Water Cooled Refrigeration

[Martin S]

What's your experience of using water cooled condensers. I am considering the ISOTHERM range. Currently I have an aircooled condenser it seems very inefficient and has the additional problem warms up the already warm cabin.
Replacing looks reasonably straight forward. I'd love to hear from otehrs who have tackled this. Thanks...

[ColdEH]

Water cooling , more trouble then it's worth. Air should be good ! Where are you cruising? Are you ventilating the condenser away from the compressor area.? If not this could be your problem.

Water cooling adds a lot of complexity and potential pump / corrosion and added power consumption of running it .

Go to Kollman Marine it is well explained on Richards website .

Regards

[a64pilot]

General consensus is water cooling is not worth the hassle, corrosion etc.
One person actually calculated the heat gain from an air cooled typical condenser, and it was equal to having 1/2 an extra person in the room, so heat gain isn't nearly what you think it is.
My reefer is oversized, and it pull 5 amps, 5 amps at 13 VDC is 65 watts, so if it converts power at 100% efficiency to heat, then it is the same as having a 60 W light bulb in the room, but I have an oversized system

[Cheechako]

I've had both. Not convinced watercooled was any different and more to go wrong.

[skipmac]

I have a 9-10 cu ft box which contains about 1.5 cu ft freezer section. I have an air cooled BD50 compressor that I install under the floor in the main cabin. In Florida mid summer, day time temps in the mid nineties I was using about 45-50 amp hours/day. Winter when temps are in the 50-60 range the consumption is half that. I did rebuild the box and have min 4" insulation all around, 8" on the bottom and against the hull and a really good seal on the lid.

I also tested how much heat that added by covering all the large holes from the floor into the main cabin and letting the fridge run for a couple of days. Stuck a thermometer in the compressor area and it was just a few degrees warmer than the main cabin. If I had ventilated that heat into the main cabin I think even the slightest air flow from the hatches would dissipate any heat produced.

[Lepke]

Common in ships. Water transfers heat much better than air. Mostly used in ship wide AC, large refers, etc. Commercial fishermen use it in fish hold refrigeration.

[wrwakefield]

Originally Posted by Martin S

What's your experience of using water cooled condensers. I am considering the ISOTHERM range. Currently I have an aircooled condenser it seems very inefficient and has the additional problem warms up the already warm cabin.
Replacing looks reasonably straight forward. I'd love to hear from otehrs who have tackled this. Thanks...

Hi Martin,

The previous owner of our boat spent 15 years in the Bahamas and S America.

They replaced the main refrigerator compressor set-up to one with both fan and optional water cooling.

They installed the water recirculation pump with an on/off switch and separate hour meter, and plumbed it to one of the 2 potable water tanks to eliminate raw water cooling concerns. [The boat has 2- 110 gallon water tanks and a water maker.]

Since that compressor can be air or water cooled, and each have a separate hour meter, it was easy to quantify the efficiency gains comparing run times of water vs. air cooled [30+% based upon 2 years of data in the same region where Cooling Degree Days in the warm seasons average mid 3 figures. i.e., the higher the number, the more cooling needed to reach your desired cabin temperature. Likewise re: heating for Heating Degree Days...]

Note that the boat is also air conditioned, but that was only as needed unlike the 24/7 refrigeration demand...

Since we are in cooler climates with that boat now, I have experimented with turning on the water cooling that same system. It does reduce the run-time somewhat [4-10% on average depending; more on sunny summer days, and also in winter when we are heating the boat full time...] but perhaps not significantly enough to justify it if I was starting from scratch and planning to stay in cooler climates. That would of course change if/when we take the boat to warmer regions.

Otherwise, given how happy we are with the efficiency of our Engel freezer, I also wouldn't hesitate to install an retrofit Engel compressor in our ice box...

One last thought, depending upon the compressor you currently have, it might also be worth evaluating adding one of these newer [and intriguing] compressor optimizing devices.


Best wishes with your project.

Cheers!

Bill

[leftbrainstuff]

Originally Posted by Martin S

What's your experience of using water cooled condensers. I am considering the ISOTHERM range. Currently I have an aircooled condenser it seems very inefficient and has the additional problem warms up the already warm cabin.
Replacing looks reasonably straight forward. I'd love to hear from otehrs who have tackled this. Thanks...

We have keel cooled fridge and freezer. Frigoboat.

Keel cooled is much more efficient above 90 deg F. Much quieter too.

If course you must install the keel cooler which requires a haulout.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[cruisersfarm]

Anything on the whole boat you can do without a seacock os the best way to go. Period.

[zboss]

As I understand it water cooled systems are old technology.

We are installing a keel and air cooled frigoboat system this week. The keel cooler is the actual condenser so you do not need water cooling. The installer we are using is installing a switch on the condenser fan so we can turn it off when in the water to save power. On the hard we can turn the fan back on to keep the fridge working.

There is no seacock... only the bronze keel condenser with the tubes going in though the middle. Since the system is connected to power, we plan on binding the keel condenser to the zinc binding system.

FYI, bigger boats are now being fitted with keel cooler for the engines so there is no raw water being pumped!

[nhschneider]

We have had water cooled refrigeration on our boat since we bought it 20 years ago but we're going to switch to air cooled by the end of this month. Two main motivating factors:

1. We are uncomfortable leaving the boat for an extended amount of time with the refrigerator left on for fear of sucking a plastic bag or other such garbage into the water intake. Every time we want to do some land travel, we wind up giving away hundreds of dollars worth of food.

2. With water cooled refrigeration, it becomes inoperable once the boat is hauled out. We're tired of having to lug bags of ice up a ladder in the tropics to cool down a few beers and a liter of milk.

The refrigeration guy we met with today says we won't notice the increase in cabin temperatures by using air cooling. That remains to be seen.

Fair winds and calm seas.

[zboss]

Originally Posted by nhschneider

2. With water cooled refrigeration, it becomes inoperable once the boat is hauled out.

The Frigoboat is a keel cooled with an optional air cooling. Nothing gets sucked into the boat and when you are on the hard the air cooling takes over.

[SVNeko]

We have 3 of the isotherm keel cooled units. They are not water cooled in the traditional sense, but rather send the heated refrigerant through a coil in a large through hull fitting. They work very well, even in warm water, and do not heat the cabin. They are designed to be used as a drain, but ours are capped off permanently. So they might be a bit less efficient because there is not as much water sloshing up and down. Have had compressors die but no issue with the refrigerant loop.

[a64pilot]

Originally Posted by nhschneider

The refrigeration guy we met with today says we won't notice the increase in cabin temperatures by using air cooling. That remains to be seen.

Fair winds and calm seas.

I think it may have been Gord that did the math on heat gain, and came up on average the heat gain amounts to the same as having 1/2 a person in the room with you, it's not much when you think of it that way.

[aluijten]

Depending on your needs there may be a middle way. Our boat has a condenser shaped as a coil integrated in the hull fitting used for the sink drain. So no additional holes in the boat. Because the coil sits in the water, no additional pump is required.
For moderate climates this works quite well. It not advised for tropical waters although ti will work as well. Compared to air cooling it saves about 20% energy.
The system is sold by Isotherm and most often in combination with a ASU unit, basically a cold accumulator.