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CV?

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Jamie_6
Jamie_6 Member Posts: 710
in THE MAIN WALL
Would someone please explain to me what CV is and its importance to a hydronic system?

Jamie

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  • George Peteya
    George Peteya Member Posts: 34
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    Cv

    Jamie, Cv is the flow rate in gallons per minute at which the pressure drop is 1 psi (2.31 feet of water). You use this value to size mixing valves, for example. To get good control, you want the pressure drop through the valve to be at least 1 psi. So if your zone flow is 8 gpm, look for a valve that has a Cv of 8. Use a valve that's too big (high Cv), it "hunts" and you get poor control. Too small (low Cv), and you wonder why the zone doesn't have enough flow. Hope this helps.
  • Riles_3
    Riles_3 Member Posts: 60
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    The best possible

    explanation will take place at ROBERT BEAN's seminar on April 22nd for the RPA-WAC (Washington DC Area Chapter).

    The seminar will take place in Northern Virginia. A resonable ride from Philly.

    Email me at jriley@tsomerville.com and I will make sure you get details.

    Jeff "Riles" Riley
    Thos. Somerville Co.
    2004 President RPA-WAC
  • Tom Meyer
    Tom Meyer Member Posts: 300
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    Cv

    The flow rate of 60°F water through the valve (in GPM) that produces a pressure drop of 1 PSI.

    As the valve stem is closed, the Cv decreases.

    Tom Meyer
    Senior Designer/Trainer
    Precision Hydronics Corp
    www.precisionhydronics.com

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  • ken D
    ken D Member Posts: 60
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    Primary-secondary pumping made easy

    Primary-secondary pumping made easy, get Dan's book, it explains all about it, in plain, simple english! And what's best of all, is that he thoroughly goes through several scenarios unlike other books that assume you know whats going on after the first example, but he repeats the information over and over, and it gets into your head that way, soon, you will own it. Get this book! Get the knowledge and wisdom to know the ins, outs, hows and whys of what you do for a living, and enjoy it everyday.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
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    Well said Riles

    I'll be there, and I'll bring my cv with me. WW

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  • Tim Doran_2
    Tim Doran_2 Member Posts: 131
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    The trick

    Is understanding the result of component selection on system performance. Friction loss is not a lineal thing it is a square function therefore it is important to figure out what is going on. When you have a known Cv and known(desired) flow it is pretty straight forward. A B&G System Syzer, scale 5 makes this a snap. Call if you need help, I am in my office for a while today or try my cell phone.
    952-997-5334
    612-865-6059


    Tim D.
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