigerant should be added for every five foot section of liquid line after the first 15 feet (typical factory precharge). If a R-410A system is undercharged, one must carefully put liquid through the vapor line. Vapor charging R-410A will contaminate the system. Liquid charging will allow the ingredients to mix in the proper proportions. The operating pressures with R-410A are higher than R-22. Typical head pressure will be somewhere in the 1.9 to 2.6 MPa (275 to 375 psi) range, while suction will be in the vicinity of 1 MPa (150 psi). All R-410A systems use an expansion valve at the indoor coil. If one has a universal coil (one that can use R-22 or R-410A) the valve must be installed and the piston removed. Coils designed for R-410A already have the expansion valve installed. When servicing a R-410A system, the refrigerant must be recovered. In many countries, it is illegal to discharge any refrigerant, including R-410A.

Availability
In the US, although the EPA has mandated that R-22 (Freon) be phased-out, no window-mounted air conditioners are yet available that use R-410A. Instead, only central air conditioners are currently being phased into the new standard.

R410a