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captden 02-13-2010 01:05 PM

PRO Watermaker
 
Next project is the watermaker. I've been looking at all the watermakers trying to deciede if I should build my own or buy, and while searching I came across the PRO 500 GPD watermaker and the price is very attractive. Does anyone hear have any experince with these watermakers.

Thanks
captden

sailingdog 02-13-2010 04:50 PM

Not really suitable for use on a sailboat IMHO, since they require a fairly high amperage 110 VAC source.

captden 02-13-2010 08:14 PM

Are you saying that it draws more current than the most common ones that are on the market? The plans I have looked at to build your own have the same size pump and motor. I'll be using it when I'm running the generator to charge the batteries and I don't think any units that are powered by dc will give you 15-20 GPH.
captden

sailingdog 02-14-2010 07:50 AM

No, what I am saying is that these units require a fairly hefty AC system, and most small sailboats do not have the electrical capacity to power them for any period of time reasonably. The Pro 500 draws 15.2 AMPS @ 110 VAC... if you need an inverter for that, you're looking at about 150 amps. IMHO, you'd need at least a 2 KW generator to properly feed the watermaker.

Most people who want a watermaker aboard their boat want one to help make the boat more self-sufficient and extend the time between marina visits. A watermaker like the Pro 500 doesn't really do this, as it increases your dependence on fuel for the generator. A smaller RO unit that is more closely matched to your actual needs would probably make more sense. Not only would you run it more often, which helps prevent the membrane from getting contaminated, but it would use far less electrical power, and might be usable using passive electrical generationólike wind and solar.


Quote:

Originally Posted by captden (Post 570037)
Are you saying that it draws more current than the most common ones that are on the market? The plans I have looked at to build your own have the same size pump and motor. I'll be using it when I'm running the generator to charge the batteries and I don't think any units that are powered by dc will give you 15-20 GPH.
captden


captden 02-14-2010 09:32 AM

[quote=sailingdog;570107]No, what I am saying is that these units require a fairly hefty AC system, and most small sailboats do not have the electrical capacity to power them for any period of time reasonably. The Pro 500 draws 15.2 AMPS @ 110 VAC... if you need an inverter for that, you're looking at about 150 amps. IMHO, you'd need at least a 2 KW generator to properly feed the watermaker.

Sailingdog: Your right the 500 is not advisable on a small boat with limited power. I think trying to run it from an inverter wouldn't cut it. The 12 volt units I have looked at draw an avarage of 15 amps dc that will give you around 5 gph. If I ran the unit without the gen running you will really use amp hrs. in a hurry. The boat I'm installing the water maker is a 50' and has a 7kw generator. My thinking is if I charge the house bank every other day for a couple of hours I can make about 20-30 gals. From what I've read the 500 draws 15.2 amps FLA I think that means full locked rotor current. After the initial start current surge I think the total draw will be under 10 amps which is no problem for the generator.
Thanks for the info you made a lot of valid points. Where in New England, we sail out of Winthrop just outside of Boston Harbor.
captden

sailingdog 02-14-2010 09:58 AM

I sail out of New Bedford harbor. I'm behind the Hurricane Barrier. :)

On a 50' boat with a 7 kW Genset, then you should be okay. Remember that you'll want to backflush the membrane with RO water each time you shut the unit down, unless you're not going to be using it for more than a few days, in which case you'll probably want to pickle the membrane.

I'd also recommend plumbing in a separate tank that you fill only with RO water that you can use to back flush the RO membrane. The reason for this is simple—chlorine will destroy the RO membrane, and if you accidentally flush the system with non-RO water, you stand a really good chance of destroying it, since most municipal water systems use chlorine. This also allows you to test the output of the watermaker before transferring it to your main fresh water tanks.

GaryHLucas 02-14-2010 07:52 PM

FLA means RUNNING current! Starting current will be 3 to 6 times that, hence your 7 KW generator will notice when that sucker starts. Some of the RO units on the market that use very low power are able to do so because they recycle the high pressure. They can make water for as little as 1 amp hr. @ 12vdc per gallon!

The advice about only using RO water for flushing is very important, as chlorine WILL kill the membranes quickly. In my job I design and build RO units for wastewater. A whole lot of other issues there.

Gary H. Lucas

foggysail 12-04-2010 08:06 PM

As the song says-- "its been a long, long time from May to September" and here it is from February to December.

ANY THING NEW WITH DIY WATERMAKERS???

Foggy


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