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

5
Retrofitting
Practical cases of retrofitting –
discussion and procedures
There are a series of specific examples for you to choose from:
Domestic refrigerator retrofit
CFC-based domestic refrigerators and small capacity commercial
refrigeration appliances can be retrofitted with a hydrocarbon
blend (a mixture of propane and isobutane), other commercially
available drop-in blends and R134a. For the hydrocarbon blend
retrofitting, there are typically no changes that need to be done to
the refrigeration system.
However, it is essential that the electrical components associated
with the appliance are checked to determine whether or not they
are potential sources of ignition; if they are they must be replaced
with non-sparking equivalent components, sealed or positioned in
an air-tight enclosure. Such electrical components include relays,
thermostat, door switches and possibly bulb-holders.
Safety is the most important consideration while retrofitting with
HC blends. For retrofitting with R134a, major components like the
compressor, capillary, and filter dryer might need to be changed.
These will make the cost of retrofit very high and uneconomical.
Thus retrofitting with R134a is normally not recommended.
Retrofitting with HC blend or other drop-in blend could achieve a
similar reliability and energy performance as the original equipment.
Retrofitting MVAC systems
MVAC can be retrofitted with R134a, the only accepted refrigerant
by car manufacturers worldwide. However, due to compatibility
issues, the lubricant oil, O-rings, filter dryers and dual pressure
switches may also need to be replaced. The essential point is to
get the system flushed and cleaned and to be made fully leak-tight.
This may be termed as simple or economic retrofit. In this case
there will be slight loss in cooling capacity.
Recently, a more simplified retrofit approach has been adopted: just
adding lubricant (PAG) and charging the system with R134a (80%
of R12 charge) is believed to be compatible for MVAC retrofitting by
some experts in the MVAC sector.
Most car manufacturers have also developed specific retrofitting
kits and procedures for their various models. The OEM retrofit
procedure will provide the greatest assurance of comparable
performance of retrofitted to the original MVAC. But in most cases,
the cost may be relatively high.
For the retrofitted MVAC with R134a, the cooling capacity
and energy efficiency would be slightly reduced depending on
the various factors, but nevertheless, such energy penalty is
acceptable. There is no reported increased failure rate of the
retrofitted R134a MVAC compared with the original produced one.
However, due to the higher R134a operating pressure, a reduction
of cooling performance may occur during city traffic operation.
MVACs are also retrofitted (drop-in mode) with HC blend in some
states of Australia, USA and Canada.
Although, in general, car manufacturers do not condone this option
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