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Old 11-04-2014, 08:24 AM   #1
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Ductless AC systems

Has any one experience with these units? There are several models and makes. Mitsubishi has one that is $$$

http://tinyurl.com/k5ffukh

Seems like a option instead of pumping sea water.

Thanks For your help
S
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Old 11-04-2014, 08:48 AM   #2
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They have grown in popularity by me for homes, the external condenser is typically the size of a large brief case (not sure the size of this one). The internal unit looks like baseboard heading mounted high in the room. Now I won't say it won't work (heck I've seen window A/C's in boats), just not sure it would be up to the shock and vibration of an operating boat, in addition come time to sell I don't see it as a selling point.
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Old 11-04-2014, 09:55 AM   #3
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The mini split units can certainly work on a boat. But where are you going to put the external condenser? Also that external unit on a boat will be a throw away item after 5 years. They aren't built for continuous salt air exposure.

There is a reason that marine A/C units are made with stainless steel pans (some at least), cupronickle condensers, etc.

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Old 11-04-2014, 10:20 AM   #4
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Currently helping a friend who is purchasing a N46.. there is a N46 for sale
(Tigerbalm) in Thailand with two mini split systems on board.. the main cabin roof has both outdoor units mounted on it.. no worse looking that a propane locker or life raft.
With the exception of the god awful indoor air handler they are a nice unit..
(although they are available with hidden ducted air handlers for additional $) No clogging of the ac seawater lines with grasses or critters for those in high fouling areas would be really great. Might need to do additional vibration dampening if mounted above the main cabin though.

Mini splits are available all the way up to 22SEER and are the most efficient air source units available
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Old 11-04-2014, 11:24 AM   #5
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1) Being "ductless", it's not going to cool or heat your entire boat very well unless it's just one large cabin.

2) As mentioned above where will you put the external condenser and how long do you expect it to hold up to saltwater?

3) "Pumping sea water" is one of the more efficient heat pump designs. In the summer, the water is usually cooler than the ambient air and in winter it is usually warmer. That translates into efficiency.
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Old 11-04-2014, 01:18 PM   #6
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Ron:

Your points 1 and 2 are very true. But I don't think 3 is. When you count the amperage draw of the raw water pump, marine air conditioning systems aren't so efficient. Typically they require 13-14 amps AC to produce 16,000 btu of cooling which is roughly a SEER of 9-10.

The efficient mini split systems do much better than this using air as the condenser cooling medium. The cheaper ones have a SEER of 12 and the better ones are in the teens. They obviously have large and efficient condensers to allow them to do this.

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Old 11-04-2014, 01:42 PM   #7
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they also make mini-split systems with one condensor serving multiple evaporators , but you still have to contend with the condensate from each unit seperatly,
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Old 11-04-2014, 06:18 PM   #8
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For many ICW cruisers that rarely see green water over their bow...the units wouldn't see much more salt air than a beach house.

I could be wrong...but I'll bet their longevity out of direct salt spray isn't all that bad.
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Old 11-05-2014, 06:14 AM   #9
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Visiting Turkey and cruising in the area as far as Greece and Croatia , there are dozens and dozens of boats with these installed.

On larger (50-80ish) boats they are simply bolted to the stern rails as a life ring would be.

Far too many for there to be problems , and yes it is all salt water.

Depending on compressor size more than one interior units can be run for zone control.

These speed up or slow down the compressor for minimal energy use at less than full blast.
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Old 11-05-2014, 08:15 AM   #10
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Quote:
Originally Posted by djmarchand View Post
Ron:

Your points 1 and 2 are very true. But I don't think 3 is. When you count the amperage draw of the raw water pump, marine air conditioning systems aren't so efficient. Typically they require 13-14 amps AC to produce 16,000 btu of cooling which is roughly a SEER of 9-10.

The efficient mini split systems do much better than this using air as the condenser cooling medium. The cheaper ones have a SEER of 12 and the better ones are in the teens. They obviously have large and efficient condensers to allow them to do this.

David
I think Ron's point is that the water is almost always cooler than the air during warm weather, and warmer than the air during cool weather.

We have these mini-splits at the new house we moved to when we stopped living aboard full time the beginning of last year. They are the latest technology, brand new when we moved in. The house has a lot of glass and almost no insulation in the ceilings due to design... not dissimilar from a boat. The house is about twice as big inside as the boat, and our electricity bills (both based on metered usage) are far more than double what they were on the boat. Both in the same part of North Carolina, same weather. Throw into that block heaters on the two engines (1000w immersion thermostatted) and the genset (250watt pad), on virtually full time during November through March which certainly helped heat the boat a bit but most of the energy going into the blocks.

So I'd say the only compelling reason for the mini-splits is initial cost of ownership, and, any potential longevity issues aside, less maintenance (such as cleaning/flushing the system to eliminate marine growth, and cleaning the strainer regularly). In exchange for which you have these relatively big ugly fairly noisy things mounted outside your boat. I can see it on a houseboat or similar craft, but personally, no way on a most boats like ours or a typical trawler.
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Old 11-05-2014, 08:33 AM   #11
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I think Ron's point is that the water is almost always cooler than the air during warm weather, and warmer than the air during cool weather...............
That is exactly my point and the unit will be more efficient because of the greater temperature difference.

One of the most efficient heat pump designs for residential and commercial systems is the "geothermal" system. This system uses piping buried in the ground or water drawn from wells because the earth temperature is cooler than the air in the cooling system and warmer than the air in the heating season.

Put another way, you can get more heat from warm earth (or water) than from cold air. And discharge heat more effectively into cold or cooler earth or water.
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Old 11-05-2014, 08:37 AM   #12
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The same type of units are very popular over here, only transferring the heat the opposite way. They are primarily used for heating houses. Even with a single (inside) condenser, the installation will a give nice heating to the house, of course unless you close all doors.

Mitsubushi are among the best rated units.

I have seen them installed on a few boats now. Seems to fare pretty well
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Old 11-05-2014, 10:51 AM   #13
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Quote:
Originally Posted by caltexflanc View Post
I think Ron's point is that the water is almost always cooler than the air during warm weather, and warmer than the air during cool weather.

We have these mini-splits at the new house we moved to when we stopped living aboard full time the beginning of last year. They are the latest technology, brand new when we moved in. The house has a lot of glass and almost no insulation in the ceilings due to design... not dissimilar from a boat. The house is about twice as big inside as the boat, and our electricity bills (both based on metered usage) are far more than double what they were on the boat. Both in the same part of North Carolina, same weather. Throw into that block heaters on the two engines (1000w immersion thermostatted) and the genset (250watt pad), on virtually full time during November through March which certainly helped heat the boat a bit but most of the energy going into the blocks.

So I'd say the only compelling reason for the mini-splits is initial cost of ownership, and, any potential longevity issues aside, less maintenance (such as cleaning/flushing the system to eliminate marine growth, and cleaning the strainer regularly). In exchange for which you have these relatively big ugly fairly noisy things mounted outside your boat. I can see it on a houseboat or similar craft, but personally, no way on a most boats like ours or a typical trawler.
Your comparing apples and cucumbers..
You have to figure the CUBIC volume when looking at HVAC.. and I bet the house is five times the size.. at least.
I spend a average of $ 50 a month on electric load to keep a 40' trawler 55 deg. in the winter.
I spend a average of $180 a month on electric keeping a 3000 sq. ft home with 18' ceilings in part of it.. including a 1600 sq. ft barn.. the home is a air source heat pump set at 68. The house has a occupant load of three.. one being a teenage daughter that I swear lives in the shower.

The point is the house has a HUGE load by comparison. Another factor is most conventional marine ac systems that are also used to heat are pretty much worthless at 45d. water temps as the exchangers are not big enough to get enough heat out of the water. Most mini splits will produce down to 32d air temps, some in the low 20's.
They have no fouling issues in heavy nutrient rich waters. Would I want one on my current boat.. no way. not enough room to have the evaporator. But if I had a 50' plus with a upper deck with a lot of room I would consider them.
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Old 11-05-2014, 01:05 PM   #14
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In the Orient, it's also common to see this type of A/C on boats. Here's a refitted Krogen Manatee in Hong Kong that shows the wall unit piped up to the boat deck where the condenser in mounted in a box behind the wheelhouse, a line run of only about 5 ft. or so.
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Old 11-05-2014, 01:42 PM   #15
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Nice way to conceal the condenser, but that wall unit, yuk.
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Old 11-05-2014, 01:49 PM   #16
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Greetings,
Mr. Mm. I disagree. The "wall unit" is a simple, elegant solution mirrored by the corresponding unit on the starboard side which, I suspect, can readily be used for storage. Something which many boats could use more of.
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Old 11-05-2014, 01:52 PM   #17
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Lets agree to disagree, trust me Fleming (add boat manufacture here) won't be putting in this "elegant" solution!
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Greetings,
Mr. Mm. I disagree. The "wall unit" is a simple, elegant solution mirrored by the corresponding unit on the starboard side which, I suspect, can readily be used for storage. Something which many boats could use more of.
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Old 11-05-2014, 02:25 PM   #18
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A guy I used to know had a Walmart window air conditioner mounted in his boat and I've seen the same on other boats, most noticeably what would otherwise have been a classic Chris Craft cabin cruiser.

You pays your money and you takes your choice! Me, I would rather have the standard water cooled hidden marine AC unit even if I have to spend a few more dollars.
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Old 11-05-2014, 02:28 PM   #19
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Your comparing apples and cucumbers. ..............
Are you claiming that I am wrong about the efficiency of heating or cooling water vs. air or are you on another track entirely?
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Old 11-07-2014, 06:21 AM   #20
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>So I'd say the only compelling reason for the mini-splits is initial cost of ownership,<

The cost of a good unit like a Mitsubishe or Panasonic is not low or cheap,

the crap Chinese look alike knock off stuff costs half or less , but works 1/4 as well.

Some are just std compressors hung outside , no saving over a window unit at all.

Converting the line voltage to DC is required for the compressor speed control.

The efficiency of these units comes from the variable speeds , that allow the compressor to match the load.

This is an area where Quality will give the SER you are purchasing.

In boat/RV refrigeration this was tried , but having a unit run constantly (as is the most efficient) to provide just the proper amount of cooling failed.

The customers did not understand the concept , and complained the unit was broken > It ran all the time!
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