Split-system air?

[CapnCrunch]

Does anybody have experience with split-system air systems? I will be living on a 44' motorsailer in the caribbean and am thinking that I want to be able to cool the salon and state room independently but dont really want to run air duct or refrigerant lines from a central unit. I will be depending mostly on solar-charged battery banks for power so efficiency is a major concern.

[SV Bacchus]

I freely admit to ignorance on marine air but I am confused by your post. So I am asking my stupid question of the day. I do get one a day, right?

You say split air system but then say you don't want to run ducts or refrigerant lines. Are you saying you want two independent systems or is there a way to have a split system without ducts and/or refrigerant lines?

I am keenly interested in the answers as my prospective vessel has two non-functioning A/C units and I'm will replace both once they are mine.

[CapnCrunch]

"Split system" is a type that uses a central "chiller" to cool water which is then pumped through low pressure hoses to heat exchangers in the areas to be cooled rather than pumping refrigerant to the remote heat exchangers or using flexible ducts to carry chilled air to air vents.

[DeepFrz]

We just had a long thread dealing with 12 volt a/c units. you might want to check that thread out.

[CapnCrunch]

Yeah. I read that thread and it was very informative. But I'm specifically looking for info on split systems which werent mentioned in that thread. Unless I just missed it.

[transmitterdan]

The most efficient split system uses long refrigerant lines. Much smaller and less expense. Really big systems (50k btu) can use chilled water.

I doubt you can run any effective AC for a 40+ foot boat on just batteries and solar. Basically for a split system you need about 11A at 12V per 1,000btu. For a boat that size you probably need 20,000btu to cool it in summer. That's a lot of amps and quit a few kWh to get from just solar and batteries.

[CapnCrunch]

I should probably be more specific about our plans and mention that the boat is a pilothouse sloop motorsailer. We only plan or cooling one area of the boat at any one time and mostly the stateroom at night. During the day, we plan to be mostly on deck or ashore but would probably cool the salon while under engine power. I also plan on adding one or two wind generators.

[sck5]

sounds really complicated compared to just installing two separate systems and getting a generator. Or better yet, if you are in the Eastern Caribbean then rely on the trade winds to cool you at anchor and the AC run on shore power to do it at the dock. That is what most people do. (If they use AC at all)

[CapnCrunch]

It's not complicated at all. You have a central chiller unit that will probably be located in the engine compartment and (in this case) two small air handlers in the areas to be cooled. The only difference is that a split-system pumps chilled water instead of compressed coolant -- much cheaper and less messy to install and maintain. At this point, I'm not determined to use this type of system, I'm just weighing all my options.

As for relying on trade winds; they are not as reliable in a sheltered anchorage as the "mozzies" are and we don't really plan on spending a lot of time in expensive marinas. And I get really tired of the sound, smell and mess of generators - even the small "quiet" ones.

[Sailmonkey]

Split systems have a compressor separate from the evaporator.

Chilled water systems are what you're describing, and really aren't practical in the size you're looking at.


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[Hearts Content]

Originally Posted by DeepFrz

We just had a long thread dealing with 12 volt a/c units. you might want to check that thread out.

Searched on "12 volt a/c units" didn't get anything?

[DeepFrz]

Try again. Use the google custom search.

[transmitterdan]

A chilled water system is much less efficient than simple remote evaporator in sizes less than 50K but. The reason is that chilled water adds another layer to the thermal cycle and it just doesn't have the math behind it for small cooling systems.

Add up the power required for both types and you will see the answer.

[CapnCrunch]

Originally Posted by transmitterdan

A chilled water system is much less efficient than simple remote evaporator in sizes less than 50K but. The reason is that chilled water adds another layer to the thermal cycle and it just doesn't have the math behind it for small cooling systems.

Add up the power required for both types and you will see the answer.

I suspected as much but wanted someone to confirm it for me. Thanx for the responses y'all.

[SV Bacchus]

Originally Posted by CapnCrunch

"Split system" is a type that uses a central "chiller" to cool water which is then pumped through low pressure hoses to heat exchangers in the areas to be cooled rather than pumping refrigerant to the remote heat exchangers or using flexible ducts to carry chilled air to air vents.

Ahhhh, thanks for the clarification. Doesn't sound like it would work for me and the setup I am looking at doing. Besides, I like my cold air cold and not sure chilled water will get it to the temp I am looking for.

On a positive note, I am now a little smarter!