Reliability of Heat Pumps Containing R410-A Refrigerant

Abstract

As a result of the Montreal Protocol in 1987 and subsequent approval of the U.S. Clean Air Acts, air conditioning manufacturers in the United States may not produce new products containing Hydrochlorofluorocarbons or HCFC after 2010 because of their potential destruction of ozone in the troposphere. Residential and commercial rooftop units usually contain hydrochlorofluorocarbon 22 , (also referred to as HCFC-22 or R-22). R-22 has been used successfully as a refrigerant in HVAC equipment for over 40 years. High volume production through these years has helped manufacturers to produce reliable products. R- 4104 a hydrofluorocarbon (HFC) mixture, is a leading candidate to replace R-22 in residential and light commercial air conditioners and heat pumps. Most manufacturers do not have enough experience using R-410A to confidently design and build reliable R-410A units. The HVAC industry joined together in 1992 by forming AREP, Alternate Refrigerant Evaluation Program, to share pre-competitive data on alternate refrigerants. One major manufacturer announced a formation of black smudge on internal surfaces of field trial units using HFCs. Several causes were suggested but none were published. Reports of capillary tube plugging were wide spread. Polyol Ester (POE) oils used with HFC refrigerants will break down into acid and alcohol when exposed to heat. Manufacturers have many tools to establish reliability of a product prior to mass production. Units and compressors can be nm on life tests. Prototype test units can be built in the factory and then installed in the field by service technicians. Examples and results from these techniques are described within the paper.