Isotherm 4201 ASU Magnum Instructions D'installation Et D'emploi page 2

GB
Operation and installation manual
GENERAL
Isotherm 4201/4701 ASU Magnum is a seawater
cooled refrigeration system for sailing yachts
and motor cruisers. It is designed to generate low
refrigeration temperatures also in the warmest
conditions while at the same time consuming an
absolute minimum of battery power.
This is achieved by using our patented electronic
control system ASU that runs the compressor at 75
% higher speed when the boats engine is running.
This in combination with a holding plate inside
the refrigerator, stores the refrigeration energy
produced for long periods.
The following points are important, to achieve a good
result:
Refrigerator box
To retain as much cold air as possible when opened, a top-
loading box is usually preferable to a side opening one.
A most important factor in achieving good results is that the
refrigeration box is well insulated. Do not use polystyrene
type material. Expanded or cross-linked PVC or polyurethane
insulation material should be used. Recommended insulation
thickness (multiply by 3 for freezers): 30 mm for up to 50 litre
boxes; 50 mm for up to 100 litres and 75 – 100 mm for larger
boxes. If space is available use thicker insulation around the
lower part and in the bottom.
A moveable partition should be installed in the box to allow the
frozen food section surrounding the cold plate to be reduced
to the smallest space possible so that the correct temperature
of 4 – 6°C (39 – 43°F) can easier be maintained in the
refrigeration section. The lid must also be insulated but more
important that it fi ts tightly into the opening. If a water drain
is fi tted in the bottom of the box, this must always be closed
during use to avoid cold air from running out and warm damp
air entering.
Electrical system
An electrical system that is both correctly dimensioned and in
good working order is required. This is especially important if
the refrigeration system is to operate continuously for a few
days during warm weather and not have to start the engine for
charging.
Calculate the boats total power requirements. The engine
should always have a separate battery for starting. In addition
to the battery capacity required for other electrical equipment
on board, one additional battery 75-100 Ah will be suffi cient
for the refrigeration power supply.
In addition to increasing the amount of "standby" power
available on board, the extra service battery can also store
surplus power when the engine is generating this. Two
batteries can, of course, accept twice the amount of charge.
The alternator is normally not a limiting factor. All service
batteries shall be connected to a "battery bank" and must
have generously-dimensioned cables for both positive and
negative circuits if they are to receive full charging voltage
from the alternator.
Using the refrigerator
Power consumption is dependant to a large degree on how
the refrigerator is used.
Let refrigerated food remain inside the fridge as far as
possible and take them out only when required. Don't leave
them out of the fridge longer than absolutely necessary when
cooking or having your meal. Put them back as quickly as
possible. Avoid placing warm food in the fridge. If possible,
use an insulated thermal bag when carrying frozen or chilled
foodstuffs from home or the shop.
Let the engine run for a while extra when leaving or
approaching the harbour. The engine alternator will then
supply an extra boost of refrigeration energy just when
needed, i.e. immediately before non-power periods of sailing
or in harbour.
Refrigeration temperatures
The correct temperatures for storing sensitive foodstuffs such
as meat, fi sh, milk products etc, are as follows:
The correct way to store refrigerated food is to never allow
its temperature to exceed 6°C (43°F). Switching off the
refrigerator overnight is a false economy and from a hygienic
point in view it is not recommended.
Internal temperature of refrige-
rated food
10°C (50°F)
8°C (46°F)
6°C (43°F)
4°C (39°F)
1°C (34°F)
The correct way to store refrigerated food is to never allow
its temperature to exceed 6°C (43°F). Switching off the
refrigerator overnight is a false economy and from a hygienic
point in view it is not recommended.
Compressor unit – Fig. A
The Danfoss BD50F dual volt 12/24 V refrigeration
compressors are of the very latest design and produces
extremely high refrigeration energy while consuming very little
battery power. As it is driven by 3-phase alternating current, it
has an unbeatable starting ability and the speed and capacity
can be regulated. It is of the same totally hermetic design
as that of domestic refrigerators and has a long operating
lifetime, low noise level and is completely maintenance free.
The piston type compressor operates on a mixture of
refrigerant and oil. The compressor unit are to be mounted
horizontally but it will operate at a continuous angle of heel
up to 30° in all directions. Should this angle be exceeded, the
compressor will stop automatically. It will re-start automatically
when the angle has been reduced.
The compressor is integral with the water-cooled condenser,
which is equipped with a self priming water pump.The
compressor unit is delivered pre-fi lled with refrigerant and has
irreversible quick coupling connections on the ends of the
fl exible piping which connects it to the holding plate. These
couplings can be disconnected and re-connected should
either unit need re-positioning.
Duration after which food can
become unfi t for consumption
1 day or less
1-2 days
2-3 days
5 days
5-7 days