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Armchair Sailor 09-07-2012 05:35 AM

Water Cooled Air Conditioners For Sailboats?
I was reading an interesting thread about types of useful air conditioners for boats in the summer heat sailnet. com/forums/general-discussion-sailing-related/89598-no-c-when-motoring.html

There was no mention of using (naturally) water cooling for sailboat air conditioners. Does anyone have any experience with water cooled air conditioners on boats?

theartfuldodger 09-07-2012 05:52 AM

Re: Water Cooled Air Conditioners For Sailboats?
I'm not sure what you have been reading but any airconditioning unit on sail boats I've seen are all water cooled.

Minnewaska 09-07-2012 06:25 AM

Re: Water Cooled Air Conditioners For Sailboats?
My marine air systems units are raw water cooled.

misfits 09-07-2012 06:44 AM

Re: Water Cooled Air Conditioners For Sailboats?
I think armchair sailor was curious about using raw water for cooling in lieu of a compressor/evaporator coil that uses freon.

There was a discussion on this subject over the summer. Some folks say they have used or have know someone that uses "yankee" air conditioning. Typical ac units have a discharge air temperature of 55-60 degrees @ 95 degree outdoor temperature up here in New England.

Bottom line, if the water is cold enough you can condition the air with raw water, but as the water temperture rises, the a/c discharge air temp also rises.

Minnewaska 09-07-2012 06:54 AM

Re: Water Cooled Air Conditioners For Sailboats?
Shallow water temps easily get up into the 70s in Southern New England, which would do nearly nothing if just run through coils to heat exchange with the air. However, Armchair lists their location as Cal, which may be California? I believe water temps are cooler there, although, maybe not in shallow water.

Still, I would sooner install a bunch of 12v fans around the boat than spend the money on raw water to air heat exchanger.

TakeFive 09-07-2012 09:11 AM

Re: Water Cooled Air Conditioners For Sailboats?
Raw water reverse cycle A/C is pretty standard. In cold water areas it's possible that you might get enough cooling just from the raw water without a refrigerant compressor to remove the heat.

The Delaware River peaks at around 85 degrees mid-summer, which even makes it difficult for reverse-cycle air conditioners to keep up. The guy who used to have his boat two slips up from me figured out a clever workaround: he hooked up the marina's fresh water system to the intake of his reverse cycle system. Then the marina got the $3000 water bill and went looking for where all the water was going. That's why he no longer has his boat there - he got kicked out.

RichH 09-07-2012 10:47 AM

Re: Water Cooled Air Conditioners For Sailboats?
The problem with raw water AC, in lieu of freon, etc. systems is the heat exchange cycle which normally requires a 15F 'approach temperature' - the resultant temperature of the max. cooling will only be 15 warmer than the inlet temperature of cooling water. eg.: If the inlet water is 70 degrees, the 'best' output from the AC will be 85.

Normal AC and refrigeration uses the expansion of pressurized/compressed gases which subcools the air and that takes 'energy' to so.

Barquito 09-07-2012 08:46 PM

Re: Water Cooled Air Conditioners For Sailboats?
Well, what about in a place like on Lake Michigan? The water probably doesn't get much warmer than mid 50's at about 30' depth. The summer temps get near 100. Is there some passive way (no electricity) of getting that cold water up to the boat?

Armchair Sailor 09-07-2012 09:46 PM

Re: Water Cooled Air Conditioners For Sailboats?
Thanks for all replies. I now found several vendors for water cooled marine air conditioners such as this marinaire. com/Marine_air_conditioner_p/msba6k2.htm
and this aquaair. net/SSIG_Self_Contained_Units__80706-11.pdf

They make smaller and more efficient units now. The prices for the smallest 5000 BTU units seem to be around $1500 after you include the water pump.

Frogwatch 09-07-2012 11:14 PM

Re: Water Cooled Air Conditioners For Sailboats?
Boat AC seems to use such crappy tech. Its the same old compressor/condensor as land based systems when boats have access to the worlds biggest heat sink. You'd think somebody would make an absorption/type of AC using the ocean as the heat sink
There are actually zeolite based AC systems for buildings where heat is used to remove the water from the zeolite. Normally, boats have access to almost unlimited sunlight too for heating it. Somebody needs to combine these into a good small marine AC.

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