A marine chiller system, also known as a chilled water air conditioning system or marine water chiller, is the optimal a/c system for boats larger than 50′ (although are used often used on vessels 40′ or larger as well). The marine chiller circulates cold freshwater through pipes throughout the vessel, releasing the cold air via blowers, cooling cabins quietly and efficiently.
Vessels that can accommodate a marine chiller greatly benefit from the green, energy-efficient, high-performing system. In this article I will explain how a marine chiller system works, the benefits of a marine chiller over other marine A/C units, and what size chiller system you should use on your vessel.
How A Marine Chiller System Cools Your Yacht By Circulating Cool Freshwater
A marine chiller system consists of:
- The chiller
- Air handlers installed throughout the vessel
- Freshwater piping (or water hoses) connecting the chiller to the airhandlers
- The seawater system
The chiller consists of typical AC components: the compressor, condenser, and evaporator. The chiller is charged with R-410A, an environmentally safe refrigerant, that circulates throughout these components.
The airhandlers consist of a blower and a coil. Freshwater circulates back and forth between the chiller and the airhandlers through insulated piping or water hoses.
When cooling, warm cabin air is drawn (or blown) across the airhandler coil by the blower. Heat is removed from the room as it passes through the coil, and then cool air is blown back in. The heat drawn from the room is then transferred to the freshwater, and carried by the piping back to the chiller.
The water then circulates through the chiller, where the heat is transferred to the the refrigerant in the evaporator, cooling the water again. The heated refrigerant is compressed in the compressor, and then circulated through the outer tube in the chiller’s condenser coil.
So where does the heat/hot water go? How does the system get rid of it?
This is where the seawater system comes into play…
Seawater circulates through the condenser via the seawater system. The heat transfers from the “heated” refrigerant, to the seawater, and pumped overboard along with all the original hot cabin air!!
A marine chiller system is literally a very cool process!
Advantages / Benefits of a Marine Chilled Water Air Conditioning System Over Other Marine AC Systems
Marine Chiller AC systems are considered some of the most efficient AC systems for boats. This is for several reasons:
- Maximum performance and durability
- Customization of AC system to your vessel’s specific cooling needs
- Highly efficient – lower electricity consumption and a reduced peak electrical load
- Very environmentally friendly
- Each air handler can be turned off without turning off the system
- No limitation of handlers in a system, or distance to each handler
Also, while an individual marine chiller can go up to 180,000 BTUs, several units can be used together in order to provide even more if needed.
What Size Marine AC System Should You Purchase For Your Yacht or Boat?
This rule of thumb should go for not only marine water chiller AC systems, but all AC systems, including split and self-contained AC units.
You need to make sure you do not underestimate the amount of power of your new marine AC system. If you underestimate the amount of BTU’s needed, you will be very hot, uncomfortable, and unhappy with your new unit!
However, overestimating, or “oversizing” your ac system will lead to “short cycling”, where the AC system doesn’t have enough time to properly remove the humidity of the vessel.
The general rule of thumb for choosing the proper marine AC system for your vessel is 14 BTU’s per cubic foot of air conditioned space.
If it is an area that is used often during mid day, and where lots of sunlight comes in, it may be best to use 16 to 10 BTU’s per cubic foot.
For areas below deck, if you only use your vessel in the evening hours, or if your boat is covered / out of the sun before entering, you can usually use 10 – 12 BTUs.
*Note: For more help in sizing your chiller system for your boat, we can help.
Example of A Marine Chiller System / Marine Chillers
*Note: Since the time we wrote this post, Dometic has updated their marine chiller models, which include the MTDX, TWCX, and VARC variable capacity chiller, also available.
We here at Citimarine Store work alongside Citimarine Yachts, and have taken time to research and select top brands and equipment for yachts and larger boats. One of the most popular marine chiller units is the Dometic/Cruisair MTD.
This chiller system is environmentally friendly, provides installation flexibility, maximum performance, and ease of accessibility in order to repair and maintain. The flexible hose improves customization of AC set up, and all the seawater connections are reinforced through stainless steel.
The MTDX is available in capacities ranging from 24,000 to 120,000 BTUs per unit, and multiple units can be used to provide even more cooling (or heating).
Reasons Why Dometic’s Marine Chiller Systems Are Our Top Choice:
- Designed for installation flexibility and customization
- Reverse-cycle heating
- Large drain fitting for quick condensate drainage
- Stainless-steal seawater piping
- Easy to clean and maintain
- Expansion valve ensures top performance over a wide range of conditions and temperatures
- Maximize performance of the “green”, environmentally-friendly refrigerant
I hope this article provided you with an in-depth understanding of marine chiller AC systems, and how to pick the right one for your own vessel.
We also carry the affordable and highly-efficient Webasto Marine Chillers, here.
Have a good one!
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