How about an air cooled AC installed on my 42 foot yacht?

[PNM]

I am considering installing a self contained "air cooled" 110 vac AC under my upper helm console and directing the cool/hot air through the ceiling of my salon - directly under the upper helm console. I would get outside air through a louvered opening in the side of the upper helm.

Anybody ever done such a strange thing? Thoughts are appreciated.

 

[Blissboat]

You're planning to use a 110v reverse-cycle wall unit, I take it? I've seen what you're describing in a residential building, with the wall unit placed in an attic, vented to the outdoors and the cool-air discharge ducted through a grid into the occupied space. The condensate drained into a plumbing vent stack. It worked okay, and I imagine it would work the same aboard. Naturally, the unit must be well secured against shifting with the motion of the boat, and you'll have to arrange something for the condensate to drain overboard or into the bilge, etc. Another approach might be a compact mini-split, either 110v or the 12v kind that are widely used on large truck cabs.

 

[PierreR]

An RV type air conditioner should work fine as long as you have enough air flow to it. There is a glassed in large RF antenna glassed in on mine in that area. Cutting a hole would basically destroy that antenna.

 

[PhilPB]

Not sure if you are referencing a portable or window unit. But if you are pulling in outside air, cooling it and then putting that into cabin without an air exchange from inside the cabin you need to rethink the plan.

 

[Keysdisease]

I'm in South Florida.
There are "rooftop" marine units available. My "olde" MS34 pictured had a unit installed under the flybridge console as you describe.

The only downsides are it's "local," cold air had to travel to the forward cabin and the door needed to be open. If you run it underway the flybridge is loud and in our install the hot air blows on the helmsman's feet. The condensate water has to go somewhere. Ours would "travel" stbd side of the bench and drain off the top onto the side weather deck. If you can, I suggest you direct it to somewhere specific, it is irritating.

They are sensitive to circulated air. A couple times we had the upper helm cover on and turned the unit on, and after 10 minutes it turned itself off. Don't do that

The biggest downside was the noise, they are louder than water cooled units, even the self contained units. They are not in a cabinet or under the dinette, they are on the ceiling in the middle of your main cabin/salon.

They do cool well if sized appropriately. Our unit would keep the boat cool all day if turned on early, it did struggle to cool down a "hot" boat if you turned it on at 3pm on a hot July day, or after a run with a hot engine space under your feet.

You can just see the unit peeking out in front of the helm chair

Good Luck

Rooftop Units

www.suremarineservice.com

 

[PNM]

Thanks. Great comments.

Sorry for the length of my comments, but your thoughts waked up my brain .

I might be better off with water cooled marine units. Though I would like to take out all of the wiring bundles and copper tubing - if not already leaking, the tubing will be a problem sooner or later.

The newer self-contained marine units are small and surprisingly quiet, but they require water for cooling the compressor/condenser and drains for the evaporators.

Since my remanufactured Cruisaire unit is only 10 years (and maybe 500 hours old) I hope it can be converted to a more modern freon by replacing the ancient evaporator. If so, I might buy a new compatible evaporator and install it under the settee in my salon, eliminating most of the tubing and cabling and reducing future maintenance cost.

For the forward cabin, I think I can replace the dead compressor in the engine room, that previously cooled the fore/aft cabins, with a small stand-alone unit and install an insulated vent hose through the bottom of a closet directly to the forward cabin.

That leaves me with the master/aft cabin challenge.

I have a currently plugged, screened through hull that no longer provides raw water to the aft head.

1) I could install a new raw water AC pump to this through hull to cool a stand-alone unit in the aft cabin and drain the evaporator into the bilge. Or,
2) I could cut an opening in the aft end of the master cabin (it is currently a solid fiber glass wall that represents the back wall of the doghouse (2' tall x 10' wide). If I were to install one of the new compact "window like units" it would stick out into the 3.5' wide aft walking area about 8 inches. I think I need about 10,000 btu for the master cabin, so I need to learn what is available should I consider this option.

This approach cleans up many future maintenance headaches, frees up storage space previously used by the evaporators, and might only cost about 1/2 as much as recreating the original scheme.

Comments are appreciated.

 

[Turtle Blues]

The footprint of new complete SC units is the same as older evaporator sections. Add soft starts, enclosed fan motors drawing across the exchange coil before the evaporator coil and the quieter compressors my vote is always for replacing and enjoying the upgrade. I did this with the main cabin unit (1of 3) which resides under the flybridge on mine. Did require a step up in the cooling water pump to give it sufficient water but now it is out of sight, quiet, and as opposed to an air cooled unit, not adding heat to the upper station. Plus freeing up a couple of square feet of bilge space.
My 2 cents is parts still cost money and if your time is valuable it's better spent on straight replacement rather that rebuilding a 10 year old unit.

 

[Blissboat]

To me, eliminating through-hulls, strainers, pumps, impellers and hose clamps is worth some creative thought and effort. That's why air-to-air HVAC aboard salt water boats is interesting. Not saying it's an easy alternative (at least not yet, that I know of), but I'm hoping to learn more from this thread.

 

[alormaria]

Buy the real thing. You'll love it.

 

[PhilPB]

When I decided that my 12k btu Aqua Temp ac was not good enough for the boat cabin in Florida's heat I also considered many options. I was very close to getting a 16k btu portable unit that had 2 hoses until I realized that was just an ill-advised kludge. I ended up installing a reverse cycle 16k btu Wabasto FCF Platinum and I'm glad I did. I had an unused 3/4" thru-hull that was the raw water intake for the head after I installed a freshwater flush ME, so I used that for the raw water supply for the new ac. I put the ac unit inside the chart table, installed new ductwork and it works amazing. I can cool down my cabin from 92° to 70° in about an hour. I installed new ductwork on the old ac and that now only for the v-berth and galley but don't really need that unit much except on days where the temp outside is mid 90's. You need to just go for it and buy the proper equipment that is made for your application.

 

[rgano]

Here is a photo of the Dometic Penguin 13.5 KBtu, cooling-only, air-to-air unit installed by a previous owner. It is not 'marine" rated, and you might see a bit of rust on the metal grill work which I have to attend to annually. Otherwise, under the hood, there is no significant corrosion. With all the canvas lowered underway, I was recently able to cool the helm area from 95F to around 85F, and the air was less humid than outside, making it ok for comfort. The downside is the noise overhead. With the noise from the 315 HP Yanmar underfoot at 3000 RPM, the noise from the AC is drowned out, but at low speeds or anchored it is NOISY. I seldom use it, and I would never have installed it on my own hook - opening all side and windows and windshield center section would work ok. I did install a Micro-Air soft start module in it, considerably easing the startup surge.

The downeast cabin came with a Dometic 7 KBtu marine, reversible AC unit which was inadequate. Thankfully, it died of corrosion caused by condensate from a clogged pan drain soon after I bought the boat. I replaced it with a quite adequate Dometic turbo 10 KBtu, also with a Micro-Air soft starter added.

 

[Blissboat]

Here is a photo of the Dometic Penguin 13.5 KBtu, cooling-only, air-to-air unit installed by a previous owner. It is not 'marine" rated, and you might see a bit of rust on the metal grill work which I have to attend to annually. Otherwise, under the hood, there is no significant corrosion. With all the canvas lowered underway, I was recently able to cool the helm area from 95F to around 85F, and the air was less humid than outside, making it ok for comfort. The downside is the noise overhead. With the noise from the 315 HP Yanmar underfoot at 3000 RPM, the noise from the AC is drowned out, but at low speeds or anchored it is NOISY. I seldom use it, and I would never have installed it on my own hook - opening all side and windows and windshield center section would work ok. I did install a Micro-Air soft start module in it, considerably easing the startup surge.

The downeast cabin came with a Dometic 7 KBtu marine, reversible AC unit which was inadequate. Thankfully, it died of corrosion caused by condensate from a clogged pan drain soon after I bought the boat. I replaced it with a quite adequate Dometic turbo 10 KBtu, also with a Micro-Air soft starter added.

The air-to-air rooftop Dometic Penguin looks fine, but that boathouse roof looks magnificent!

 

[rgano]

Smartest thing I have done in a long time was getting a lift-kept boat, with no exterior wood, and a roof over it.

 

[PNM]

A marine AC tech told me the new stand-alone units will fit where most old evaporators are located. I "think" I can use the high & low-pressure copper freon lines that run to/from each evaporator as water supply/return lines from the pump and to the discharge fitting that exits through the side of the boat. The necessary power for the stand-alone units is in-place to supply the old evaporators. The cool air output and return air pathways are already in-place for the old evaporator units.

This approach sounds like a smart solution - unless there is a leak in a copper line - then I will have to fix that.

The tech told me they won't even charge an AC over 10 years old. The labor for finding the leak, fixing the leak, then charging the unit with "POUNDS" of expensive freon (twice for finding the lead, then fixing and recharging the leak), negates much of the cost of a stand-alone unit, and I still have a 10 year old AC that could leak again tomorrow.

Comments are appreciated.

 

[Turtle Blues]

The copper is not sized large enough for the cooling water. Pull the copper and then pull properly sized water hose.

 

[MYTraveler]

I have seen enclosed-cabin Sheriff boats in southern California (where it can be hot enough to make good AC a necessity) equipped with an air-cooled unit on the cabin roof, ducted to blow straight inside. It looked cool to me.

 

[rgano]

Mine is noisy as HELL.

 

[SIBERNUT]

Has anyone considered/used a new mini split on a boat ?

 

[PhilPB]

Has anyone considered/used a new mini split on a boat ?

When I was shopping for my boat I did look at a 40 MT where they installed a mini split but couldn't get it to work. The boat was being sold by widow and didn't know much about the boat as it was her husband's hobby. There were a lot of other questionable things on the boat so I passed.

 

[Blissboat]

Has anyone considered/used a new mini split on a boat ?

I keep asking this same question. So far I have only ever seen a mini-split installed on a high-end custom houseboat. Subject to finding an onboard location for the two major components, mini-splits seem to offer an efficient marine HVAC solution with zero hull penetrations below the water line.

 

[dvarholy]

HVAC technician with 25 years here. The mini splits are quiet and very efficient. In most areas, you will not even need electric heat over the winter. I have attended manufacturer's training that showed these units installed on larger vessels. There are some important things to consider:

Most mini splits, except the smallest sizes, are 208/230 volt. This means you will need two dock cables on separate phases or a generator that produces such voltage.

Most mini splits are not made for the marine environment. This will affect warranty claims, longevity, or even convincing a dealer to install it.

The condensate trays of wall mounted mini splits may spill if you hit a wake or bad weather.

The high voltage communication cable supplied with some units is not marine rated. An appropriate ABYC alternative should be available. RF shielding is also advised.

It is possible the frequency invertors used may affect other electronics onboard.

The outside units often have a high profile that may partly block the radar antenna on certain installations.

Daniel Varholy

'89 Tradewinds 43' MY

 

[Blissboat]

Most mini splits, except the smallest sizes, are 208/230 volt. This means you will need two dock cables on separate phases or a generator that produces such voltage.

Daniel Varholy

'89 Tradewinds 43' MY

It's the smallest sizes that would seem relevant for recreational yachts in the 30' - 50' range, yes? How small is "small," to your knowledge? For example, I have seen compact units mounted on over-the-road truck tractors that are apparently adequate to heat and cool sleeper cabs. Those units must certainly be running on 12v. Those are the installations that make me wonder about using similar equipment aboard a boat.

 

[dvarholy]

Residential 120 volt mini splits are usually 1ton (12,000 btu) or less. These small units are often cool only and not heat pumps. The advantages in such a unit are low cost, high efficiency, often 20 SEER or better, and being readily available. Anything that is capable of 12 volt DC service, such as large trucks, will be much more expensive. With a DC only unit, a larger invertor and batteries would also be needed. I think 12 volt units made for trucks are a great idea if one is away from the dock most of the time.

Daniel Varholy

'89 Tradewinds 43' MY

 

[SIBERNUT]

A lot of trucks now have APUs, small 110v generators

 

[dvarholy]

APU's and diesel heaters are likely due to laws against trucks idling overnight. I have seen these small AC units mounted behind the cabs of trucks at my work.

 

[mvweebles]

Here's a 12v/24v/48v unit for RVs. Compressor is designed to mount under the chassis, though could be mounted anywhere.

https://a.co/d/5GMFB0b

If I were building a new boat, I'd include two design attributes. #1 would be some sort of mini split for cooling - might be 120vac of perhaps the 12vdc (or 24v) but would definitely design in mini splits. Biggest concern would be repairability in distance lands, but an acceptable tradeoff. #2 would be an off-grid style LFP rack mounted battery bank instead of the current Victron iteration of old-school automotive battery architecturepeyrt

 

[Ithaka7]

I think the best solution is still a compressor in the engine room and evaporators in the cabins. The evaporators are relatively quiet. These systems, however, cost a lot of money, I was quoted $15k for replacing 2x 16,000 btu compressors with four evaporators.

If you install stand-alone units in place of the compressors, it is way less expensive ($1.5k per unit) but it is also noisier. You do, however, get modern features such as remote control, etc. but still no inverter.

The air-to-air split units, especially the inverter ones, are much more efficient, very cheap (they cost around $500/12,000 btu here in Europe) and also have the added benefit that in the winter the air-to-air units maintain their heat efficiency down to 20-25F air, while the the marine units lose efficiency quickly when the water temperaturs drop below 45F. For the split systems you need to find the space and the airflow and they do not look good on a boat.

All the other alternatives (portable, window or roof-top air conditioners) do not make sense. They are either as expensive as the marine units or just do not work. It would be interesting to see if a passenger car air conditioning can be modfied to work on a boat.