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  1. #1
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    Question Distance between pumps run in series?

    I have a geothermal loop (1" PE) which I am running a set of pumps in series to attain head height. I know from general rules of pump piping to leave 5-10 the diameter on the suction side to attain uniform velocity. But cannot find information on a min distance between pumps. I'd like to assume the same 5-10 times diameter. But with space considerations, I'd also like a simple nipple connection.

  2. #2
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    1 times 10 = a 10" nipple.

    Isn't that close enough?

    If configuring is the main obstacle why not pump-both-sides? The pumps don't have to be next to each other. Supply pump / return pump would actually be my preferred way to go about it.

    PHM
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    Quote Originally Posted by mrlegoman View Post
    I have a geothermal loop (1" PE) which I am running a set of pumps in series to attain head height. I know from general rules of pump piping to leave 5-10 the diameter on the suction side to attain uniform velocity. But cannot find information on a min distance between pumps. I'd like to assume the same 5-10 times diameter. But with space considerations, I'd also like a simple nipple connection.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  3. #3
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    Quote Originally Posted by Poodle Head Mikey View Post
    1 times 10 = a 10" nipple.

    Isn't that close enough?

    If configuring is the main obstacle why not pump-both-sides? The pumps don't have to be next to each other. Supply pump / return pump would actually be my preferred way to go about it.

    PHM
    --------
    lol, you got me on that one. A "close nipple" connection would be as close as I would like it to be. This would allow the existing setup to maintain it's current layout without adding some weird bends in the system.
    All the flow centers with dual pumps that I've researched have a puller/pusher pump as you described. So yes, this would be the preferred setup. But that may end up being several hours of rework on the existing lines. If there is no efficiency loss issues or risk of cavitation running them side-by-side, then I wouldn't want to waste the time.

  4. #4
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    in the applications I have for high head domestic re-circ pumps, I have bolted them flange to flange for many years

  5. #5
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    I really think the lessening of flow, if any, created by using a close nipple would be very difficult to measure.

    And really? Are you That close on flow that you can't stand the loss of a few tenths? <g>

    I take it that the partner-pumps are thread connect and not flange?

    PHM
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    Quote Originally Posted by mrlegoman View Post
    lol, you got me on that one. A "close nipple" connection would be as close as I would like it to be. This would allow the existing setup to maintain it's current layout without adding some weird bends in the system.
    All the flow centers with dual pumps that I've researched have a puller/pusher pump as you described. So yes, this would be the preferred setup. But that may end up being several hours of rework on the existing lines. If there is no efficiency loss issues or risk of cavitation running them side-by-side, then I wouldn't want to waste the time.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  6. #6
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    Forgive my ignorance.

    What is the benefit of using 2 pumps in series Vs. one pump with the appropriate head?
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"
    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

  7. #7
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    Often it costs less to use two smaller pumps in series to get your net circuit numbers and it does add at least a degree of redundancy.

    Sometimes you need more flow but not double the head - so two smaller pumps in parallel can be used.

    Sometimes you need more head but not double the flow - so two smaller pumps in series can be used.

    Sometimes doing it all in one pump chart jumps the design up into a much larger frame/style/cost of pump - just to gain a little capacity. Using multiple smaller pumps allows you to avoid that.

    PHM
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    Quote Originally Posted by HVAC_Marc View Post
    Forgive my ignorance.

    What is the benefit of using 2 pumps in series Vs. one pump with the appropriate head?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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  9. #8
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    Quote Originally Posted by Poodle Head Mikey View Post
    Often it costs less to use two smaller pumps in series to get your net circuit numbers and it does add at least a degree of redundancy.

    Sometimes you need more flow but not double the head - so two smaller pumps in parallel can be used.

    Sometimes you need more head but not double the flow - so two smaller pumps in series can be used.

    Sometimes doing it all in one pump chart jumps the design up into a much larger frame/style/cost of pump - just to gain a little capacity. Using multiple smaller pumps allows you to avoid that.

    PHM
    -------
    Thank you
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"
    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

  10. #9
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    You're welcome. Just one more thing to stash in your bag-o-tricks. You never know what may come in handy someday.

    PHM
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    Quote Originally Posted by HVAC_Marc View Post
    Thank you
    PHM
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    The conventional view serves to protect us from the painful job of thinking.

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  12. #10
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    .
    PHM
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    The conventional view serves to protect us from the painful job of thinking.

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