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head loss through swing flow check versus spring check

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Brad White_203
Brad White_203 Member Posts: 506
in THE MAIN WALL
Just to be clear, the functions are a bit different, with a swing check preventing back-flow when two pumps are in parallel and the spring or lift-check doing the same thing but also holding back most gravity flow.

IOW: I would not substitute a swing check for a lower PD if it gives up the essential function.

Now, your question: It really depends on the manufacturers' data, but your inclination is correct.

My tables have a swing check in one-inch size being equivalent to 10 feet of pipe. A lift check is said to be equal to a globe valve, so that would be 29 feet, call it 30.

If your flow friction rate is say, 3 feet per hundred feet, that works out to 0.30 feet for the swing check and 0.90 feet for the spring check.

Just keep in mind what you need it for. If a thermal trap might work better, maybe consider that, but sometimes a good spring check is just the right thing to do.

Besides, in the scheme of things, look at the pump curve and see what difference in flow would occur using one, the other or none. Flow is a very forgiving variable regarding heat output.

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  • SciGuy
    SciGuy Member Posts: 15
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    Look for lowest head possible - Swing versus spring flow checks

    We are attempting to reduce the total head of a radiant system to the least possible value in order to use the smallest most efficient pump possible. I have not had too much luck finding data on 1" swing check (Nibco) versus spring checks like the B&G Flow-check flange units. My intuition is that the swing check should be a good bit lower head but would like confirmation from those with more experience.

    Thanks for any informed replies,

    Hugh
  • SciGuy
    SciGuy Member Posts: 15
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    Thanks Brad

    The system is a TT Prestige Solo 60 driving a very simple single loop (no primary secondary)as well as a second circulator supplying a small Mega-Stor indirect. We need to prevent back flow through the indirect as well as the main loop.

    Thanks for the input.

    Hugh
  • Brad White_202
    Brad White_202 Member Posts: 105
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    Hey, Hugh-

    You got a 60!

    Great- Let us know how it works out.
  • Tony Conner_2
    Tony Conner_2 Member Posts: 443
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    If You Don't Have...

    ... enough pressure drop across your check valve, the flow won't drive it open, and hold it there. It'll flap like a flag in the wind, and wear out long before it's time. Check valves are similar to control valves, in that they're very often one pipe-size smaller than the correctly sized line in which they're installed.

    The attachment is from the Crane Technical Paper No. 410.
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