Refrigeration

[jon]

I am researching refrigeration units prior to building in a refrigerator/freezer top loading box into my boat building project.
It has to be efficient in terms of cooling and current consumption and also quiet.
The Isotherm ASU seems to be tops for current consumption with its feature of sensing when the engine is running and going on to high power. With the self pumping sea-water cooling option it would be efficient and quiet.
I would be grateful for any comments,tips, suppliers names etc for the compressor and also the box.


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[MedMan]

I suggest you contact Penguin Marine Refrigeration. They are specialists and extremely knowledgable and helpful.

Click <A target="_blank" HREF=http://www.yachtretreat.com>http://www.yachtretreat.com

 

[tillergirl]

I made a mistake building my fridge box in that I used relatively ordinary insulation. There are however, some very high spec materials available to the building industry for example selatex (phonetic) which would have been better. Used a Waeco unit - very effective but I only use it with engine on or plugged into shore power because of the power supply I have. Is very good, but I note it works hard after stopping the engine after heavy use, when I get quite a heat sink into the part of the bilge where the compressor is situated. Not much I can do about it as I had only one spot to put the compressor but if you have a choice a bit of distance would help.

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[colin_jones]

Jon

Have a look at Waeco and especially at their low consumption compressor and Mobitronic control system with a 'hold over' plate which chills right down when the engine is runing and then gradually releases its coldness over the next 8 hours - so saving lots of battery drain. It also acts as a small freezer cabinet.

If you are going for keel cooling, remember that when you are in -say- The Med, you mostly need the fridge when the weather is very hot and this coincides with periods of no wind and no boat movement, so a system needing movement to operate, becomes u/s.

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[gosh]

Can thoroughly recommend the pumped sea water cooling. It means no heat discharged into the boat which is important in hot weather.
One mistake I made. The cooling water discharge was about 6" above the water line which woke the crew up at night and caused complaints from neighbouring boats.
The pump supplied was too big and by reducing the flow the discharge noise was reduced without any loss of cooling.

Hope that helps

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[wpsalm]

If possible avoid the following ....seawater cooling, engine driven compressors , holding plates....recomend a simple 12volt compressor which will draw 4 to 6 amps the system I,ve used and found most effective,plastic bottles of frozen water in the freezer compartment these will be your holding plates...the best condenser is a coil of copper tubing at the bottom of your fresh water tank, no pumps required for this as it runs directly from the evaporator to the compressor...cheap simple and effective...

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[ChrisE]

I have one of the Isotherm units and it has given me trouble-free use since installation in 1996. Our is in a toploading coolbox and uses sea water cooling via two separate skin fittings for in and out, altohugh I understand that the later units can use the sink waste water pipe for both functions. We used for a year's sailing in the Tropics and other than having to clean the cooling water filter once, it has never needed any maintenance.

We found that the daily battery charge the engine run of about an hour a day would freeze the plate down and that was sufficient to keep the beer (and other non-essentials, like food) cold for the remaining 24 hrs.

Regarding the amount of lagging you need around the coolbox, Nigel Calder (he of boat fridge and freezer book fame) recommends 4" min for a 'fridge and 6" min for freezing. We have between 4 and 6 (our's fits in an irregular shape) and next to the cooling plate we can freeze icecubes, even in water temps of 28deg+ and air temps in 30s.

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[pvb]

Self-pumping seawater cooling...

If you're thinking of the Isotherm fitting which replaces the sink outlet seacock, I seem to recall reading about durability problems with this. As it's a haul-out job to repair, it might be worth investigating.

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[jon]

Re: Self-pumping seawater cooling...

Yes I was considering the self pumping sink outlet, it does have an anode, perhaps earlier units did not?
Any further info on this matter would be very useful!


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[pvb]

Re: Self-pumping seawater cooling...

I think earlier units only offered an anode as an optional extra. With this sort of fitting, you need to be very cautious about galvanic corrosion. If you're thinking of using shore power frequently, you'll certainly need to fit a galvanic isolator.

Another consideration is where you're going to be sailing. The Isotherm SP self-pumping system is very clever, but in northern European waters you'd only save about 15% on power consumption compared to an air-cooled unit. So, on balance, you might be better putting the cost of the SP into better insulation or enhanced battery capacity.

If you haven't seen it, take a look at the <A target="_blank" HREF=http://www.glacierbay.com>Glacier Bay website</A>. If you click on the "Library" tab, there's a good selection of useful information on construction and insulation of boat fridges. Glacier Bay tend to be regarded as the Rolls-Royce of refrigeration in the US.

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[jon]

Re: Self-pumping seawater cooling...

Thanks for that, I shall not be using shore power much, I have found a useful site as follows:
http://www.e-marine-inc.com/products/refrigeration/faq.html

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[roger]

I used a Waeco unit and have found it OK. Since it ias fan cooled into the boat the fan (not the compressor) noise is appreciable during the night. I had no choice as to where to site the compressor. The fridge has worked fine.
Materials. Builders merchants sell a 35mm. Aluminium faced polyurethane insulating board. It is allegedly the equivalent of 50 mm. of polystyrene foam. I made the liner out of the expanded PVC material that is used for replacement baarge boards for house upgrading. It has a gloss surface one side. It is not particularly strong but the loads inside a fridge are usually low. It adds a bit to the insulation and is about 12mm. thick. The suppliers provide a cyano acrylate glue specifically for this material and it works well.
You will appreciate that the interior is rather small compared with the outside as the walls have to be thick to get a reasonable heat load.
I bought sealing strip for the door from Seals Direct.
I found the final joining up process between the compressor and evaporator fairly traumatic. You only get one attempt. If you try and separate the pieces all the refrigerant escapes. No it didnt to me but I worried about it a lot.

<hr width=100% size=1>Roger

 

[Avalon]

A cheap solution

Before I set off for the Caribbean I agonised about whether to get a fridge or not as they are outrageously expensive and use loads of power.

For £50 I bought, secondhand, a Camping Gaz Groenland CTL175 fridge which I suppose is designed for camper vans and the like. It will work off mains electricity, 12 volts or Gas. The 12 volt option is useless. Works fine off 240V or gas - a standard Camping Gaz cylinder lasts 2-3 weeks (and gas is cheap out here).

Disadvantages - will not work when boat is heeled and does give off some heat, so need to be properly vented.

But it was cheap and has worked without a hiccup for 10 years.

So here I am in Trinidad drinking a nice cold beer.

Cheers, all....



<hr width=100% size=1>Phaon Reid, S/Y Avalon of Arne
www.sailingontheweb.com

 

[ChrisE]

How\'s the carnival?

Phaon,
Nice to see that you are still alive and kicking!
Chris

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[jon]

Re: A cheap solution

Thanks for that, trouble is my sailing mate has only just got used to sailing with me with a gas cooker (he calls it a bomb). If I fit a gas fridge I'll be sailing on my own.
I have decided on the smallest Isotherm build in box with ASU air cooled unit plus 80mm of extra polyurethane foam.
Thank you every one for the advice.

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[pvb]

Good choice...

While you're at it, had you thought of building in a red LED light (or similar) for night illumination? Makes it much easier to find stuff on night watches.

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[jzaat]

Re: A cheap solution

I have the ASU isotherm for 3 years now and hasn't failed me once!
Use the seawater cooled variant in te med and no problems. I use the water in the watertank for the cooling, saves on extra holes in the boat and all this galvanic problems!




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