Isotherm TB 50 Installation And Operating Instructions Download Page 2

General

Specially designed to operate in tough marine environments, Isotherm 

fridges are outstanding in both performance and reliability. Fitted with 

a fully hermetic, leak-free compressor, they offer the lowest possible 

power consumption and noice level. All models are extremely simple to 

install. They can withstand an angle of heel up to 30°, for a short time 

even more. To ensure that your Isotherm fridge operates as efficiently 

as possible, please follow these general guidelines:

• Unnecessary opening of the fridge door will increase power  

  consumption.

• Good ventilation of the compressor and condenser unit will reduce 

  power consumption.

• The electrical system should be in good condition. Inspect batteries 

  and charging levels regularly. Always use a separate starter battery 

  for the engine. Follow carefully the guidelines regarding electrical

  cable areas and fuse placements.

• Keep the inside of the fridge clean and dry. Remove any water that

  may collect on the shelf under the freezer compartment.

• Keep the door/lid slightly open to air the fridge when leaving the boat

  for any length of time. (Fig. 1 and 2)

Operation

Refrigerators and boxes with standard thermostat.

See separate instructions for ASU versions.

Temperature setting

The fridges/boxes are fitted with a manually operated, infinitely-variable 

thermostat. This is turned clockwise to reduce temperature and anti-

clockwise to both increase temperature and activate the on-off switch 

at the end position. A certain spring resistance is recognized at the off 

position.

In most refrigerators, the thermostat knob is placed inside the 

refrigerator. The CR100 has the thermostat knob placed outside above 

the door. The build-in boxes and TB50 have the thermostat knob 

placed inside the refrigeration compartment.

The TB26 and 42 boxes have the thermostat regulation placed outside 

and also have separate on-off switches. The TB32 has an electronic 

thermostat, see separate instructions.

Defrosting

Defrosting shall be made when the frost layer is more than 4 mm thick. 

Set the thermostat in OFF position. Store the foodstuff and the liqued 

as cold as possible during the defrosting process. Do not use sharp 

metal tools to remove frost or ice. Do not re-start until the fridge/box 

is completely defrosted, cleaned and dried. Empty also the drip tray 

below the freezer compartment.

 

Maintenance

The Isotherm refrigeration systems have a fully hermetic closed cooling 

system and do not require any maintenance or refilling of refrigerant. 

The compressor is of domestic type and has a very high effiency and 

an outstanding life-time. The fridge/box shall be left in the boat during 

the winter. (If the temperature is below freezing point, the compressor 

may not start). The maintenance is reduced to periodically, not less 

than a year, cleaning of the condenser from dust. Use a soft brush 

and no sharp tools. Keep the fridge/box inside clean. Use lukewarm 

water and a mild detergent for cleaning the inside. Put the door/lid, 

during not in operation periods, in its slightly open ventilation position. 

Release the catch on the door for this purpose with a coin or a small 

screwdriver. Take out the bulb from the internal light to avoid power 

consumption or switch off a main switch if there is one installed 

connected to the fridge power supply. (Fig. 1 and 2)

Battery voltage sensor

To protect the batteries from becoming completely discharged, a 

battery voltage sensor switches off the compressor automatically at the 

following levels:

System voltage

Cut-out

Cut-in

12

9.6

10.9

24

21.3

22.7

Safety instructions

When connected to shore power, ensure that the power supply is 

equipped with an earth safety automatic switch.

 Danger!

Never tough bare electrical wiring connected to the mains supply.

 

Danger!

Never connect battery charger direct to the refrigeration system. 

Battery charger 

must

 be connected to the battery. 

In addition to acid, a newly-charged battery contains explosive gas. 

Danger!

Never cover the ventilation openings for the compressor unit.

Refrigerant may never be let out in the air.

Installation instructions

Many boats have a space which is intended for a fridge. The Isotherm 

Cruise fridge has been designed to suit the general dimensions 

normally used for this purpose.

 The compressor should normally stand upright in the boat, but will 

operate at an angle of heel up to 30° and for short periods even more. 

The compressor on CR42 and 50 as well as on the BI40 is attached by 

its rear side. It can be removed so that it can be mounted by the side, 

from above or from below and is supplied with 1.5 m flexible piping. 

The pipe must be carefully bended to avoid breaks or other damages. 

Installation can be made even simpler by using the mounting rails, that 

are available as accessories.

The CR49, 65 and 195 have three side mounting frame mounted as 

standard which simplify the fastening of the fidge. It should always 

stand on its feet and fastened from the front in the mounting frame. 

Three side mounting frames are also available as an option for other 

models.

Build in boxes has to be well fastened and should be supported 

underneath. The compressor on BI41, 75 and 92 is attached by its 

bottom. It can be removed so that it can be mounted by the side 

or elsewere and is supplied with flexible piping. The pipe must be 

carefully bended to avoid breaks or other damages.  

The fridge doors are hinged on the right hand side as standard. They 

can be re-hinged to the other side by taking off the door, moving the 

upper door hinge pin to the other side and also changing side of the 

lower door hinge pin fittings. The door locking is re-positoned to the 

other side of the door upper frame. It is fastened with three screws. 

See fig. 3 & 4.

Ventilation

It is very important that the compressor/condenser unit is well 

ventilated and that cold air can enter at the bottom, pass behind 

the fridge and warm air can leave at the top in the area where it is 

mounted. The natural flow of air from below and upwards behind 

the fridge can be increased by arranging ventilation openings at 

the rear.

  Fig. 1                                              Fig. 2

1

Fig. 3

Fig. 4

       

GB

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