Installing a Replacement Refigeration System

Jul 13, 2018 | Technical

Having an installed freezer chest, that no longer operates, can bring tears to your eyes if the beer is warm and the air temperature hot.  Our faulty freezer was diagnosed with a leak in the refrigerant-gas piping, buried well within the cold-chest … an expensive fault to fix requiring a complete rebuild of the built-in freezer chest.

After researching the alternatives we decided to convert from the engine-driven freezer system to a 12V battery powered refrigerator system with an evaporator cold-plate that could be installed within the existing built-in insulated frig-chest.  We thus purchased an Isotherm system (comprising electric compressor with quick-clip mounting bracket, cold-plate, and thermostat control) and did the installation ourselves.

The conversion was simple.  Initially I removed the old un-used and bulky engine-driven freezer compressor, condenser unit and associated pipe-work plus filter.  For the new system I decided to locate the small compressor unit under the quarter-berth next to the frig-chest.

The compressor unit mounted next to the battery

A hole was drilled through the frig-chest wall, for the frig-gas piping between compressor and cold-plate, and I then mounted the cold-plate within the frig-chest and laid out the piping.

The cold-plate mounted in the cold-chest

The compressor unit and thermostat control were then mounted, and the piping between compressor and cold-plate connected (releasing the pre-filled refrigerant gas into the cold-plate).  The 12V electric supply was set up, via the old freezer power-switch plus fuse, and with battery power on and thermostat control set the new refrigeration system started immediately.  A final tidy-up, sealing the frig-chest hole with expander foam, coiling / securing the excess frig-gas piping, gluing a small thermometer inside the frig-chest … and … job done.

Cost of the pack was $1,032.00 (Sept 2004) and the installation took about 6 hours.

After this first summer we are very happy with the results.  We pack pre-cooled and frozen food into the frig-chest for our weekends or times away. The frig power is switched on as we slip the mooring lines and its temp is down to approx 48C after about 4 hours … and there it stays.  We have two separate 12V batteries, one for engine cranking and one for boat-house use, so we keep power on to the frig continuously, and run the engine for half an hour daily to keep the house battery charged.

So … a frig just like at home with cold but not frozen food or beer .. and happy boaties.

Some technical details;

Cold-chest sizeApprox 45 litres

Fridge model / packIsotherm GE80

Pack CompressorDanfoss air-cooled

270L x 160W x 155H

Pack Evaporator  /  cold-plate350L x 250H x

approx 4 mm thick

Thermostat ControlOn / Off with temperature adjustment

Power specification12V x ave 0.6 Amp draw

Battery protectionAuto cut-out at 11.7 V

Compressor run-timeAutomatic  for approx

1 min every 10 minutes

System noiseNot noticeable even at night

Weight of system9 kgs (vs 20 kgs of the old removed system)