Comparing a boat’s ice box conversion unit’s performance to a home refrigerator
or even to an older boat refrigeration
system is a mistake. A home refrigerator
is designed around a cabinet size with each component selected to collect and dispose of a given amount of heat energy. Home refrigerators are also assembled, serviced and tested in a controlled environment
your boat’s ice box conversion unit is not treated with the same quality control; this is why performance varies from one boat
Small 12/24 volt ice box conversion units in the past were advertised so the consumer would believed one unit could be efficient in various size boxes. In the last 10 years when buying
a 12/24 volt conversion refrigeration
unit there are over one hundred options to choose from, compressor
size and speed selection, evaporator size and type, and various heat removal
mediums. A small conversion refrigeration unit will be efficient and perform properly only when the right unit is selected, installed correctly and the insulation
is sufficient to deliver the desired box temperature in a planned geographic climate cruising area. The causes of poor refrigeration performance can usually be corrected by first identifying the deficiency and then correcting it. If a refrigeration system satisfies the desired temperature in the box its performance is good. If the daily power consumption
is higher than expected, then conditions that effect short compressor
run times or long run time high temperature/pressures, need to be investigated.
The most common causes of poor performance on small 12/24 volt refrigerator are:
• Poor airflow through condenser.
• Condenser fan is not shrouded.
• Heated air that passes through condenser is allowed to pass through it again. Air cooled condensing units are designed to be efficient when boat’s interior
ambient air temperature is between 70 to 90 degrees F.
• On condensing units cooled by water
, poor or excessive water
to refrigerant heat transfer will lower overall performance.
• Compressor cycles off and on too often.
• Too much refrigerant, this is even possible on a new pre charged units.
• Small amount of refrigerant was lost
of line connectors or the system has a small leak.
• Thermostat incorrectly installed.
• Compressor speed too fast or too slow.
• Air or incorrect gas mixture in refrigerant.
• Very old box insulation
or when insulation is wet or VIP insulation has failed. Box insulation is easily evaluated by comparing insulation exterior surface temperatures against boat interior
air temperature. If insulation’s exterior surface temperature is less then five degrees cooler than boat interior air temperatures insulation is generally considered expectable.
Common misunderstandings about small 12/24 volt boat ice box conversion refrigeration units:
Most refrigeration mechanics do not know how to correctly service
and make repairs
do to complicated marketing
• The shorter the compressor run time the more efficient the system is, not true, on variable speed models they will run longer and are more energy efficient when running at a slower speed.
• Poor refrigeration performance is generally related to lack of insulation, not true, but high energy consumption
might be linked to lack of insulation.
• A eutectic holding plate with less surface area than the recommended size of a thin plate evaporator are more efficient than thin plate evaporator is not true. Eutectic solution separation do to age is another problem with eutectic plates.
• Water cooling
a small 12/24 volt unit will provide better performance than air cooling
, only true in rare cases and never more reliable than air cooling.