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Moen Flo and water pressure

uscpsycho
5 years ago

I bought a Moen Flo and then realized that it has a 3/4" connection but the main water line to my house is 1" so a reducer would have to be used. If you aren't familiar with the Flo this is it.

On their website Moen tries real hard to convince people that reducing to 3/4" will have minimal impact on water pressure. This is what I was told by support via email: At 60PSI you can get a maximum of 32.6 gallons per minute across the device. The pressure loss at, for example, 10 gallons per minute, is 1.7PSI.

I have no idea what this means for me. Would stepping down to 3/4" noticeably affect my water pressure? I have a tub filler that uses 7gpm and that's the highest capacity fixture in the house. Will I see a difference there or anywhere else?


In a few months Moen is coming out with a model that is 1 1/4" but it will be more expensive than the current model which is already quite pricey so if I had to get the larger one I might just pass on it.


Thanks in advance for any help!

Comments (11)

  • uscpsycho
    Original Author
    5 years ago
    last modified: 5 years ago

    It's copper in the house so I assume it's copper outside where this connects. I attached a photo. It is 1" outside but I'm pretty sure inside pipes are not 1".





  • uscpsycho
    Original Author
    5 years ago
    last modified: 5 years ago

    Here's a chart they sent me showing how the Flo affects water pressure. I'm not really sure how to read it. You're sure I won't see a loss in water pressure if I put this in?

    Would you mind briefly explaining why in layman's terms? Common sense says that if you go from 1" to 3/4" you'd see a drop in water pressure because that's 25% less flow capacity. Is it just that the drop would be so small that it wouldn't be noticeable?



  • weedmeister
    5 years ago

    Pressure and flow are two different things.

    The chart at the left states that if you are flowing 7 gpm for your bath, there will be a drop of 1 psi across the device.

    uscpsycho thanked weedmeister
  • uscpsycho
    Original Author
    5 years ago

    And I assume that a drop of 1 PSI is not going to be noticeable? Sounds like a stupid question.


    What about water pressure to my hose spigots, sprinklers or my utility sink which doesn't have an aerator? Hoses and utility sink are probably higher than 7gpm. Will this negatively affect them?


    Or what if a hose is being used at the same time as the utility sink or tub filler? Might I notice a difference then?


    Thanks for your responses!

  • Jake The Wonderdog
    5 years ago

    As Weedmeister pointed out - it's not that you won't see any pressure drop, it's that you won't notice it.


    It's not a 25% drop in flow capacity... but that's another issue.



    uscpsycho thanked Jake The Wonderdog
  • uscpsycho
    Original Author
    5 years ago

    Then I wonder why they are making a higher capacity 1 1/4" version? Maybe it makes a bigger difference going from 1 1/4" to 3/4"? Or you guys think it's just marketing for less informed people like me who think reducing sounds like a bad idea?



  • uscpsycho
    Original Author
    5 years ago

    I decided to test my water pressure (I didn't know it was so easy) and it's exactly 60 psi. According to what Moen told me, at 60psi I can get a max of 32.6 gpm. And according to the chart above, at 32-33 gpm I will lose 7.8 psi which puts me at 52 psi.


    Based on a several websites I looked at, 50 psi seems to be a sweet spot, so even if I am maxing out the flow rate I will still be above 50 psi.


    If I am understanding this right, I should be totally fine under all circumstances. Correct? What I don't know is if 32.6 gpm is a reasonable limit. It seems like it to me, I can't imagine a situation where I'm blowing through that much water. Is there a scenario where a home would exceed that?

  • weedmeister
    5 years ago

    " why they are making a higher capacity 1 1/4" version? "

    If I were to guess, it would be that 3/4" is fairly ubiquitous for your basic 3br/2bath home less than 50' from the curb. Homes that are farther from their supply in the street may have a larger line coming in, like 1" or more.

  • Shiva Kumar
    3 years ago

    I am seeing 30 psi drop at 2 gpm. When I talked to support they said the problem is that I have 1 1/4 line going into a 1" Flo valve. I disagree with them. I think there is a problem w Flo. Anybody else run into this problem. Moen is sending me a replacement 1" to try out first.

  • Sam Shehu
    3 months ago

    Every home should have one of these devices. I have been alerted to open faucets and also warned about small plumbing leaks BEFORE they became large problems.