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  1. #1
    Join Date
    Mar 2016
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    Marengo, IL
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    RTHB momentary loss of power, transition compete input open.

    Have used this site for years for information but its my first time posting so forgive me if I'm in the wrong area. My company (Althoff Ind.) has serviced an account with an RTHB450 for multiple years. I have just taken this account over from our previous lead tech this year and I've found several issues that were "addressed" but never really corrected. The chiller has had continual random trips on transition complete input open (will run for a week to 3 weeks without issue), and started to develop issues with momentary power loss at the end of last season. I've not actually seen either of these faults occur while on site. The AUX on 2K2 has been replaced multiple times to try and resolve the issue, why we keep replacing the same part and hoping for a different outcome baffles me. The operator interface and the UMC starter module were also replaced 2 years ago, still the same problem. From digging into this I'm seeing that others have had issues with failing HPC's that cause random faults in starters, and I can see how by looking at the schematic in the IOM. I'm planning on replacing the HPC to eliminate that as a possible cause but am fearful I may be overlooking something. Any advice on what else to check? Again, I've not actually seen any of these faults occur while on site, always starts fine for me when I'm there.

  2. #2
    Join Date
    Jan 2004
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    PA
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    Moved to Chiller forum.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    99% of the time, it is going to be an auxiliary. but the HP switch could be an issue. also, check for loose wire termination connections.
    Don't step on my favorite part of the Constitution just to point out your favorite part.

    Political Correctness is forced on you because you have forgotten decency.

  4. #4
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    I once found an early model RTHB that had a slightly high setpoint on the cooling tower fan. Sometimes entering condenser water temp would get high enough to cause some chiller vibration, which would cause that HP switch to chatter, shutting down the chiller on Momentary Loss of Power.

  5. #5
    Join Date
    Mar 2016
    Location
    Marengo, IL
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    Thread Starter
    Thanks for the info. Just got approval from the customer to replace the HPC. Going to give it a shot and see.


    Sent from my iPhone using Tapatalk

  6. #6
    Join Date
    Mar 2016
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    Marengo, IL
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    Thread Starter
    Quote Originally Posted by Nuclrchiller View Post
    I once found an early model RTHB that had a slightly high setpoint on the cooling tower fan. Sometimes entering condenser water temp would get high enough to cause some chiller vibration, which would cause that HP switch to chatter, shutting down the chiller on Momentary Loss of Power.
    How high of a set point are we talking?


    Sent from my iPhone using Tapatalk

  7. #7
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    Quote Originally Posted by Dcoursey86 View Post
    How high of a set point are we talking?


    Sent from my iPhone using Tapatalk
    The indicated setpoint on the control was 85. But in reality, water temp would sometimes get above 90, and you could hear the chiller begin to sound like it was under a strain. And then, sometimes water temp would get even higher, and the chiller would vibrate and shut down on Momentary Loss of Power.

    I was there with the contractor who had it under contract. When I told him what I believed the problem was, he said they'd take care it. I never saw that chiller again. I heard they replaced the tower fan controller, and never heard of any further problems.

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