Water Cooled Condenser Window Unit AC

[gwp]

I am surprised how little info is available on converting a window unit air conditioner to Marine use. Simply replacing the factory air condenser with a water source condenser (which fits on the factory condenser footprint), installing a circulation pump, some plumbing, and a thru hull, and you can have a ductless built in ac unit. The way i figure it, a 5000btu system could be done for around $300 including the ac unit. The only additional cost would be to have a shop evacuate, recharge and solder the condenser in place. A friend has used this system without problems for years. And....a bonus is that the efficiency of the ac unit is enhanced. Why has this not caught on? Feedback appreciated as I'm about to pull the trigger on this.....

[SeaBuffalo]

Well there are a lot of reasons. First a good cupronickel heat exchanger is going to be at least $200. Then there is the issue of calculating the new charge for the unit that will allow for proper superheat with the variations of the water temp used to cool the HX.

You could do it for a couple hundred by doing something like a tight coil of 1/4" copper in a vessel of 4" PVC with seawater running over it. But your going to have issues with corrosion and also setting a proper charge.

It can be done but just not much market for it. If I recall they did make a large water cooled suitcase style boat ac. Just plug in power and water and it would cool nicely.

[gwp]

This is the cupronickel condenser i plan to use which sells for $120.....
http://heatexchangers.doucetteindust...origin=keyword
Don't understand the charge issue related to water temp. How does a typical Marine ac system handle this issue? Thx!

[feltonmichael]

There is no charge issue with varying water temp, Everyone over complicates things I've been using a system just as you described for years no problems. Do it and save your self tons of money.

[SeaBuffalo]

Originally Posted by feltonmichael

There is no charge issue with varying water temp, Everyone over complicates things I've been using a system just as you described for years no problems. Do it and save your self tons of money.

Well it is a little more complex than just swapping the coil, vacuuming and charging. With just about all window ac units having a capillary tube they are charge critical. Too much refrigerant and you get liquid back to compressor and too little causes high super heat which means lack of performance, high discharge temp and shortened compressor life.

With reefer box it's easy to look for a frost line to guess on charge but not on a ac unit because coil runs above freezing. So you can charge on cool day and be short a charge on a hot day. There are plenty of marine ac units that use cap tubes so not saying it won't work just that getting the charge right is going to take a lot of patience and monitoring superheat with a good type k or similar thermocouple.

Or go down and buy a chatlef style flow-rator style housing and use it with a small TXV. Then your charge problems are gone and will work at maximum efficiency in all conditions. That's what I would do and would only add $30-50 to cost.

[djmarchand]

SeaBuffalo:

Could you please explain the terms you used in your last paragraph.

David

[Boatguy30]

I have seen one installed in the aft cabin of. 43' ketch. They guy that owned the boat was a retired AC tech. I would imagine it not too difficult, but the units are cheap enough if you make a mistake. could always but the heat ex on another unit.

[SeaBuffalo]

Originally Posted by djmarchand

SeaBuffalo:

Could you please explain the terms you used in your last paragraph.

David

A chattleff style housing is just a piece of tubing with a break in the middle where there is a nut and fitting sealed by a nylon washer. Easiest thing is just google chatleff distributor housing and when you see the picture you will understand.

They are normally used to hold a fixed metering piston which is the equivalent of a capillary tube. But you can remove the metering device from the Chatleff housing and install a expansion valve aka TXV.

[SeaBuffalo]

One thing to watch out for in window units with aluminum tubing. A lot of manufactures have gone to aluminum tubing for cost cutting and it takes flux and carful torching to make joints. Just a little too much heat and it melts with almost no warning.