| What capacity AC watermaker is right for my boat? |
The water consumption on a cruising yacht depends on the number of crew, the use of the vessel and the way the water is consumed. It ranges from 13 gallons per day for a cruising couple that uses water conservatively to 300 gallons and more on larger charter boats.
If you know your daily water demand, simply divide the amount needed by the hours your generator runs every day. The result is the GPH rating of the watermaker that suits best your application. E.g.: 50 gallons / 190 liters per day consumption at 1.5 hours generator running time requires a watermaker with a minimum capacity of 33 gallons / 125 liters per hour.
It should be avoided to run the generator only to produce fresh water. On larger yachts, where the generator runs always or most of the day, keep in mind that larger capacity watermakers run less, 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 an AC desalination system?
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High output AC yacht desalination systems consume about 9 amp/h at 230 VAC or 19 amp/h at 115 VAC for a production of up to 60 gallons or 227 liters per hour. This will require a generator of 4.5 KW or larger to start the system.
The highly power efficient ECHOTec small generator/inverter series with capacities of up to 32 GPH can be started by small to medium sized generators or inverters and leave ample power for other equipment when running. |
Is it advantageous to install an 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 the installation of an energy-recovery watermaker beneficial on boats where a generator is fitted?
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The idea to use less power to desalinate a given amount of fresh water is challenging and has led various 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 watermakers range in reality from 0% on older survivor type recovery watermakers to 45% on later models. At 32 gallons / 120 liters per day, the typical water demand on a larger live aboard cruising yacht, the archived power saving would be less than 2 amps at 230 V AC per day and is therefore negligible.
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 a factory trained service center.
Conventional systems may require a highly reliable optional 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 are 60 to 95% higher than for 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 energy recovery device on yacht watermakers can compensate for the minimal total power savings.
If you like the advantage of a DC 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. |
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 the membrane element/s 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 system 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 AC watermakers?
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An important consideration in the choice of the right desalination system is the amount of airborne noise transmitted by the high pressure pump.
Rotary piston pumps run at very high speeds and create a loud pitching noise. Even so more advanced systems have full sound enclosures, they are not suitable for installations close to inhibited cabins.
Plunger or piston pumps are considerable less noisy and create lower frequencies as they run at low RPM. The ECHOTec triplex plunger pumps are the quietest high pressure pumps in the world. They are about 10 dB quieter than other brands on the market.
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