May • 2013
Phase Out and Retrofitting Options of R22 Systems
R22 refrigerant has been widely used in refrigerating and air conditioning systems since the 1930's. However, the Environmental Protection Agency (EPA) began regulating a phase out of the refrigerant in an attempt to reduce the damage that the product has had on the environment. This has led to an urgent need for retrofitting R22 systems. In considering a refrigerant retrofit for your air conditioning system due to the phase out of R22, here are some pointers that you may want to consider.
There is a wide held concept that all retrofits will work seamlessly if you simply "drop in" the new product. But this is not true, as no two refrigerants will have the same pattern of behavior. The use of drop-ins have also led many to bypass necessary maintenance practices, like setting super heat, changing filter driers, and recovering the original refrigerant. This will in turn affect the performance of the entire system in a negative way.
The US has has the option of choosing from 18 ASHRAE products that can be used as retrofits for R22 refrigerant. Selecting the best retrofit product can be challenging, so understanding a few basic tips helps with the process.
All retrofit refrigerants will be a combination of four basic HFCs. Some will also have additives like lubricants and hydrocarbons in them. Having a basic understanding about how these components work, will
ease the process of choosing the best refrigerant for your system. You should also be aware that while the retrofits will extend the life of your system, it will not address existing problems such as poor circulation of oil.
Refrigerants that are currently available to be used as retrofits are all blends of 400/500 series of ASHRAE numbers. If you find a particular blend of refrigerant to function unsatisfactorily, then avoid using similar blends, as they will most likely also disappoint. Be cautious when using high glide blends, as they are susceptible to fractionation and are not recommended for use in flooded evaporator type retrofits.
Systems that have developed refrigerant leaks present the perfect opportunity for retrofitting. You may be retrofitting an old system due to some leaks, however, since HFCs in the retrofit refrigerant do not expand as R22 does, this could lead to some new leaks induced by the retrofit. To minimize the chances of new leaks, it is recommended that all the critical seals including the Schrader valve cores and caps are replaced during the retrofit.
All R22 retrofits are basically HFCs that use POE oils or polyester oils which are immiscible with alkyl benzene (AB) and mineral oil (MO). But there are 12 retrofits that are classified as "no oil change refrigerants" or NORs. If MO or AB is being used in such a system, then it will hinder with the proper oil return and will also affect the oil lodging. This will lead to decreased system performance. To avoid this, you should ensure the proper use of POE and maintain good piping practices.
Since the proper working of R22 retrofits requires a higher mass flow rate, you may have to replace the expansion valve to bring about the required flow rate. The replacement of the expansion valve will require a proper assessment of the other system components which will affect the system's performance. You should also have a complete evaluation of the system loading as the retrofits can produce changes in the capacity of the system, especially at higher ambient temperatures.
Knowing the application for the retrofit is essential. Since low pressure refrigerants clearly have reduced capacity, they are usually used in higher temperature systems, such as air conditioning. Likewise, high pressure retrofit blends are best for refrigeration only. At higher ambient temperatures, all R22 retrofits effect system capacity,
Understanding the issues and limitations of R22 retrofits will help you in the process of replacing your air conditioning system.