Fridge kit suggestions please

I am very tempted by a water cooled unit. It's a lot more money though- maybe £750 rather than £500. And I won't be lifting out before I install so I can't fit the skin fitting.
I did read somewhere about putting the skin fitting in a water tank... which is certainly a thought... but I wonder if you then lose some of the benefits, as the heat still end up inside the boat.
 
I think that you are planning on sailing to tropical latitudes?
If so, many savvy cruisers here have 6" / 150 mm of wall thickness on their ice boxes, rather than 100 mm - and this does make a huge difference.
OK, it reduces your storage capacity a fair bit, but it should cool faster (all else being equal) so you just have to replenish the beer within a bit more frequently..... :)
Even if you just have 150 mm thickness in the base this should help.
 
We have Dometic CRX, not sure of the size 80l I think - nor relevant). It s very good and perfectly adequate for a week in isolation. However the thread is about living on board in warmer climates. We also have refrigeration system that can be used as a deep freeze - its a complete standalone system. It is a rectangular box with 150mm of insulation all round and is built into the space below the galley sole. The access is 'the floor' or galley sole. It actually fills the bilge space' side to side (cats are narrow hulls) but the bilges forward and aft still interconnect - we have pipes at the lowest point.

For a new installation, where do you have large enough space that you can house a box of a size you believe will be adequate around which you can arrange 100mm thick (or more) insulation. It does not have to be an obvious and wholly convenient space as you will only access once every 2-4 days. Ideally you want to vent the location for a compressor such that you can re-fresh the air. Maybe a transom locker?

We use the galley sole as a freezer - in the same way you use a freezer at home. It is for long term storage, no opening and shutting the door (or in our case - hatch). When we go on a long term cruise it is stocked tightly with pre-frozen food and food is removed every 2 or 3 days and transferred to the fridge (which reduces power required in the fridge). We fish on passage and catch primarily tuna but also Spanish Mackerel, Dolphine fish etc. As soon as we have eaten some space in the freezer we start to freeze our catch - this negates the need to visit a supermarket (of which there are not many, think none, where we go) and keeps the freezer full. So catch a fish, clean, fillet, freeze. Any spare space and we keep the fish heads, (as bait for our cray pot). I agree its not ideal as you have to get down on hands and knees to access and the door/hatch is quite heavy.

The basic philosophy is simple, keep the doors closed, if we have excess power, turn the temperatures of both units down and use the power to further cool the contents, keep both units full (even if its only gin :) ).

It does turn into a bit of a religion (a bit like anchoring and soft shackles :) ), saving power, minimising water usage and separately keeping the units cold - but you grow used to it (and it spins off (a little bit) back at home).

The freezer is a kit, compressor and cold plate. The air round the compressor is ducted + computer fans from the anchor locker to the compressor and exhausts into the engine bay - which vents out of each transom. We did not opt for seawater cooling (maybe wrongly) because seawater temperatures can be 35 deg, 24 hours (whereas air temps can get cooler at night)

I cannot tell you what the average daily power usage is - the data is on the boat.

Take care, stay safe

Jonathan
 
Don't forget that one option for sea water cooling is a heat exchanger that replaces the galley sink drain skin fitting - Isotherm SP unit. Ours works very well.
 
My galley sink drain is above the waterline. I don't really have the option of swapping out or fitting a new skin fitting before we start cruising.
I have changed seacocks between tides before, that was fun, incoming tide is an excellent motivator. But I no longer have anywhere handy to dry out and don't feel quite so brave these days.

Here's a general question: when choosing the size of evaporator and compressor, if you make it work harder (by fitting to a larger compartment) what happens to the efficiency? Surely it's just removing the same amount of heat as a bigger unit would be, so it should be using the same amount of energy- just spending more of the time running. But as a smaller unit it will use less power when running, so perhaps it works out the same. I can understand how this would shorten the lifespan of the unit of course.

Or is it more complicated than that. Bigger evaporator and radiator more efficient? I know it works that way for central heating, this is why UFH is more efficient than radiators, because the system can run at a lower temperature thanks to the greater area available for heat exchange.

I'm only asking all this because the GE80 fridge kit at £370 seems an absolute steal. And my budget is feeling the squeeze...
 
I'm no expert, can only tell you what we found. The BD35 we had previously (mounted under the badly insulated 170L box) was running almost continuously whereas the BD50F (located in cockpit locker) with large O ring, cycles and cools to lower temperature. I didn't fit the keel cooler because I didn't want to pay for another haul out, having just launched. Unlike the UK, drying out alongside and fitting between tides wasn't an option. You're likely going to find below decks temperatures over 30 degrees so don't base decision on UK performance.
 
contessaman said:
Don’t be put of seawater cooling for warm water sailing. That’s a dodgy argument. Water conducts heat 20-25 times better than air so even 30c water still far more efficient at taking the heat away even with a smaller temperature difference. plus the heat is not being transferred to your cabin.
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I think it depends on a lot on where you sail. If you sail in a climate that has high sea temperatures and high air temperatures the differences in efficiency are not significant assuming both air and water cooled installation are both installed well. The problem with air cooled is they can heat up the cabin just when you dont need it. The fan can be noisy at night if you sleep near the compressor. If the ventilation flow of cool air over the condenser coil is poor then the efficiency will be poor and therefore the run time will be extended.

If you have similar cabin and water temperatures and the air cooled condenser is efficient and well installed, neither air or water cooling is going to get condensing temperature below circa 31/32degC regardless of the thermal transfer efficiency of water.
Also bear in mind that the cintred bronze keel cooler of a water cooled fridge cannot be anti fouled. In my experience the barnacle growth can be quite severe unless you regularly scrub it and even then in my experience the cintred aspect of the cooler is lost by calcium build up.
I have had both systems and been happy with efficiency of both in the Caribbean, but you really do have to get the air cooled install spot on to maintain high efficiency. If your proposed installation wont achieve this then opt for water cooled if you have the money
 
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andygc said:
Don't forget that one option for sea water cooling is a heat exchanger that replaces the galley sink drain skin fitting - Isotherm SP unit. Ours works very well.
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Andy I use the same system, very pleased with it. How do you clean the coil? It's quite hard to access once installed. Do you use antifoul?
 
These complications sway me back towards air cooled... for which my wallet says thank you.
My compressor will have to go between the saloon and the heads. Noise won't be a problem. I hope to have air drawn in from the bilge and vented in to the heads, which itself is a fairly well vented space.
 
I still think seawater cooled is the more efficient system.

if You do go air cooled, it Does need some ventilation to work well but I wouldn’t worry about heating up the cabin Too much.

it’s simple physics. If your fridge takes at worse 6 amps and it’s running half the time. Average 3 amp draw at 12v is 36 watts of energy To ultimately end up as heat. You aren’t gonna make a difference to the cabin temperature with 36 watts.
put it another way. If you were trying to build a cabin heater that would run off 12v batteries and take 3amps everyone would laugh at you.

that mains fridge in my cockpit locker has a 6” gap at the back and under the deck and probably 10” either side. It’s a fairly big locker, but the fridge works and cycles as it would in a house and the cockpit locker does not get hot. Again, sticking a 40 watt light bulb in there wouldn’t warm it up noticeably.

sounds like the best system is the one you can afford and get fitted in time to cruise with it
 
If making a new fridge I would be looking at vacuum insulated panels. A friend replaced the fridge insulation on his boat with them plus some standard filler for the gaps and it dramatically reduced his power consumption.
 
bobgarrett said:
If making a new fridge I would be looking at vacuum insulated panels. A friend replaced the fridge insulation on his boat with them plus some standard filler for the gaps and it dramatically reduced his power consumption.
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Our fridge has 150mm of Kingstown insulation on the bottom and 100mm on the sides and top. Currently in the UK the fridge run time is 3mins run, 15mins off. It's set as little cool as the yogurt was frozen this morning. In the tropics the run time increase but it's still acceptable efficiency.
 
I still can't find an answer to how efficiency and size of evaporator/compressor correlate.
The locker I am converting is pretty big, and I have a lot of kingspan left over from building my house, so maybe I should just get a smaller fridge kit and pack in a ridiculous amount of insulation...
 
When we were specifying A/C for our bedrooms, we were advised to go with smaller to increase efficiency. I guess it's a similar thing. Doubt there's much in it though
 
TopBanana said:
When we were specifying A/C for our bedrooms, we were advised to go with smaller to increase efficiency. I guess it's a similar thing. Doubt there's much in it though
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Interesting. That sounds a bit more like how you size a woodburning stove- peak efficiency comes at close to full output.
 
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