Chiller vs split?

The three Cruiseair AC units on my 2005 Eastbay 47 are original and showing signs of impending failure. This is not unexpected and we used that to haggle during the purchase.

When we make the change I'd like to consider adding supply ducts to the two heads, as they have nothing now. They get kind of stuffy on hot days and cold as the balls on a brass monkey in the winter (especially when the fresh air dorades were left installed!). That and potentially splitting the starboard stateroom out onto it's own zone instead of sharing the master. It only has an air speed control now (and even that has decidedly little adjustment range).

Making the change wouldn't come without labor, of course, as the handlers for the salon are on the flybridge and are fed up through the pillars. I'm sure that'll burn some hours at the yard. If I just stayed with the split system there's a 'chance' I'd be able to continue using the existing refrigerant lines instead of running new. But, then again, they're original and there's no reason to think they won't have problems appear when the replacement process gets underway.

I'm expecting whatever we go with would still require using the generator for power when we're not on shore power. That's fine. But I'd certainly be willing to consider lower power consumption units. Ones that use engine heat wouldn't be as practical as lots of our boating involves time out on the hook. It's enough to have the generator running, not the C-12s.

A friend with a sedan bridge Sea Ray switched to a Dometic chiller system and raves about it. I'm just starting the investigative process and am looking to find pro/con conversations about it.

Anyone had experience changing from a split system to one using a chiller? And have an installer in the central Maryland (annapolis, kent island, etc) area to consider? Or, perhaps more importantly, to avoid?

Here are some thoughts:


If you are totally going to revamp your heat pump system, then I would look at a chiller system. You can't reuse the evaporators from the split system as they are sized for freon, not cold water. It all depends on how easy it is to run the water piping.


A central chiller system will probably be more robust than multiple split or stand alone systems, but you are putting all your eggs in one basket.


So consider a combination of split and self contained systems. Maybe a self contained system for the main salon and a split system for the two state rooms.


David

Agreed, re total revamp and effort to run lines.

We don't live on this so I'm not terribly worried about single point of failure, but it IS a point worth bearing in mind.

I've not read too much about 'self contained' systems. The air handlers/exchangers for the salon are located up in the flybridge forward compartment (a non air conditioned space, essentially like a household attic). Making them 'stand alone' would certainly simplify the plumbing. If such a thing could run in that kind of location, that is.

Going to chiller would be quite the endeavor. Very different type of system, very different type of controls. No way would I try to retrofit a boat with a chiller when it started life with multiple stand alone freon units.

One big detail that Dave pointed out is with a chiller you have one system, that is it. Any failure and you will then have no ac. With multiple units, one can go down and you can still have some ac.

Also, the chiller unit sized for the whole boat is going to be a big machine with lots of start up and running amps. When it starts it could stomp your gennie.

Bill,

My GB came fitted with Marineair (now Dometic) chilled water a/c system.

To my mind it is one of the best systems on the boat. Even in the middle of summer in (tropical) Brisbane it cools the interior completely, so much so that we never have it turned to full capacity. Other GBs of similar age with split gas systems dont seem to enjoy anywhere near the same cooling capacity. It will be a big job to convert your boat to chilled water system, but once you have done it you will never look back.

As for a/c in the heads, like yours my GB didnt have that either. We solved it pretty easily by coring a small hole in the main head and some extra ducting to 'steal' some of the airflow from the vent for the nearby cabin. Because the chilled water system has so much surplus cooling capacity, 'stealing' that little bit of airflow and redirecting it to the head hasnt made any noticeable negative impact in the cabin. The cost of this exercise for me was a couple of hundred dollars only.

Hamish.

Looked at chill water systems when refitting my boat. Ultimately decided not to and will offer a few observations:

For my application, there would be 2 chillers as part of the time one would be sufficient (3 would have been luxurious). There was also a coil off the coolant loop on the engine for heat under way. Finally, a fourth zone would be added so each stateroom would have its own unit.

Positives were quieter units and being able to utilize heat from the engine while underway.

Negatives:
The system isn't anywhere near as efficient. This isn't a big deal if you're sizing everything on a new build. However, depending on your current generator capacity, it may be significant (it was on mine).

Depending on number of zones, chillers, and heat exchangers, the plumbing can be substantial. Hoses (with insulation) can get tough to route.

The other thing to consider is that the zone outputs can vary modestly to significantly depending on number of zones calling for cooling and the capacities of the chillers. These units seem to really excel with lots of surplus capacity.

The final choice came down to maybe being undersized on the hottest days or up sizing the generator. Cost was significantly more for the chilled water system.

Ted

The chillers I have seen were on passenger small boat cruisers
65 ft with 8 cabins., plus main salon, crew quarters , galley etc.

The advantage was 3 compressors simply cooled or heated water , so if only one was required power draw was minimal.

Should a compressor fail it could be removed easily and sent off to fix , no Freon priced tech to come visit.A spare unit was in inventory.

Any problem in the distribution circuit meant repairing a pipe or hose , and refilling with anti freeze , no Freon tech .

Zone control was a snap for every cabin and the other tempered areas.

A modern true mini split system would be more efficient than a chiller or multiple ancient ducted units , as the compressor speed can be varied.

Weather the mini split could be installed and not look bad would be the challenge.


Here is a boat with chillers.


https://pilotonline.com/news/article_a98b736a-c279-52e1-9724-6f4775daaeda.html

We have split systems on our current boat, and are building a boat with chillers currently. The 60-70' range seems to be where chillers start to appear, I think because you otherwise end up with 5, 6, 7 or more split systems.


Lots of good advice so far, so only a few things to add.


- A tempered water system can of course heat as well as cool the boat, just like a split system. But integrating in engine heat or diesel heat can be tricky. It's not really rocket science, but you end up with two different manufacturers who want to draw clear boundaries around their system, and want nothing to do with the other system. So you end up with nobody who wants to own the integration of the two systems. I'm helping a friend work through this now, and we are ending up owning the design and support of the integration of the two systems.


- Stand alone systems can be convenient, but keep in mind that each needs a supply of raw water which means a sea cock, strainer, pump, hoses, and overboard discharge. And pumping raw water up to your flybridge will require some special attention to be sure the pump has enough lift.


- Chilled water piping must be insulated or you will end up with condensation dripping throughout the boat. I think this would be one of the hardest parts in a retrofit. In our new build, the supply and return lines are probably 2.5 to 3" in diameter each. I wouldn't want to be the guy fishing that through an existing boat.


Personally, I would stick with a split system.


BTW, in what way it it an ailing system that requires full replacement? That's what surprises me the most.

twistedtree said:

We have split systems on our current boat, and are building a boat with chillers currently. The 60-70' range seems to be where chillers start to appear, I think because you otherwise end up with 5, 6, 7 or more split systems.


Lots of good advice so far, so only a few things to add.


- A tempered water system can of course heat as well as cool the boat, just like a split system. But integrating in engine heat or diesel heat can be tricky. It's not really rocket science, but you end up with two different manufacturers who want to draw clear boundaries around their system, and want nothing to do with the other system. So you end up with nobody who wants to own the integration of the two systems. I'm helping a friend work through this now, and we are ending up owning the design and support of the integration of the two systems.


- Stand alone systems can be convenient, but keep in mind that each needs a supply of raw water which means a sea cock, strainer, pump, hoses, and overboard discharge. And pumping raw water up to your flybridge will require some special attention to be sure the pump has enough lift.


- Chilled water piping must be insulated or you will end up with condensation dripping throughout the boat. I think this would be one of the hardest parts in a retrofit. In our new build, the supply and return lines are probably 2.5 to 3" in diameter each. I wouldn't want to be the guy fishing that through an existing boat.


Personally, I would stick with a split system.


BTW, in what way it it an ailing system that requires full replacement? That's what surprises me the most.

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There are three compressors in the engine room. One of them is making a significantly greater racket than the others. It's one of the two salon units (port & starboard) so I'd still have AC if/when it craps out. Definitely a nod toward the redundancy point of view.

Ah, yes, raw water up to the flybridge would likely be a bad plan. Lift, etc. Not to mention not wanting any more raw water piping than absolutely necessary.

My current units all share the same intake and outflow, with about 6' of hose in and 3' going back overboard. Seems wise to stick with short hoses that are in plain sight.

If we stick with the existing 3 zones I'm definitely leaning toward stealing a duct off the stateroom zone for the heads.

The 2 ton mini split I put in is great. I wound up putting the evaporator in the flybridge because it's so big.
Super low power usage. Less than 400 watts after the temp stabilizes to 74.
I intend to cool the salon and forward section with it, and put in a small mini for the aft berth as it will be even less power and should easily run on the inverter overnight.
I may not convert the small on to water cooled and may revert the 2 ton's to normal air cooling as well. Water cooled looks neat and hidden in the engine room, but there are technical issues in doing it you have to overcome.

barnacle, you certainly don't see many air-cooled minisplits (which are residential/land-usage) installed in American boats, but here in Asia and SE Asia they probably outnumber water cooled units, especially on commercial boats.

There was another thread here and some members displayed the shrouds and other ways they built to hide the condenser.

Here where I live we are surrounded by tens of thousands of those things, but I have yet to find one where the noise levels of the condensers were not annoying.

I was wondering what you think about the noise and overall satisfaction.

When we built a new house we went with underground wells for geothermal driving four inside zones. Fantastic results and NO OUTSIDE FAN NOISE. So I'd be very unlikely to switch to an air system.

The pioneer minisplit+ (not the ++), was virtually silent. I hung the evap in the salon for a month or so to make sure I really wanted to modify it. You could barely hear the air move inside if you stood next to the evap. Probably due to their using a long squirrel cage fan.
The condenser fan had some air noise, but it was pretty quiet too. I had it up on the flybridge deck, and had no issues grilling right next to it (sound wise). Hot air blowing up your shorts while grilling was a different matter altogether. LOL

You have to be careful which unit you use if you plan to convert to water cooled. The ++ versions use a high voltage DC variable frequency switching scheme to vary the speed just as the compressor. While even more efficient you can't unplug and discard the fan motor, as they monitor its rpm and the motor controller is integrated in the motor itself.
The + model (17 seer), uses a 2 speed ac fan motor and it's not monitored. So its modifiable, in that you can unplug the fan and the unit will still run. I'm still debating on using the fan voltage to power the water pump, but I need to get a data logger so I can see how the voltage varies over time .
The other big issue is no one seems to be able to suggest proper super heat or line pressures, it's always just weigh the refrigerant in...
Except water cooled condensers are a lot smaller and won't hold nearly as much refrigerant. So just blindly adding in by weight will cause it to be way over charged and the risk of the compressor seeing liquid is right up there.
The easiest way is to not modify it, by far.

Forgot to add, the boat now feels like a house in regard to comfort. No hot and cold spots and it's so quiet I can't hear it at all. It's just awesome compared to the normal boat a/c's

A few things also that I like about those air cooled Mini splits:

- they are super efficient with up to SEER 25+. Perhaps could be run for an hour or two off the inverter
- you can purchase a ducted unit, just like a small version of central aircon, and not have a visible evaporator inside your cabin
- I’ve seen them mounted horizontally on top of the deckhouse, so they could be relatively low key, perhaps hidden with a high “brow”
- very cheap and easy to replace and repair especially in remote countries
- they are not water cooled!

Glad to hear that you’re happy with yours, Barnacle

An additional benefit of the ducted units is the availability of a wall mounted control panel. The wall mount ones dont have wall control panels yet so you need line of sight as the remote is infared. You can wifi control them as well but I use my phone as a hot spot and I have yet to figure out how to connect the the indoor unit via wifi and still have internet.


I am assuming the 9000/12000 btu units will run at 300 watts or less and thats ~24 amps out of the batteries. 2 - 8D's should run it all night.

Where is the condensate generally discharged from the evaporator?

On my 2 ton there are 2 hose nipples molded into the evaps housing, one on each end of it. A 5/8" hose can be used.



The condensation is cold enough to make the drain line sweat like a banshee if it isnt insulated.

what_barnacles said:

I am assuming the 9000/12000 btu units will run at 300 watts or less and thats ~24 amps out of the batteries. 2 - 8D's should run it all night.

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Good point. Reminds me that that a typical digital inverter model can vary (for example) from 7000 to 24000 btu, so you really could run it off batteries, or even a few hours per day off solar, to keep the mold away.

Bill, our Eastbay 43 has 3 of the dometic units. Had them maintained @ Herrington about 2 years ago and they have worked fine ever since. One thing we've noted, some of the "50 amp shore power supplies" will trip out as you reach 50 amp usage - say 3 units + a few other things running. So, staying with 2 of the 3 running has worked great for us.

Ardell

Ardell said:

One thing we've noted, some of the "50 amp shore power supplies" will trip out as you reach 50 amp usage - say 3 units + a few other things running. So, staying with 2 of the 3 running has worked great for us.

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Huh. Thus far our 3 units have not exceeded the draw on any of the 50A connections we've used. I don't know how the engine room & AC units are setup on the 43, but it might be worth checking the actual draw when you're on shore power. A inexpensive clamp-around ammeter would make it easy enough, just measure one of the hot legs to see what's actually being drawn. I'll have to remember to take my clamp one down to the boat. I think I can just get to the separate conductors where they come into the cablemaster storage tub. If I manage to do it I'll report back what I find.

If all 3 are wired on the same leg, you'll overload it in short order