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  1. #1
    Join Date
    Dec 2011
    Location
    New Lenox Illinois
    Posts
    1

    Krack Industrial Refrigeration Defrost Heater Issues

    We are having seroius defrost heater failure on many Krack freezer evaporator defrost heaters. The units are in a 40,000 sq-ft freezer so there are about 14 evaporators here. We have replaced at least 100+ thousands of dollars on the replacement. Krack says it is a humidity issue which is not possible in our view. We believ it is fauly design! Please live me any field examples or feedback you may have? Tim Kramer

  2. #2
    What exactly is the failure? Resistance loads are pretty reliable unless wired wrong, as in Delta or Wye.

  3. #3
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,435
    maybe 208V heaters on a 240V supply?

  4. #4
    Join Date
    Feb 2007
    Location
    Northern NJ
    Posts
    653
    Does the defrost termination work properly? Improperly working termination can cause premature failure of heaters due to unnecessary overheating.

  5. #5
    Join Date
    Dec 2000
    Location
    Flat Rock, NC
    Posts
    463
    I've only had 2 heaters fail on 26 plus coils installed and I think I burned those up on startup due to miswired termination. I know those big coils are a pain to diagnose which heater is bad. I hope units are wired in seperate conduits to prevent wiring screw ups. Does each condenser have only one evap? If more than one evap it must have multiple defrost contactors and be properly terminated ( control each evap). Start by verifing wiring first. Kramer says humidity issue, are the wiring harnesses burning out or the heaters?

  6. #6
    Join Date
    May 2003
    Location
    Utah
    Posts
    733
    Quote Originally Posted by krams View Post
    We are having seroius defrost heater failure on many Krack freezer evaporator defrost heaters. The units are in a 40,000 sq-ft freezer so there are about 14 evaporators here. We have replaced at least 100+ thousands of dollars on the replacement. Krack says it is a humidity issue which is not possible in our view. We believ it is fauly design! Please live me any field examples or feedback you may have? Tim Kramer
    I've had experience in an application where there is very little or no frost on the evaporator....this combined with faulty defrost termination so that when the heaters are energized they get much hotter than designed for since there is no ice to melt...and they cook themselves to the point of burning up.

  7. #7
    Join Date
    Dec 2000
    Location
    Flat Rock, NC
    Posts
    463
    look up heatcraft sdk controls, these will skip a defrost cycle when possible and will pay for themselves quickly. I use these a lot on many brands of equipment with no issues.

  8. #8
    Join Date
    Sep 2011
    Location
    Plainfield IL
    Posts
    101
    I just happened to be up on a lift once when a unit went into defrost. 2 of the heaters glowed cherry red. It turned out the heater were wired in parallel instead of series.

    Check your wiring carefully.

  9. #9
    Join Date
    Mar 2003
    Location
    Cochrane, AB
    Posts
    605
    Quote Originally Posted by Fridge Repairer View Post
    I just happened to be up on a lift once when a unit went into defrost. 2 of the heaters glowed cherry red. It turned out the heater were wired in parallel instead of series.

    Check your wiring carefully.
    Same problem here except it blew multiple holes through the coil.

  10. #10
    Join Date
    Jan 2005
    Location
    Ontario, Canada
    Posts
    84

    Defrost heater failures

    Did you ever get to the bottom of this issue? I have the exact same situation right now with Krack MS evaporators and would like to hear your solution.

  11. #11
    Join Date
    Mar 2003
    Location
    Cochrane, AB
    Posts
    605
    Quote Originally Posted by floodedstart View Post
    Did you ever get to the bottom of this issue? I have the exact same situation right now with Krack MS evaporators and would like to hear your solution.
    The factory wired the heaters wrong, that was the problem.

  12. #12
    Join Date
    Jan 2005
    Location
    Ontario, Canada
    Posts
    84
    sorry mspanky- I was looking to find out what krams problem ended up being.

  13. #13
    Join Date
    Jul 2011
    Location
    St. Louis
    Posts
    121
    A newer system out there cycles the heaters during a defrost based on temperature rise of the coil. This wil avoid the scenario Bunny describs. If there is little or no ice, the heaters don't have a place for their heat to go except to raise coil temps too high. Sure, the terminator will pick it up sooner or later, but if it is on a return bend outside the tube sheet it is likely to be later than sooner. The heaters may also run cooler and last longer in this mode.
    In an infinite universe, not only are all things possible, all things are necessary

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