Inlet vent should be located at the bottom (as low as possible) and the outlet vent at
the top of the refrigerator (as high as possible); this supports the natural flow of
convection of heat from cool (bottom) to warm (top).
A vent of 20 to 30 square inches is recommended at top
and
bottom.
2.6 General Electrical Installation
Good performance and efficient operation of the refrigeration system depends on a good
electrical installation that will deliver power to the system with a minimum of voltage loss.
If the boat’s electrical panel cannot deliver the required power with no more than a half volt
of loss the circuit may need to be connected directly to the boat’s main battery switch.
In either case the circuit that supplies the power to the refrigerator must be protected with
either a 15 amp fuse or circuit breaker. Always use a separate dedicated circuit to power
the refrigeration system. Remember that the negative connection is equally important in
delivering power to the unit.
Use a good quality marine duplex wire to make the connection between the unit and the
power source. Tinned cable is recommended because it will give better resistance to cor-
rosion and long service life.
Keep the length of the run as short as possible.
For runs up to 10 ft. use 12 gauge wire (12/2 duplex).
For runs up to 30 ft. use 10 gauge wire (10/2 duplex).
Make sure the circuit is not connected to the power source while making these connec-
tions.
3 Boat’s Electrical System
A refrigeration system when properly installed and operating efficiently will still be a major
consumer of electrical power. It is important to make sure that the boat’s electrical system
is in good order and is large enough to supply the power required. A good rule of thumb is
reserve between 75 to 100 ampere hours of battery capacity in the main house battery
bank for supplying the refrigerator. It is also a good practice to reserve a separate battery
bank for starting the engine.
The connections to the battery switches and electrical panel need to be large enough to
supply power with a minimum of voltage loss.
Battery Chargers - Most modern battery chargers have regulation circuits that will allow
them to charge the boat’s batteries continuously. This also means that they will be able to
supply power to the refrigeration system when shore power is available. Make sure the
battery charger has this feature. A charger with at least a 10 amp output is recommended.
The charger must always be connected to the battery and never directly to the refrigera-
tor’s electronic unit. (Fig. 13).
Alternators - Most marine engines are equipped with an alternator that is mainly intended
for charging the engine starting battery. In order to also charge the boat’s house batteries
quickly and efficiently it is good to increase the size of the charging leads. Installing a high
output alternator with a separate regulator that will directly sense the voltage in the house
batteries is a good way to improve the charging to the house bank.
