Friday, 27 March 2015


Genesis probably, like most other yachts of this size, was equipped with an insulated "cooler box" set into the galley counter top. Initially we filled this with ice from the local supermarket to keep supplies (beer and Prosecco etc.) cold but quickly found that ice was competing for booze space!

This led to the idea of looking for a fridge unit that we could retrofit to the cooler box to give us a proper fridge. Many DIY fridge units are available from the major chandlers that, can be fitted without the need to hire a refrigeration engineer. Isotherm & Waeco seem to be the most popular/available brands, with units to suit most box sizes.

Installation is simple: select the condensing unit & evaporator plate combination that suits your cooler box size best (always go bigger in terms of capacity). Evaporator plates are available in a variety of sizes and shapes and can be easily bent to fit a non-standard shaped box. This is exactly what we did. The cooler box was roughly 34 litres in capacity, so we bought the smallest flat plate evaporator and bent it into an "L shape" to fit along the side of the box. Once you've found a suitable location for the condensing unit (compressor etc), then all that is required is to connect the evaporator plate to the condensing unit via the quick couple connectors (simple spanner connection), power up the unit and bingo!

Most models of condensing unit use an air cooled condenser similar to your domestic fridge at home. Tucked away under a bunk or in a locker, the warm air from the compressor has nowhere to escape and will warm up the locker/interior of the boat.  Not a problem in winter, but it's the last thing you want in summer! Furthermore, the compressor will run for longer ratcheting up electricity consumption.

Having a background in refrigeration, this concerned me, given the small size of our boat. Keel cooled condensers are a better but more expensive option, however I discovered a rather interesting solution offered by Isotherm. Isotherm produce what they call a "self pumping" unit; essentially a water cooled condenser which doubles as a through-hull fitting for the galley sink drain. Slightly more expensive than ordinary air cooled condensers but way more efficient. The "skin fitting" or condensing coil replaces the galley sink skin fitting (you simply drill out the old one and fit the new one). The refrigerant pipes connect to this via the quick couple connectors and it's ready to fire up.An added benefit is that it takes the standard sink drain from 1/2" to 1 1/4" so no more blocked sink drains!

We've had it operational all Summer and I must admit how impressed I am with the operation. Power consumption is also quite low, at less than 10KWh per week in the marina (never switched off), and it never runs the domestic battery (a single 100Ah) particularly low whilst at anchor. This would probably improve significantly if the cooler box was better insulated than the paltry 1" of foam it currently has.

All in all, one of the best upgrades we've done.

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