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  1. #1

    Hussmann low temperature island defrost adjustment

    Dear fellows:

    Im having some problems keeping the proper temperature in a new Hussmann ISF low temperature island. The unit is used for frozen packaged fish steaks. Most of the time, the steaks are rock-solid frozen, but recently Ive noticed that the upper layer of the packages softens a little bit. Im using four defrosts per day (one every 6 hours) with a 30 minutes failsafe adjustment. The defrost termination is by evaporator pressure, and its adjusted at 80 psig for R-22 . According to my data logger, the temperature at the product level gets up to 36 F during defrosts, and it takes almost two hours from defrost initiation to recover to 6-8 F. Does all of this sound normal or am I doing something wrong?
    One thing Ive noticed is that the defrost heater is not embedded in the evaporator coil, but it is located next to it, in the air flow duct, so that in order for the evaporator to defrost, the fan must be kept running as to force the heated air over the evaporator. Strangely, this heated air also circulates through the product section during defrosts. Couldnt this defrost method lead to a little thawing of the merchanside?

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,085

    coldkeeper...

    If you don't have it already, here's the manual for that series of cases:

    http://www.hussmann.com/docs/inst_ma..._ISM_06_im.pdf

    They call for only two defrosts per day. If you had to add the two defrost periods due to icing problems, you may want to verify that the store conditions don't exceed 75F and 55% RH and that there's no air movement around the case. These little buggers aren't very forgiving from that aspect.

  3. #3
    Join Date
    Sep 2005
    Location
    florida
    Posts
    5,495
    Quote Originally Posted by icemeister View Post
    If you don't have it already, here's the manual for that series of cases:

    http://www.hussmann.com/docs/inst_ma..._ISM_06_im.pdf

    They call for only two defrosts per day. If you had to add the two defrost periods due to icing problems, you may want to verify that the store conditions don't exceed 75F and 55% RH and that there's no air movement around the case. These little buggers aren't very forgiving from that aspect.
    I agree with ice you should only need 2x a day defrost if everything is
    else is good such as the a/c system and have you checked superheat?
    I love the smell of phosgene first thing in the morning:

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  4. #4
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    when I pull in the driveway at night for the weekend, typical night like tonight, and have to think of Hussman's dumb a$$ ways, it just makes me ticked off. LOL.

    These *&(*H{UDH{(* things are very touchy. Smoke the case. Your air flow is screwed up. The airflow on these has to be perfect. I just got done friggin with one of these.

    I hate this company. Every day I find a new way to hate them. I think they are the poorest of all of the manufacturers.
    People who think they know everything are a great annoyance to those of us who do.

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