Watermaker - 12vdc, 220vac, or Engine-Driven

[daddle]

Originally Posted by Pete7

Says salt water rejection is 98.4%, isn't that enough?

It is enough. But not great. Probably saves Katadyn some power consumption.

Sweet fresh water will be around 100ppm, or 99.5% salt removed. The Katadyn's 98.4% removed sounds good (it's specsmanship) but is at the limit between fresh and brackish according to some water standards. But other sources say 1000ppm (97% removed) is acceptable for freshwater. Some marine watermakers produce far better water on far less power.

[Tellie]

A true 500 ppm you'll never taste salt. Usually you'll have to start reaching the 800+ ppm to even begin to notice salt. As a side note (an I have no real proof) but women are more sensitive to the tast of salt then men. Have you wife taste it. If she's OK with it you're good to go.
The 98.4% is what the membrane under ideal conditions is rated at. If you're getting 500ppm it's not operating at it's rated rejection. This doesn't mean the membrane is bad but many other things will influence the ppm readings, bad seals, bad O-rings, low pressures etc. Two identical water makers in the same conditions will usually give different ppm readings. One of the reasons comparing your buddies units to yours is a waste of time.

[Jon Hacking]

Originally Posted by daddle

Katadyn datasheet claims 29 l/h max (8 g/h) at 18A@12V (12A@24V) producing 500ppm (avg) water. That's at the limit of what can be called freshwater. Does it taste a bit salty?

You're absolutely right that 500ppm is on the hairy edge of what we should be drinking long term. Anything more & you risk kidney stones & other unpleasantness.

But people are unlikely to notice it initially. When our membrane went south (in the middle of the Indian Ocean, after 5 years) it was friends who usually like our sweet water who noticed it. We hadn't noticed any problem at all. When I tested it, it was only producing 1300ppm water. That's more than 2.5x what we should be drinking & you could only just tell it was a bit salty. So don't trust taste! Get a meter. They're only ~$30 or so.

We've also found that running both pumps produces better quality water. The membranes seem to like the higher pressure. Unfortunately, this also puts more strain (wear) on our pump heads, a chronic problem with older Spectra (actually, ShurFlow) pumps. It's also slightly less efficient, as we don't get quite 2x as much water but it costs us 2x as much current.

[Tellie]

Originally Posted by Jon Hacking

You're absolutely right that 500ppm is on the hairy edge of what we should be drinking long term. Anything more & you risk kidney stones & other unpleasantness.

But people are unlikely to notice it initially. When our membrane went south (in the middle of the Indian Ocean, after 5 years) it was friends who usually like our sweet water who noticed it. We hadn't noticed any problem at all. When I tested it, it was only producing 1300ppm water. That's more than 2.5x what we should be drinking & you could only just tell it was a bit salty. So don't trust taste! Get a meter. They're only ~$30 or so.

We've also found that running both pumps produces better quality water. The membranes seem to like the higher pressure. Unfortunately, this also puts more strain (wear) on our pump heads, a chronic problem with older Spectra (actually, ShurFlow) pumps. It's also slightly less efficient, as we don't get quite 2x as much water but it costs us 2x as much current.

Hi Jon,

I assume with two pumps you either have the older 380C, Gulfstream or Santa Cruz model. A few comments on your post. First, you are absolutely correct. A membrane that is slowly going bad and gradually increasing the PPM the owner will not notice the difference as they acclimate to the saltier taste. A reading of 1300 PPM and other people would notice the salt taste right away. A calibrated TDS meter is a good method to make sure.
To the performance of your water maker. Running both pumps will make better water because as you state the pressures are better as is the flow. But if the rest of your Spectra system is operating at specs you should be getting about 14-16gph. This can only be accurately measured by a physical measured and timed measurement. The flow meter can be off, especially if you are seeing rust colored stains in the flow meter. There might be a chance there is a pressure issue in the Clark pump. The feed pump heads should not be wearing out any faster because you run them both at the same time. Voltage is very important. I'm guessing your unit is about 8 years old give or take. It would not be unusual for feed wires, connections etc. to have some higher resistance affecting the feed pumps. You Spectra is voltage sensitive. You may have already done this, but check the voltages at the connection terminals while the system is running for both pumps and of course check the source for voltage as well as see what kind of voltage drop you have. Removing, cleaning and even replacing wire terminals often makes a big difference in a system this old. Even on the best maintained units. Also as you stated the feed pump heads are Shurflo. But they are made by Shurflo and specifically designed for Spectra. A quick cross reference with Shurflo will confirm this. Many people have tried to use other Shurflo models that bolt right up but they won't work and can severely affect performance and the warranty on the Clark pump.

[SaucySailoress]

Thanks guys - we're planning on buying one next week when we're in Holland, and at least I have a bit of an idea now what to ask - it's always good to have tips that save me coming off so blonde...

[osirissail]

For many reasons stated by others the best bet is the 12VDC models if your boat is 12VDC. AC models sound good and I have one, but the problem is that a lot of places where you anchor, the water is not good enough to run the R.O. machine. But while underway on a passage, that is the perfect time to run the machine while in clean ocean. The 12VDC units have all the advantages covered.

[Jon Hacking]

Hi Tellie - Thanks for your very specific reply. I've posted most of the details on our Cruising Equipment, Watermakers page. You sound expert enough that I'd appreciate your comments, if you've got the time.

But the short answer is that yes, our system started life as a new Spectra 200C in 2002 & we upgraded it to a 380 by adding a 2nd pump head from another cruiser (which we later found was worn). We've gone round & round with Spectra on this, but we chew through pump heads in ~700 hours, or ~2 years.

Does anyone else here have this sort of problem?

Spectra says that others don't, but they also sell us replacement pump heads at a discount, & I notice that their new design goes with different vane-type pumps, despite them being more delicate (can't run dry), more expensive, & less efficient. Hmmm...

It was Spectra who told us that running both pumps puts more strain (wear) on them. I suggested putting our pre-filters in front of the pumps (I thought sediment in the water might account for the wear) but didn't get a positive reply on that.

Since we only have the flow-meter for the 200, we can't really see our output volume with both pumps running. But we can see our output drop with each pump individually.

You're absolutely correct that the Spectra (& probably most 12v watermakers) are very voltage sensitive. We have 0.2v drop in our wiring, despite going through 3 circuit breakers. Most connections are soldered & my wires are huge, as the watermaker is 30' from my electrical panel. I usually wait until the solar panels have brought the batteries up to 13.9 & the solar-controller starts to regulate. Then I turn on the watermaker for a couple of hours.

We love our Spectra & it generally works well for us, but it does have its foibles (which, I think, is what this forum is all about). Thanks again & all the best!

[foggysail]

Originally Posted by osirissail

For many reasons stated by others the best bet is the 12VDC models if your boat is 12VDC. AC models sound good and I have one, but the problem is that a lot of places where you anchor, the water is not good enough to run the R.O. machine. But while underway on a passage, that is the perfect time to run the machine while in clean ocean. The 12VDC units have all the advantages covered.

Up front--- I am no expert on watermakers, maybe someday I will be. I am now gathering components for one.

But for types of systems, 12vdc will work but it appears it will be very limited unless it is one that uses Spectra's so called intensifier and even that would not be my choice. My point, if the design is going to require a 1HP motor for example, that means 746 watts at 100% efficiency. A 12vdc system is going to demand over 60 amperes. My guess is such a system will make about 20-30 gallons/hr. A 100 ampere hour battery will be completely drained at a constant 1 hour 60 ampere discharge rate. And that charge must be replaced, probably taking hours.

And again, the losses dealing with battery internal voltage drop, connection and wire losses will just add to the total inefficiency.

Now I want to switch to discussing the AC approach which my machine will be. Further it will be powered by a 2HP motor currently sitting in my basement attached to an Arimitsu pump. That pump is going to require energy to output 1.9HP to output 3.5 gal/minute at 850psi. I used the higher 850 psi for power calculations and yes it is a little on the high side but I wanted to be sure the motor was OK. I am targeting 40-60 gal/hr.

I understand the water is purified by the filtering action of the membrane but a quick Google will answer most questions about what can and cannot get through an RO. My point---- it should not matter where the system is used. Sure, the input filters may need cleaning often but that junk is not going to pass through the system.

A follow up with charcoal filtering plus ultrviolet radiation treatment will kill any microbial cells that get through the membrane. When my system is installed, I plan to use it in our local harbors.

Personally, I WOULD NOT RECOMMEND 12 FOR ANY POWER HUNGRY APPLICATION. Just my thoughts--

Foggy

[osirissail]

Forty to 60 gal per hour is a rather massive system by any measure so a significant sized pump/motor would be needed which would need some serious amperage draw at 12VDC. A higher voltage would be both more efficient and probably less expensive.
- - But for average cruising boat a much lower gph is quite acceptable especially with only 2 people on board. The Little Wonder by Village Marine Tec is a 12VDC unit that puts out 6 to 8 gal per hour. The PUR 160 puts out close to 7 gal per hour at 18 amps. These are both regular type high pressure pumps and motors. However, the Spectra units can get up to 40+ gal per hour using 12VDC and 24 amps. But their units are quite expensive.
- - As to where you use the unit, a little bit of oil sucked into the unit from a dirty harbor will take out your membrane quite nicely. But you can purchase a "Mycelx" filter to remove oil from the water - but I don't know how long it will function before it loads up. Then there is just plain mud and suspended stuff in harbors where sewers drain from the village/city. You could go through a serious supply of filters quickly. The rule of thumb I use is if I cannot see the sea bottom in 10 feet of water, I don't run the R.O. machine.

[foggysail]

Yes, 40-60/hr is a lot of water. I have a 100 gallon storage tank and sure, for the two of us that is a lot of water. But I intend to waste much of it.... 2 fresh water heads along with washing down the boat. Our boat sits on a dock most of the time. I am fed up looking at "green stuff" that looks like lettuce coming out of the dock hose. All of our water needs will be processed by the RO. I expect to run the system about every other day. I am also fed up with lugging plastic water jugs in the dinghy.

Yes, I agree that a machine that outputs 6-8 gal/hr would seem adequate. But if you need 5 gallons just for flushing that forces one to run the machine almost 2 hours. No, no, no--- I am not trying to downgrade the smaller machines, I am pointing out things I used in my trade off for my decision.

Seeing 10' down???? Here in New England you will be very lucky to see 4 feet down although in late summer when the water is warmer, maybe 7 feet. It always gets my attention when I visit warmer waters just how far down one can see. Building or purchasing an RO system is one of personal choices based on needs or in my case wants.

Filters--- I expect the first filter one sized at 10 microns or so will need frequent changes. I hope to be able to wash off most of the crude to extend its life. But your right on the mark, dirty water will cause dirty filters.

If 12vdc works for you, and I know it works for many because there are many 12vdc systems out there, then that is all that is important. But folks should consider all options and weigh them against both their needs and expectations.

Foggy

[osirissail]

Don't forget to get/install the "oil removal" filters.
http://www.idswater.com/Common/Exhib...Surfactant.jpg

Go to the bottom of the page to find the cartridge versions. West Marine I think also sells the Mycelx filters which can be used in the standard 9" water filter canister.

[foggysail]

Thanks Osirissail (and I gave you one!).

I will follow your advice!!!!

Foggy

[svcambria]

It was Spectra who told us that running both pumps puts more strain (wear) on them.

I got the same advice for my 380 Spectra (one of the first they made), so I have been running one pump at a time - alternating from run to run. Those little wobble plate heads get expensive. Would love to run both simultaneously without wear issues.
On the PPM issue: back in the Dark Ages (1970s) I worked in Saudi Arabia. My house had two faucets, one had water at about 2000 PPM for washing and the other producing water at about 1200 PPM for cooking and drinking. Everything tasted salty and aesthetically it was unpleasant. But - we frequently had to take salt tablets on top of that to keep blood electrolytes in balance in the 125 degree heat and 99 per cent humidity. My take on this - salt in water is situational and if you sweat you need to replace it.
For the engine running everything - it's great, as long as the engine works - and you are running it anyway. If the engine quits though, there goes the water maker, the refrigeration, the big alternator, and propulsion - which issue do you address first? And it is amusing to watch people run their engines in marinas equipped with AC power because they need the auxiliaries.

Michael

Note: with Spectra and an unchlorinated source of fresh water, you can feed the pumps with the fresh water to clean the water up and the production rate is pretty impressive - 20 g/hr or more

[witzgall]

If you are considering running a WM while at dock in a marina, I would forget that. Every marina I have been in has water that is polluted to some extent. Oil, illegal pumping overboard, paint thinner, etc. I don' t think any watermaker, or the owner for that matter, would last too long.

Chris

[Yohelah]

<"... We've gone round & round with Spectra on this, but we chew through pump heads in ~700 hours, or ~2 years. Does anyone else here have this sort of problem?">


Everyone does.

Short pump head life is a well known problem with the dual pump Spectra's. Spectra actually had the pump head re-designed by Shurflo years ago to include metal parts and a one part shaft instead of the original plastic and pressed shaft.

Spectra also says that pump head life is more than doubled by running one pump at a time. The problem is two parallel pumps fight each other unless they are in sync. You can hear the pump sound change as they cycle through being in sync and then out of sync. A friend who is an engineer and into hydraulics tells me the output needs to be attenuated, we concluded dumping the output of each pump into it's own filter so they stop fighting each other would solve the problem. Also decided it was too much effort to try, so don't know how much it would change things.

Having said all that, is it really a problem? Rebuilding two pump heads every 700 hours doesn't sound that bad to me. Rebuild kits for the pump heads are a little over $70. I have a mag-drive Catalina and the pump head has to go back to Spectra for rebuild, cost is $300. In the past four years I've gone through 3 pump heads on my Catalina. The vane pumps do not like dirty water, notice that the MKII versions of both the Catalina and Newport protect the mag drive pump with the five micron filter and use a boost pump to decrease suction.

I've installed 2 Shurflo's parallel with my mag drive pump so I can run the watermaker as a Catalina with the mag-drive pump or as a '380C' with the two Shurflo's. This is much more robust since the Shurfolo's are not affected by dirty water. Since making this change we've run the watermaker with the two Shurflo's 95% of the time.

If I rebuild the Shurflo's every two years I'll be perfectly happy.

Rob
Yohelah