Frig installation

[LORDNELSON]

I have space for a 75 litre frig. Sailing boat, engine normally used to go in and out of harbour (say three-quarters of an hour each time);plan to instal two 50 watt solar panels. Boat is kept at swinging moorings without access to shore electricity. Normal cruising area is the Channel, Brittany Coast, southern North Sea, usually cruise the boat for two months in the summer and short trips (2 to 3 days) in the Solent for the rest of the sailing season. Have collected lots of details at the Boat Show. Would be grateful for any advice about type of unit, type of cooling and likely problems.

 

[vyv_cox]

Electrical: I currently have a 55 litre frig and a 36 Watt solar panel. Cruising Holland and North Sea. Running the engine rather less than your estimate, the batteries just about cope with all electrical demands, but we are in the strong position that most marina electricity comes with berthing fees, so we run the frig on the mains whenever we don't anchor overnight. Based on our experience I suspect that your 100 Watts will cope easily.

Cooling: Ours is air cooled but it struggles in the heat of summer, which does happen here in Holland. We are now looking at uprating to a larger frig (75 litre) and adding a cold plate to the cool box, the whole lot to be driven by a Danfoss water cooled compressor. This in preparation for our intended transfer to warmer climes, 2004. I am struggling to find a frig in this size that is driven by an external compressor, as all I really want is the box. I hope to be able to install another cold plate in that.

Easiest way around the cooling seems to go for an Isotherm condenser unit, but these are very expensive and my son tells me they corrode galvanically.

In your case, with no other electrical source, I would seriously consider an engine driven compressor and cold plate. Sunsail use these on flotilla boats and the arrangement works very well. A little motoring morning and evening keeps ice on the plate for most of the day. For us it seems a pity not to use the free marina electricity.

Would be grateful to know of a supplier of a 75 or 80 litre frig without compressor.

 

[HenryB]

IMHO insulation is the most important part of any fridge installation. I run an old Danfoss air cooled unit which draws just over 4 amps.
Last year in the Aegean it was running for 60% of the time, that's about 60 amp hours per day. I rebuilt the fridge compartment last winter using the best reasonably priced insulation that I could find - Celotex PIR foam insulation board. This is available from some builders merchants. It's foil faced and has an R factor of 7 to 8 per inch thickness. Try to get the insulation at least 5 inches thick at the bottom, 4 inches around the sides and 3 inches at the top. My unit now runs for about 25% of the time (in summer in Turkey) and thus draws about 25 amp hours per day.

I have a 60 watt solar panel which I estimate gives about 35 amp hours per day in summer. The odd thing about solar panels is that they are less efficient when they get hot - remember that they use light not heat to generate electricity.

I also have a 30 watt solar panel and can maintain the batteries for extended periods without running the engine. (That's with just two of us aboard, when my beer drinking friends arrive the consumption of both cold beer and electricity goes up alarmingly).

I use 2 computer fans for cooling.

Hope this helps,