Isotherm SP Installation instructions
General
Isotherm SP is a sea water cooled refrigeration system for
sailing yachts and power boats. This unique system means
reduced power consumption and noise level. It has no fan
or pump. The sea water cooled skin fi tting/heat exchanger
replaces the air cooled condenser and cooling fan. The
heat is transferred directly to the surrounding water instead
of being circulated as hot air inside the boat.
Description
The special skin fi tting with its integrated condenser/heat
exchanger is mounted in the hull and is made of salt water
resistant brass with the heat exchanger coil in copper-nickel
alloy and replaces the existing skin fi tting for the sink drainage.
The connection pipes to the compressor have a length of 1
meter and are equipped with quick couplings. The couplings
can be opened and closed without loss of refrigerant. A fi lter
dryer is mounted approx. 20 cm (7¾”) above the skin fi tting
on the return pipe. A 1¼” ball valve should be mounted on
the skin fi tting.
Important! The hose between the sink and the ball valve shall be a minimum
of ø 38 mm (1½”). The skin fi tting is normally kept clean due to the constant
movement of the water and lack of sunlight. During sailing or motoring the
water will fl ash the fi tting and the heat exchanger coil rapidly, which will keep
it clean from marine growth. The skin fi tting shall be equipped with the zinc
anode on the outside and which is included in the delivery.
Operation
Always keep the ball valve open to ensure a satisfactory function.
If the ball valve is closed and the boat is in harbour, the fridge will operate at
a reduced cooling level.
During sailing or motoring the fridge will operate better but not to its full
potential with a closed valve. When the boat is on shore, the fridge system
will operate at a reduced level, in this case the ball valve must be kept open
to allow air ventilation through the hose and the sink.
Maintenance
When necessary clean the through hull fi tting, do not use sharp or hard tools, a brush will be enough. In a tropical
environment, cleaning of the fi tting has to be made more often. If necessary, the threaded bottom entrance
washer can be removed for better access to the heat exchanger coil.
Corrosion:
Galvanic corrosion can often take place on board when the boat is surrounded by salt water and
should be carefully checked. This type of corrosion takes place depending on various electrical potential between
different devices. When two different metals are placed under water and connected to each other, electricity will
start to run. To prevent metal damages on parts under water, sacrifi ced anodes made of zinc are installed. Zinc is
a less noble metal compared to other materials used and will therefore be sacrifi ced.
All Isotherm refrigeration units have the plus and minus power supply separated from all chassis parts. Isotherm
SP has a skin fi tting in direct contact with the sea water and has as standard a zinz anode. The brass in the fi tting
is dezincifi cation and salt water resistant as well as the Cu/Ni condenser pipes and the soldering silver. The zinc
anode on the fi tting shall be inspected regularly and replaced as soon as half or more of the zinc is used. If it
is affected to a high degree and not lasting more than one season or part of a season, the electrical system on
board must be carefully checked to fi nd the reason for the galvanic or stray-current corrosion.
Make sure that the refrigeration system is connected to the electrical system in such a way, it cannot be
connected to the shore grounding when shore power is connected.
It is recommended to use an insulation transformer in the shore power system, to always be sure, boat and shore
grounding is separated.
When the boat is equipped with a central bonding system, the SP skin fi tting shall be connected to this with a 6
mm² copper cable. On the skin fi tting, there is a M5 hole for this purpose.
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