| What capacity DC watermaker is right for my boat? |
A couple on a typical cruising boat will need a minimum of 8 gallons or 30 Liters. per day for drinking, laundry, showers and washing dishes if water is used very conservatively. Common conservation methods are: Using foot pumps versus pressurized freshwater (at least in the galley), taking saltwater showers and rinse with freshwater, pre-rinsing dishes with seawater, washing fruits and vegetables with saltwater and substitute fresh water with saltwater for cooking where possible.
Wash downs of deck and equipment after passages and a more relaxed water consumption will require about 13 gallons or 50 Liters. per day per couple.
Boaters often regret that they initially did not install a larger system. A good rule is to fit the largest system you can afford that can be installed without compromising valuable storage space. Larger systems make better use of times when surplus energy is available and run less often, therefore requiring less maintenance and filtration cost.
If the main engine is used for charging and/or powering the fridge/freezer regularly, the installation of a high-output belt driven system should also be considered. |
How much power do I need to run a DC desalination system?
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Depending on the model you will need to provide 20 to 38 amps at 12.5 V DC during one hour of operation. Larger systems are more practical as they can produce your fresh water demand in shorter time.
Since most “watermaking” is done while the engine is running or solar/wind charging is at its peak, energy efficiency is less critical than the freshwater output.
Remember, your high-output alternator’s regulator will allow full charge only when the batteries are low discharged and only for a limited time. After the initial bulk charge, the watermaker will run on the surplus power normally not made use of. |
Is it advantageous to install a DC watermaker if a generator is installed on board?
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No. Having a generator on board allows you to use a high capacity desalination system at a far more favorable price/output ratio.
If you like the advantage of a back-up in case of a generator failure, take a look at the ECHOTec small generator/inverter series. These systems produce large amounts of fresh water, are highly energy efficient and can be powered via an inverter at the same total power consumption as high output DC systems. |
Is an energy-recovery watermaker beneficial for live aboard cruisers?
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The idea to use less power to desalinate a given amount of fresh water is challenging and has led various RO equipment manufacturers to extensive research and innovation.
Other than with commercial desalination systems, the energy recovery devices used for DC yacht watermakers consists of a complex single piston and valve system in which the pressurized reject water energizes the incoming feed water stream.
The actual power savings compared to advanced triplex plunger pump systems range in reality from 0% on older survivor type recovery watermakers to 45% on later models. At a typical water demand of 13 gallons / 50 liters per day this would be a maximum saving of 18 amps at 12 V per day which compares to the power, a single 75W solar panel can generate in only 4 hours at the cost of less than $500! Compare this to the substantial extra cost of the recovery type watermaker.
In many cruisers applications a high output alternator provides the power for the watermaker while charging the batteries and makes the need for recovering such small amounts of energy obsolete.
The main challenges of energy-recovery systems are:
Conventional high-pressure pump systems ensure stable operating pressure. This extends the life of the membrane/s by eliminating the significant pressure pulse present in the small piston type energy recovery machines.
Other than triplex plunger pumps, energy recovery devices are not field serviceable;
in case of a defect the unit needs to be returned to the manufacturer or their factory trained service center.
Conventional systems may require a highly reliable, magnetic drive low pressure booster pump for best performance; whereas energy recovery systems are powered by 100PSI feed pumps that operate at the limits of energy efficiency. This adds another serviceable component to the recovery device that may cause maintenance, expense and anxiety.
Due to the complex recovery device and often unnecessarily incorporated electronic circuits, prices for recovery type watermakers range 60 to 95% higher than advanced conventional systems at the same output.
In conclusion, it is questionable if the considerable extra cost and the decrease of reliability through the additional recovery device on yacht watermakers can compensate for the archived power savings. |
When should I install a booster pump? |
If the desalination systems’ high pressure pump cannot be fitted well below the water level, a booster pump will be required. Although the high-pressure pump assists initial water draw, a booster pump improves the performance of the complete system.
A booster pump saves time and money as it helps to gain maximum pre-filter element life and to prime the system after pre-filter changes. It also avoids cavitation at the high-pressure pump intake that could lead to pitting of the pump head.
The power consumption is negligible as the booster pump adds pressure to the total required working pressure of the system. |
Why should I flush my watermaker after every use?
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The freshwater flush exchanges the sea water in the membrane element/s with freshwater and therefore avoids biological growth that will clog the membrane element/s, leading to reduced output and premature failure. Repeated every 10 days, it avoids the need for chemical preservation usually performed for long-term storage.
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Should my watermaker have an automatic fresh water flush?
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The freshwater flush is a useful feature. It exchanges the sea water in your membrane element/s with freshwater and therefore avoids biological growth that will clog the membrane, leading to reduced output and premature failure of the membrane element/s. Repeated every 10 days, it avoids the need for chemical preservation, usually performed for long-term storage.
The main advantage of the automatic fresh water flush is that it will repeat the flush during your absence, often at a user selectable interval.
However, if you leave your boat unattended you must turn off the main battery switch; primarily to exclude the chance of an electrical fire, the most common cause for lost boats together with galley fires! Now, when you need it the most, the automatic fresh water flush will not work as it relies on DC power. In addition, you would always need to leave your entire freshwater plumbing under pressure – not a good idea when your boat is unattended.
Bilge pumps should be directly connected to the batteries. There are divided opinions whether the pumps should be fused or not.
For your peace of mind, disconnect your batteries and perform the easy chemical preservation procedure if you leave your boat for more than 10 days. The widely available preservative Sodium metabisulfite “pickles” your system for up to 12 months. All ECHOTec systems are supplied with enough preservative for three long term storages.
The remaining feature of the automatic freshwater flush would help to save the work of turning the standard manual fresh water flush valve after every use versus automatic actuation of the flush valve (when you shut off the watermaker) for the price of additional cost and the presence of electronic circuits and electro-magnetic shut-off valves all prone to fail at some point in time. |
What are the pros and cons of automatic product water diverting?
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Every desalination system produces water with high salinity and an odor of sulfur (foul eggs) when started up after more than 15 to 20 hours shut off period. Therefore the first product water must be dumped before diverting the fresh water into the tanks.
The automatic product diverter uses an electronic circuit in connection with a probe installed in the product stream to sense the electrical conductivity (remaining salt content) of the product water and switches an electro magnetic valve from the dump to the tank position when the product turns to fresh water.
Other than the need of incorporating electrical components that can and will fail at some point in time, the probe cannot sense odor and therefore the automatic diverter allows a certain amount of smelly water to enter the tank every time the system starts up.
On watermakers operated only a few hours a day the amount of bad product in relation to the water produced is much larger than on commercial systems operating continuously.
Many users of yacht watermakers with automatic diverters report that they got used to the scent of their water but guests will mention the strange taste.
The best and always safest procedure is to test the first product water for odor and manually divert it to the storage tank when the product is clean. |
What is backwash?
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The backwash is often mistaken for freshwater flush. Backwash refers to the return of the feed water stream in media filters often used on land based desalination systems where silt and other sediments would quickly clog the pre-filters.
It washes the collected contaminants back into the sea by lifting and tumbling the filter media under flow.
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Can I operate my desalination system in brackish or fresh water?
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Yes. Manually operated DC systems like the ECHOTec DML Series allow you to regulate the operating pressure in order to process feed water from freshwater in rivers and lakes to seawater in the Red Sea ranging from 36 to 41 ppt.
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Where can I purchase consumables?
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Other than most brands, ECHOTec watermakers do not require proprietary consumables. Our pre-filter housings and pressure vessels are built to standard sizes in order to allow replacement with widely available spare elements.
All spares and consumables are also available for same day shipping with FedEx from parts@echo-marine.com |
Can I clean the pre-filter elements?
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Yes. Pre-filter elements can be cleaned several times before you have to replace them.
You should use only pleated polyester pre-filter elements at the micron rating specified in the owner’s manual.
String wound or fiber type filter elements cannot be cleaned, have a ten times lower dirt-holding capacity and therefore are not cost efficient.
Household under-the-sink filter elements are made from the wrong material; they will fall apart in seawater which will cause fouling and damage to the membrane elements.
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What is the life expectancy of an ECHOTec watermaker system?
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With proper maintenance, the life expectancy is 20 years and can last the yachts life time.
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How loud are ECHOTec DC watermakers?
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ECHOTec watermakers are the quietest triplex plunger pump desalinators in the world.
They are about 10 dB quieter than other brands on the market.
The system 260-DML-1 creates even less noise. Due to its very low pump RPM it runs with a negligible hum.
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