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Thread: New reverse osmosis system. Flow rate seems low. Please advise

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    DIY Junior Member ribs1's Avatar
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    Default New reverse osmosis system. Flow rate seems low. Please advise

    Hey guys,
    I just finished having a reverse osmosis system installed as part of my new kitchen project.
    I bought a black and white unit from pure water products in texas with a permeate pump.

    Everything is working now but I think the flow rate is too low. I have never had one of these system though so I guess I'm not sure what the flow is supposed to be.

    To test, I filled a 1 quart container in 35 seconds. is this normal? What can I do to increase flow rate from my RO faucet?
    Here's some more details
    1. Unit is mounted on a shelf in the basement just under the kitchen cabinet.
    2. All the tubing is 1/4 inch
    3. The tank is mounted just under the RO system.
    4. I think the membrane is a 24 gallon per day.

    Any other tips would be appreciated.
    Thanks

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    In the Trades Tom Sawyer's Avatar
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    what is the pressure? And...how much water do you expect to get through 1/4" tube
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    DIYer, not in the trades LLigetfa's Avatar
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    RO systems are often placed directly under the sink. You can lose about 4 PSI by having it in the basement. The long run of 1/4" tubing doesn't help. A different faucet might make a small difference.

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    DIY Junior Member ribs1's Avatar
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    Quote Originally Posted by LLigetfa View Post
    RO systems are often placed directly under the sink. You can lose about 4 PSI by having it in the basement. The long run of 1/4" tubing doesn't help. A different faucet might make a small difference.
    The unit is on a shelf high on the wall in my basement pretty close to the ceiling directly under the sink cabinet. I didn't really have much room in the sink cabinet because I have a large apron front sink. I could have gotten it in there though.

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    DIY Junior Member ribs1's Avatar
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    Quote Originally Posted by Tom Sawyer View Post
    what is the pressure? And...how much water do you expect to get through 1/4" tube
    I don't know how much water should come through a 1/4 inch tube. I don't really know how to measure my pressure.
    I guess I could look at the pressure gauge by my well pressure tank?
    Should I change this whole thing to 3/8" tube and fittings?

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    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Quote Originally Posted by ribs1 View Post
    I don't know how much water should come through a 1/4 inch tube.
    One source (http://www.engineeringtoolbox.com/wa...se-d_1524.html) shows a little under 1gpm through 100' of tubing at 40 psi. If you've only got a few feet of tubing I'll bet the limiting factor is the RO unit itself.

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    In the Trades Tom Sawyer's Avatar
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    Somewhere in the paperwork that came with the unit there should be a chart that shows the volume / pressure chart etc for the unit.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    That's all folks! Gary Slusser's Avatar
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    Doesn't seem to be anything wrong except customer volume expectations are not met.

    The size of the tubing or the basement install is not a problem.

    There is no way you can lose 4 psi in the distance from the basement to the faucet on the kitchen sink counter, well a kink in the tubing would do it but not by the length or dia/size of the tubing.

    Most under sink ROs I am aware of use 3/8" tubing from teh tank to the faucet but..... You can not use larger dia tubing and get more water because the faucet is 1/4" and the captive air pressure in the RO storage tank provides the pressure to the faucet which should be about 7-10 psi.

    The RO has to work against that pressure so you don't go any higher without severely decreasing the output volume of RO water and the time it takes to produce it.

    To get more product water in a shorter period of time you'd need a larger than 24 gal/day membrane. Or to add a pump.

    In the manual there should be instructions on how to check that air pressure. You do it with a regular tire pressure gauge and with no water in the tank.

    The well pump pressure switch setting has nothing to do with the pressure coming out of the RO's storage tank.
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