Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

5
Summary 5.1. General retrofitting guidelines
This section addresses the approach and working
procedures for changing refrigerants within an
existing system. It provides guidelines for the use
of drop-in refrigerants as well as for retrofitting of
both stationary and mobile systems. It includes a
range of procedures specific to certain types of
common systems.
Upon completion, the technician should be able to:
• Introduce the proper use of drop-in refrigerants
• Identify the procedures for retrofitting
chlorofluorocarbon (CFC) and
hydrochlorofluorocarbon (HCFC) based
systems
• Introduce the procedures for mobile vehicle air
conditioning (MVAC) systems
• Discuss the main aspects involved in retrofitting
domestic refrigerators and MVACs
Retrofitting
Getting started
In general, the retrofit of an equipment or installation means to
substitute older parts for new or modernised ones in order to
improve the performance. In RAC recently, retrofit has come to
mean the procedure of replacing ozone depleting substances
(ODS), or hydrofluorocarbon (HFC) refrigerants in existing plants
with zero ozone depleting potential (ODP) or zero GWP refrigerants.
Retrofitting usually requires modifications such as a change of
lubricant, replacement of expansion device or compressor. If the
conversion does not require such major modifications, the alternate
refrigerant is called a drop-in replacement, or retro-fill process.
Retrofitting from an ODS-using system to an ozone-friendly
refrigerant requires a thorough investigation and study of the system.
Some factors must be taken into account:
• Retrofit the system if it is more cost-effective than replacement.
If a major repair (e.g. compressor change, etc.) or modification
of an ODS using system is necessary it shall be evaluated if
retrofit can be done at acceptable cost.
• Properly working and leak-free systems are not recommended
for retrofit, at least until there is a need to open the refrigeration
system for repair. Properly operating systems can continue
operating for many years without causing harm to the ozone layer.
For older systems that are prone to faults, failures and leaks, it
may be more cost-effective to replace the system rather than
retrofit. In addition, new equipment will be more energy efficient.