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  1. #1
    Join Date
    Jul 2006
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    Primary loop and secondary loop

    I am taking engineering classes at school, can someone please explain to me the primary and secondary loops for a chiller system-- please see my attachment. Also the glycol loop-please see my attachment. Thx guys.

    My email address is:
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    Last edited by BaldLoonie; 03-26-2010 at 07:20 AM. Reason: please put e-mail address in your profile

  2. #2
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    Dec 2008
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    Bell and Gossett's website has a great technical section that explains the basics of primary/secondary. Your best bet would be to start there. It was set up for just the purpose of what you're asking. Don't know what you're asking for on the "glycol loop" - couldn't see the attachment very well, but there may be something there for it as well. I can tell you after looking at the first attachment that I'm not too much in agreement with the author of that book and the terminology he/she uses. One of those is actually a primary/secondary/tertiary system (without secondary loop loads), one is a primary/secondary, and one is a pure primary loop system (going from bottom to top).

  3. #3
    Join Date
    Apr 2004
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    566
    http://www.kele.com/templates/content.aspx?id=4946

    Above is a link to an article that gives various circumstances present in variable primary systems(not the same as primary secondary)but is a good read,i would read bell and gossets stuff first.

  4. #4
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    Aug 2002
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    Engineering School.

    Search for “Honeywells Building Controls”.

  5. #5
    Join Date
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    Western Wa
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    Parallel loops is what it is. The initial design will make or break it. GPM's and head.

    Each one you see will be different. One of the most common problems is wrong way flow in decoupling bridges. That typically first shows up in low return temps.
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  6. #6
    Join Date
    May 2008
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    Central Pennsylvania
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    Quote Originally Posted by Randy S. View Post
    Parallel loops is what it is. The initial design will make or break it. GPM's and head.
    True to that, and they can be real hard to get working right if the design is off and the building is up and running!

    Randy, I have never heard the term "decoupling bridge", can you educate me?

  7. #7
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    Western Wa
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    The term "decoupling bridge" is engineereze for the piece of pipe that is common to both loops. In a decoupled central plant layout, that would be at each individual building in the system. A lot of people use a check there or maybe a circuit setter. You'll see it all sorts of different ways. Sometimes just wide open. Maybe variable speed pumping, or even a combination of everything.

    It is an often overlooked path for flow from supply to return, when chasing balance or low plant return temp problems.
    God Bless our Veterans

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  8. #8
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    May 2008
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    Central Pennsylvania
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    Ok thanks, I know exactly what your talking about now, just never knew the correct engineering term I guess. Now I can't wait to use that one on monday.

  9. #9
    Join Date
    Jul 2006
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    30
    Could you please provide me with a link, I went to Bell and Gosset's website, searched under Literature and Technical Help, did not find a tutorial on primary and secondary loops. Thx.

  10. #10
    Join Date
    Apr 2004
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    Maybe since your in engineering school it might make good practice to find the information.

  11. #11
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    that B+G is some seriously dry reading. Really gotta keep your eye on te prize to get through that lol. I'll have to read these a dozen times each....

    great tech stuff though.
    Guinness for strength

  12. #12
    Join Date
    Dec 2008
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    Dixiana, AL
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    Quote Originally Posted by B_roche View Post
    that B+G is some seriously dry reading. Really gotta keep your eye on te prize to get through that lol. I'll have to read these a dozen times each....

    great tech stuff though.
    Learning the in-depth technical aspects of almost any subject along the lines of things that we work with can get pretty boring, but it's taking the time and putting in the effort to make that knowledge as second nature as breathing that separates the wants and the cans.

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