Ro Unit Advice

Discussion in 'Water Fed Pole Cleaning' started by Oliver, Apr 11, 2013.

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  1. Oliver

    Oliver Well-Known Member
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    Hi all,
    I don't know much about ro's, but I have a merlin in a flight box with a di & what I believe is a salt softener which I got for free, I never used it as I knew the membrane etc. need changing so I just pinched the di & used it as a second one in van.
    I use a 5 stage small ro no idea if its a 50 or 300 a day unit lol which is now coming out at 67ppm.
    My question is do I get the merlin going or replace membrane etc. in small one?
    I know it will probably cost more to get merlin going but is it worth it for me? as I filter into 2 1000 ibcs & pump it out when needed.
    Also are all the small ro's same size i.e. 10 inch or & I talking rubbish as I wouldn't know what to look for on the smaller one?
    many thanks for any help
     
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  2. spruce

    spruce Grand Master
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    Merlins use a lot of water, have a poor efficiency but produce water quickly. As they are primarily an under counter kitchen purification unit, they switch the inlet water off when the tap (pure) is switched off. So an ordinary stop **** on the side of an IBC tank will suffice. They also need an additional sediment filter before the chlorine block.

    The small membrane RoMan type R/Os are much more efficient but produce less water.

    We had 1 of the RoMan filters. It had 3 membranes which we uprated to 150 GPD each (so 450GPD). It worked fine for the 2 of us using 1 IBC tank - I drew water in the evening and son in the morning. Now there is 3 of us we have replaced this with a 4040 as the 450 wasn't keeping up. (We regulate ours through a Solenoid valve and float switch. When pure water is taken it will automatically start the filter process and switch off once the tank is full. We don't need to monitor it.)

    In our area we have an inlet TDS of 115. Our 4040 brings it down to 2ppm on 40psi with no booster pump - HF5 membrane. A fellow window cleaner just down the road has had 2 Merlins. The current one is producing 10ppm with the same water.

    Our 4040 runs at a waste to pure ration of 55/45. His Merlin runs at about 5 waste to 1 pure.
     
  3. Oliver

    Oliver Well-Known Member
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    Thanks Spruce, I forgot about the RO man, I've just been on his site & found some useful info on the basics of how they work.
    I didn't really think about the efficiency side of how much waste is produced!
     
  4. spruce

    spruce Grand Master
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    Unfortunately waste water is expensive if you are on a meter. For a single operator, I think the 4040 is a bit over the top. I seriously consider a 2020 through. Alex Gardiner has a good modular system on his site which will run at a pure to waste of around 1 waste to 1 pure.

    Filling 2 empty ibc tanks allows the r/o to run much more efficiently than if its stop/start. It certainly takes a few minutes after starting before the r/o is running at a tds of 2 in our case.
     
  5. Oliver

    Oliver Well-Known Member
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    Both places I fill my tanks are not on a meter, I am still confused what to do for the best!
    Can anyone tell me what the blue di is for & what looks like a salt vessel? is or is for?
    I don't know if this is worth keeping or is its worth anything to ebay as spares?
    IMG_0648.JPG IMG_0632.JPG
     
  6. spruce

    spruce Grand Master
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    Its very difficult to work out what these items are.

    You need to start at the R/O connections and work backwards.

    According to a manual I have found the Merlin has a 4 barrel manifold. The top connector is for a flush tank which is optional. This connector is marked O. The inlet feed is the next and marked with an arrow. The 3rd is the Concentrate (waste) and in marked with a triangle. The 4th is pure and marked with a square.

    So from the picture it looks like the top connector coloured blue with a small diamt pipe goes to a flush tank. The second connector down looks like it has a red pipe into it. It looks like it comes from the blue filter housing on the right back of the photo. I would suggest this is a sediment prefilter. So this means that the pipe into the prefilter is the water inlet which is the hose connector on the left. To identify the pure follow the bottom connector from the Merin. It should take you to one of those 1/2" hozelok connectors. The pipe from the other Hozelok will be your outlet to the tank. Those 2 Hozelok connectors will fit onto a small DI vessel which is missing. The di vessel will be where your resin goes. A di vessel to fit in there is going to be very small and won't last long. I would suggest you couple those 2 Hozeloks together with a male joiner and buy a bigger vessel and fit it into the line (pipe) to your IBC storage tank.
    The last coupling will be your waste.
    I would take a stab that the pure outlet is the center nozzle and the waste is the right one of the three.

    You could run it and see what happens. The flush tank was designed to build up a water pressure with pure water and when the Merlin switches off, it would back-flush the membranes.

    http://www.rotogo.co.uk/ro-installation.php

    http://www.rotogo.co.uk/
    search for installation manual
     
  7. Oliver

    Oliver Well-Known Member
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    Many thanks for your advice & the link, I think I will connect it back up like you say & see. Thanks again
     
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