The Difference Between a Marine Self Contained and a Chiller
Know the difference between the most used air conditioning systems for marine applications.
To talk about this subject first we have to start with the difference of a self contained with a remote condensing unit (RX) before we can actually talk about the difference between regular self contained unit with direct expansion and chiller systems.
The reason remote condensing was made is because 30 or 40 years ago, only piston compressors where available and piston compressors were very noisy. To keep the noise away from the cabin, these systems were installed in the engine room. With the advance of technology and rotary compressors noise was eliminated completely.
Remote condensers became not a necessity They are complicated to install and require licenses, For Freon manipulation Is require that a certified air condition Technician handle them. Self-contained units on the other hand are easier to maintain and installed and it does not require a professional to, they are smaller in size and do not take any extra space from the engine room.
What is the difference between remove condenser and direct expansion with a chiller?
They both need a compressor to run, one is running Freon throughout the boat and uses evaporators on each cabin that are cooling the cabin, the compressor is located in the engine room but there is Freon between the engine room and the cabins.
Chiller systems do not carry Freon instead they work with water, you heat the water or cool the water using radiators in the cabins to do this work.
What is a chiller system?
A chiller System is a cooling system that instead of pumping freon throughout the boat Is cooling water in the engine room or in any location on the boat and that cold water is circulated throughout the boat to be able to feed radiators, and those radiators are taking the Heat from the cabin and putting it in the water the water gets cold again by the chiller and that is one of the big advantage of this it acts as if the BTUs were in a suitcase when the cabin is satisfied and cold the valve closes for those BTUs to be safe and use somewhere else more efficiently like in the Saloon,Those BTUs are in the water and can be allocated to be used when is needed they do not get eliminated by the shutdown.
So in conclusion direct expansion is a compressor that works with gas and the gas cools the evaporator, and on a self-contained unit, this is all in one package. In a remote it is in two packages, two different locations on a chiller system is one unit that is doing everything it's cool in the water and then the air handlers which are radiators are taking the cool or the heat out of the water and putting it in the cabin or any place on the boat.
advantages of a chiller system is that a chiller system that is located in the engine room does not communicate with any of the cabins, is a unit that is operated by turning on and off and is adjusting fan speed based on the temperature of the water and there is no wiring related on the cabins , that particular unit is a very simple system ones you bring power to the unit the unit will know what to do based on the temperature of the water that is circulating throughout the boat the thermostat in each cabin is opening and closing accelerating and decelerating the blower to keep a constant temperature.
What makes some Chiller better than others?
On a Chiller system you are using the ocean water to circulate in the condenser to remove the Heat From the unit and you have another heat exchange that is cooling or heating the water.
When you're dealing with ocean water, metals have the tendency to become affected by electrolysis or to be corroded on the inside based on the quality of the condenser.
Copper nickel is the best option but there are many kinds of copper nickels, there are 70/30 one of the best on the industry also there is 90/10 Is what most of Manufacturers are using right now it is much more economical but they don't last as long, and there are also made out of titanium titanium is great but there is a lot of controversy based on the similarity of the metal that are affected by electrolysis Some experts are saying that is good and some are saying that is no that good But only the years will tell.
On the other side there are on and off chillers and that are variable speed chillers with inverted technology.
On and off chillers will cycle on and off based on the temperature of the water and will have a differential, let's say a unit is set up to run from 7 to 80 degrees so when the temperature of the water fluctuates the compressor will go on and off based on the level of degrees, Because it's coming on and off all the time it brings a lot of wear and tear on these unit.
What I recommend is the inverter technology Which gives the compressor running all the time and you will speed up or slow down depending on what he needs that's why the compressor will last forever and they consume about half of the power require, they require a match motor generator to run and make absolutely no noise, I like this technology much better because it is very reliable
What makes a good air handler for a chiller system?
A good air handler will require a very powerful high-velocity, High static pressure blower. To achieve this ball bearing blowers came out to be very useful to keep the static pressure efficient, adding valves to bypass the flow of the radiator or the air handler comes out to be very much practical because of the pressure on the circulation Loop stays the same all the time, valves opens water goes through radiator, valve closes water bypass and will not go through the radiator.
A good air handler will also have electric heat, there is no reason to run a water circulation Loop In certain situations where heat is not that important but it's always good to have it available heat on one side and electric heat on the other.
Our Units all have electric heat as a standard.
Another thing that makes a great air handler is control, controlling the fan blower speed automatically based on the set point,also memory on the control is a must You definitely don't want to cut the power and have to come back and re adjust every single control.
An easy installation with data cables is a plus and having safety protections for low voltage is also very important Last but not least having a non corrosion stainless-steel drain pan is always great.
International marine HVAC president, DIRECTOR FRIGOMAR USA - MPS Air conditioning refrigeration manufacturer. Quick mabru Power Systems Eckerd College