Marine a/c in warm/hot seawater.

alk

alk

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I probably haven’t mentioned that I replaced our sailboat of past three seasons with a 1976 Viking double cabin - but anyways, first question on this boat.

i have two 16k cruisiar ”split” units - btw I love the splits, and hope I never have to go back to an all-in-one - having the noisy components in the engine room makes a huge difference. The units work well, and keep the boat nice and cool, even in middle of afternoon on 90+ degree days. But the water is heating up, hit 88 yesterday, and I’ve seen the Chesapeake bay bumping up towards 100 degrees by end of summer. Will the a/c’s still be able to cool us when the water is that hot? Or is there a limit at which point they lose effectiveness? Cant seem to find anything in the manuals, or online. Thanks!
 
Well the hotter the water the harder it gets. We re at 89 right now in Miami and it will get worst thru august.

The key thing is to make sure the sea water circuit is clear and that you get plenty of flow. It will help cooling but will also keep the compressor happy. Clean strainer, clean thru hull intake and a good pump are critical. I m a big fan of South Bay Strainers to keep stuff out

Also, annual cleaning of the condensing coils is important. It s pretty easy to do and saves you $$$. Just get a small bilge pump, the right hoses and a coupe of gallons of Barnacle Buster. Some people used Muriqtic acid but that nasty stuff. Shut down the system disconnect the hoses and circulate the BB for 45 to 60’. If you re not sure when it was last done, do it asap.

Splits are nice but can be a more maintenance intensive because of the piping Sadly newer units aren’t as reliable as the older stuff. Depends on the brands of course, cruisair is getting ridiculously expensive considering the quality.

In fact many owners are switching from splits to self contains as the newer units have gotten quieter.

I got rid of my 5 splits a few years ago and went with a chiller system. Huge improvement in reliability but not a cheap conversion …

One last thing… sea water pumps. If have a bronze head pump beware that the head and the impeller erodes with time and they loose capacity. The best pumps are march with magnetic drive.
 
Thanks, and good point on the pump hardware. My pump has a plastic hard, but coming off that, I guess it would be best described as a manifold, where the outlet from the pump splits off to the two units - is not in great shape, bad enough that I’ve been turning the ac off and closing the thru hull when I’m not on the boat.
 
You need to make sure the manifold isn’t made of brass… I ve seen it. Nylon fittings are the best for this use.

Sometimes people use bronze fittings like Tees and barbs but because bronze male nipples are very hard to find they use brass. It will corrode and fail in months. I ve seen air con pros making that mistake…
 
How many home air conditioners work just fine in 100 degree heat while being baked by a blazing sun. Happens with MANY millions of homes everyday. Does it really matter whether the AC unit is air cooled vs. water cooled?
 
cwms said:
How many home air conditioners work just fine in 100 degree heat while being baked by a blazing sun. Happens with MANY millions of homes everyday. Does it really matter whether the AC unit is air cooled vs. water cooled?
Click to expand...
It shouldn’t but air cooled doesn’t have the growth you get with salt water cooled unit. Keeping them clean is critical

I am using wireless temp sensors on each individual coil to measure their temp so I can back flush them before they get too hot and trip. This morning I back flushed one of our chillers and pulled about 1/4 cup of small shells that were reducing flow.
 
I know that the west marine selector is not the end all authority on marine A/C, but this page implies 95 degree water is pushing it.

https://www.westmarine.com/west-advisor/Selecting-Air-Conditioning-for-Your-Boat.html

and I've seen some other product specs that draw the line at 90 degree water.

 
I know this is an old thread, but question I had - is barnacle buster just diluted muriatic acid? it’s like 40 bucks a gallon ( damn Biden! 😀 ) or about ten times the price of the acid. Can I just use acid instead, as long as i dilute it down to 2%? This would be to flush my a/c units, and raw water side of my motors. thanks!
 
I usually buy the concentrated BB which used to be $27 pre Biden and is now $39… the concentrated BB dilutes 4:1

It’s different from muriatic acid. BB is much more user friendly and also easier on the hardware. Haven’t used acid in years, even diluted it s nasty stuff.

It works really well. I circulate it for 30-45 minutes twice a year.
 
Curious, where in the Chesapeake does the water get to be 100°?
 
hottest I have ever seen in the bay was 97 degrees, at the mouth of the sassafras river. That was 5 or 6 years ago. I heard weather predictions that it was going to break that last summer, but not sure if it ever did. Highest temp I recall seeing in the bay last July was 88. Up the rivers and creeks where the marinas are, it’s usually a few degrees warmer. I’m on Worton Creek. Around low tide on a 100 degree day the water in my slip is 5-10 degrees above the bay temp. Surprisingly, the day my temp gauge showed 97 in the bay, the water was a few degrees cooler at the marina.
 
Yup, I’m in Havre de Grace, and there were a few times in late summer my A/C just couldn’t keep up.
 
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