Your thrill seeking reporters here, calling in from the swampland of coastal North Carolina, where, we are ever so pleased to report it is hot and sticky. All the better to test our newly installed and craftily re-plumbed air conditioning system. What could be better than 90F/29C with a caressing humidity of 70%.
Wind Horse has been patiently stabled at Cory and Angela McMahon’s Triton Marine in Beaufort. She is high and dry, quite clean on the outside courtesy of tropical storm Beryl and a five inch/120mm downpour the day preceding our joyful reunion.
Coming from the dry heat of the Sonoran Desert the humidity would be untenable hauled out like this, but we are happy to report that the air conditioning system is working with us out of the water. A few details for those of you into BTUs.
We have a pair of 16,000 BTU Marine Air units in the great room, a 10,000 BTU system for the aft cabins, and a 12,000 BTU unit forward. The air conditioner condenser coils that would normally be cooled with sea water are in fact plumbed into the aft fresh water tank. It is full at the moment, holding roughly 700 US gallons/2700 liters. Yesterday at 1700, the worst of the day, with all four units running temperature at the water return point was 104 degrees F, and 10 degrees F less after having gone through the tank. This after running for the preceding eight hours.
As the air conditioners were cycling on and off, their full output not being required, we decided to really hammer the system and dropped all four units’ program temperature ten degrees F. This had the effect of keeping all four units on 100% of the time. The temperature of the fresh water tank rose over the next two hours until water temperature returning to the tank was 116F, at which time the various compressors started to shut down with their high pressure cut outs. Today with the system backed off to 80 degrees F/24C the tank has remained cool enough to keep everyone happy.
As water is far more efficient at heat transfer than air, once we are afloat the system will work even better.
We are into an intense week of boat projects with Cory and crew, so we’ll hold the gory details until we are afloat, or at least get a break, after which we shall resume testing of various items on our half scale model of the Wicked FPB 97.
Posted by Steve Dashew (June 1, 2012)
June 2nd, 2012 at 2:14 pm
Hi Steve,
What’s the chance of the A/C eutenic fluid leaking into the water tanks? And if so what are the associated health hazards?
June 3rd, 2012 at 9:28 pm
We are simply circulating fresh water through the condensers, so no eutectic solution is involved.
June 2nd, 2012 at 4:51 pm
Hello Steve,
Are the fresh water you are using for drinking water? The temperatures you are providing at around 100deg F are perfect for breeding legionella and what you are doing would be considered very high risk, if not illegal, in building design.
Here is a link to some information for you to consider.
http://www.osha.gov/dts/osta/otm/legionnaires/faq.html
June 3rd, 2012 at 12:32 pm
Good news indeed. Our own haul out of our trawler in Panama earlier this year comes to mind, where we had 90 and 90 in terms of temp and humidity. Couple that with a lack of breeze, and the tendency not to open the boat up much anyway in the dirty environment of a busy boat yard, and you have a recipe for a couple of sopping wet, miserable owners. I know there are several advantages to your closed system design, but the benefit of being able to cool down even a single zone when on the hard… that’s huge. Even afloat, working in the engine room in the tropics is a challenge. Which is why we are have decided on air conditioning in the engine room of 64-7.
June 3rd, 2012 at 1:57 pm
I know you’re committed on Windhorse with your existing system, but have you considered trying a mini-split unit on a boat? No ducting, small plumbing chases, extremely quiet inside and outside units, heating and cooling via heat pump.
Bill
June 3rd, 2012 at 9:38 pm
Hi Bill: Please give us more details on the mini-split unit to which you refer. If there is something better we would like to know about it.
June 4th, 2012 at 6:37 am
Steve,
Here’s a description of the principle…….www.mini-split.com
Here’s a typical Mitasubishi unit with pricing…..http://www.acwholesalers.com/Ductless_Mini_Split_Heat_Pumps_s/430.htm
Bill
June 4th, 2012 at 2:45 pm
Sorry for the LG link, here’s some Mitsubishi units http://tinyurl.com/72wr4sa
June 3rd, 2012 at 6:19 pm
I’m concerned about the potential effects of differential heating on the hull paint. Since you are still high and dry, you might take some macro photos of the external area at the joins of the tank with the rest of the hull. Since you have super paint that shrugs years of wear, it probably can take this stress in stride, but the proof might be useful to future skeptical customers and other inspectors.
June 3rd, 2012 at 9:40 pm
The heating issues are more pronounced on the FPB 64s in the area of the hull coolers for the hydraulic system. There have been no reported problems with paint as far as we know.
June 3rd, 2012 at 7:33 pm
Love the idea of eliminating the SW from inside the boat. Curious, though, about the effect on potability of the fresh water – did you do anything special to clean or sterilize the SW cicuits of the HVAC units? Had they previously been SW cooled?
June 3rd, 2012 at 9:42 pm
See several other comments, Chris. Bottom line, we treat the aft tank with eight passes through the ultra violet sterilizer.
June 5th, 2012 at 9:15 pm
Hi Steve,
I have a 43 foot trawler and put two mini split air conditioners that I bought in Mexico on the boat. They don’t care whether you are on the hard or in the water and I leave one on when I leave the boat in the water as no sea water is being pumped through the boat. One 8000 BTU unit in the salon and one in the master cabin. I wanted 120V units as the power in the boat yard was VERY marginal. Not an excessive capability but we’ve been comfortable for 2 years near Cancun and now in FL. I chose the Haier brand as shape of the out side unit would fit inside my fly bridge. They draw air through louvers near the helm and the hot air exits through custom built louvers out the side. The one for the salon is too close to the entrance door and unless you duck a shot of hot air musses your hair when using the door. The indoor units are a little bulky but amazingly quiet. I bought the boat as a “fixer upper” and spent the first summer on the hard on Isla Mujeres and bought the mini splits out of desperation. $320 each plus the ducting I had to build. The ss louvers cost almost as much as the air conditioners them selves. I thought that the outdoor units would rust out in a year or two and at $320 each time I could replace them with little heart burn. But two and a half years later they still look good. I did spray them down with some stuff that was recommended by a guy who maintains ac units for motels on the beach. If you want some pictures I will try to send some to you although the boat is still a “work in progress”.
Regards,
Daryl
November 28th, 2012 at 11:28 am
Daryl,
I am looking for a solution for hvac without using seawater, and your description of your setup sounds very similar to what I had envisioned for my situation. I like the idea of using a split system, and I have the perfect place to position the inside part of the split. However, I’d need to put the outside compressor inside the flybridge cowling and I was trying to figure out if it’s possible to ventilate the enclosed area (behind the instrument panel) sufficient to shed the heat from the compressor. Could I impose upon you for pictures of the louvers you’ve installed? polpaulgm@gmail.com
Steve, your configuration is very innovative. Unfortunately, my water tankage is only around 150 gals, so I doubt I have the capacity to shed enough heat for my purposes using your solution.
June 5th, 2012 at 9:17 pm
Sorry, typo. They are 9000 btu units.
Daryl
June 23rd, 2012 at 5:36 pm
Hey Daryl- give write me your contact info at bill@bondassociates.org.