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Thread: Master/slave

  1. #1
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    Master/slave

    Hello everyone I am new to site. I have visited many times great site.
    Ok I have two 30ra 030 aqua snaps. They both have MBB version 4.0. The problem is that my control point is getting down to 32 or so degrees because it is looking the common dual sensor and the other chiller water temp that is not running and compensating for the water temp difference in the two. The maste slave is not working correctly. I have been on phone with carrier tech support for hours the above is what they said. Any ideas on what to do. Thanks guys

  2. #2
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    La.
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    Page 26 of the install/ service book that came with the unit. Labled configuring and operating dual chiller control. This is where you will find how to set up the units. Make sure that units are piped correctly, in parallel config. Then check common sensor location and make sure that you are reading correctly the water temp. One chiller must be master, and has the common water sensor. Then the two chillers are connected with the CCN bus. I have done this many times and it always works. The only problem ever was when the welders put the common sensor location in an air pocket in the piping. The master chiller makes runs like normal until it sees that the load is being lost, then the other chiller is called on by the master.

  3. #3
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    I have got it set up correctly i believe. I have contacted carrier and they wa;k through the config tables the problem is that the control piont is floating so much. The set piont is 45. the control piont is around 32 or even lower at times. Carrier said it is the version of the MBB and the way it controls the algr. between the two. Is ther a better way to set these two up. the dual sensor is in the common loop and landed on the master.

    Hope this make sense

  4. #4
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    Quote Originally Posted by Jeremy325 View Post
    Hello everyone I am new to site. I have visited many times great site.
    Ok I have two 30ra 030 aqua snaps. They both have MBB version 4.0. The problem is that my control point is getting down to 32 or so degrees because it is looking the common dual sensor and the other chiller water temp that is not running and compensating for the water temp difference in the two. The maste slave is not working correctly. I have been on phone with carrier tech support for hours the above is what they said. Any ideas on what to do. Thanks guys
    So I take it that this is in a parallel configuration with no isolation valves on the chillers?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  5. #5
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    Yes parallel and it has isolation valves on both Ew and LW

  6. #6
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    Quote Originally Posted by Jeremy325 View Post
    Yes parallel and it has isolation valves on both Ew and LW
    What is your DLWT reading compared to the LWT on the chiller that is running ?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  7. #7
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    LWT=49.9 dual = 54 entering and leaving of other chiller that is not running is 57 my control point is around 32
    Thanks for your help

  8. #8
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    Quote Originally Posted by Jeremy325 View Post
    LWT=49.9 dual = 54 entering and leaving of other chiller that is not running is 57 my control point is around 32
    Thanks for your help
    In theory they should be reading the same . It's trying to compensate for blended water it doesn't exactly know you have iso valves. You have something going on with your sensors is my guess.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  9. #9
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    Ok what would the ISO vavles do? Should I turn the slave valve off and see if dual sensor is the same as LWT

  10. #10
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    Quote Originally Posted by Jeremy325 View Post
    Ok what would the ISO vavles do? Should I turn the slave valve off and see if dual sensor is the same as LWT
    Ok I must have missed something I thought you said you had auto isolation valves on each chiller. And yes close the slave off and see what happens. And what is the unit tripping off on?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  11. #11
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    No it has manual full port ball vavles. The alarm is T116 Sorry for not clarifying the vavles

  12. #12
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    Quote Originally Posted by Jeremy325 View Post
    No it has manual full port ball vavles. The alarm is T116 Sorry for not clarifying the vavles
    How cold is your leaving water getting when this alarm comes in anywhere close to 32?

    You could close the ball valve and see if the alarm goes away and see if your DLWT and LWT match up.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

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