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  1. #1
    bazobeleza's Avatar
    bazobeleza is offline Registered User
    Location : faro, portugal, & Liverpool for my sins, this year more portugal than l'pooll
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    Default watermakers from Jetwashers

    Being a Yorkshireman, inveterate tinkerer and all round tight git, I have decided to build my own watermaker. I have investigated this on the net its well documented, I find I can build a 40gph one for for about 1500 but........ I then heard about a dutch lad selling plans for using a jetwasher for the base but of course he wants his palm crossing in Guilders before he'll send you the plans.

    My question is has anyone recently made a watermaker using a Karcher or similar and how did it perform.

    I have a Karcher K7 that is surplus to requirements and needs a new hose has a performance spec about 3.75hp motor and 550l/hr (120 gph) at 2300psi so I think with a different (lower) pressure regulator at 1500psi the output could be increased probably to around 200 gph and a 12% conversion rate would give a watermaker of 24gph capacity

    The mechanics of construction appear to be straightforward high pressure plumbing. There does appear to be a problem buying the RO pressure vessels in the UK as I've not yet found a supplier.

    Input power isn't an issue, cost however is. Any advice will be gratefully received particularly on sourcing the RO bits in the uk.
    happiness is a 10kva genset and cold beer

  2. #2
    pvb's Avatar
    pvb is offline Registered User
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    I'm not sure that Karcher motors are designed for continuous operation - I've certainly experienced thermal cutout on mine during fairly heavy use. Apart from which, I don't think the pumps are very durable, especially if pumping seawater; it would be a shame to go to the trouble of building a watermaker and then finding that you have to rebuild the pump every few hours.

  3. #3
    Chalker is online now Registered User
    Location : West Berkshire
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    I've seen this proposed before and seen statements that the pumps corrode with salt water, also seen suggestions that if you produce lots of fresh water you can flush the pump with some of the fresh, doesn't need to be musch or at high pressure and gives the RO a flush as well.

    Try Atlantis Marine in Plymouth for RO parts. They were very helpful each time I've called.

    My local goods vehicle high pressure hose people were also very helpful.

  4. #4
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    Default

    This company may be interesting


    http://wolfhartindustries.com/
    I'm more Teddybear than Werebear
    Beware the Grizzlybear

  5. #5
    nimbusgb is offline Registered User
    Location : A long way from my boat! :(
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    A Karcher type pump ( medium duty one ) outputs at around 20 bar, the pressure required to get a RO membrane to work with salt water is 800 to 1,180 psi or 60 to 80 bar.

    If you buy one of the High end professional pumps from Karcher you end up paying the same as a proper pump and it's still not a stainless steel one.

    The high pressure pump is the heart of the system, best to bite the bullet on it's purchase.
    Last edited by nimbusgb; 05-05-12 at 14:08.
    "Tomorrow to fresh woods and pastures new"

  6. #6
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    I managed to find a CAT 277 pump on Ebay for 300 new. Perhaps look there?

  7. #7
    electrosys is offline Registered User
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    Brent Swain has been successfully using a PressureWasher-based Watermaker for several years. There are 2 quite different types of pumps used in Pressure Washers - one aluminium, one stainless steel/ceramic. No prizes for guessing which one he uses.
    Can be contacted via: http://groups.yahoo.com/group/origamiboats
    Last edited by electrosys; 05-05-12 at 14:27.
    te nunquam solus schizophreniae cum

  8. #8
    Reverend Ludd's Avatar
    Reverend Ludd is offline Registered User
    Location : Great Yarmouth, Norfolk
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    This might help http://www.ro-man.com/
    Don't believe everything you read on the internet - Abraham Lincoln.

  9. #9
    bazobeleza's Avatar
    bazobeleza is offline Registered User
    Location : faro, portugal, & Liverpool for my sins, this year more portugal than l'pooll
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    Thanks all, there's some very useful sites and info, it will make my job that much easier. I'd looked at the cat pumps but never thought of ebay as a source. Just got to get the kit together now and get it built.
    happiness is a 10kva genset and cold beer

  10. #10
    Sybaris's Avatar
    Sybaris is offline Registered User
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    Check this thread:

    http://www.ybw.com/forums/showthread.php?t=299510

    I explain my experience with a Karcher setup (bought from a Dutch guy incidentally) in message # 11.

    Cheers,
    Per

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