The Lowdown on Low Ice Production

March 2, 2001
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The ice machine owner calls you with an all-too-common complaint: “It’s making ice, but it just won’t keep up.”

It is possible that the machine needs a really good cleaning. Or, the unit may be undersized for how much it is used and what the temperature around it may be.

When you arrive at the jobsite, first do a quick visual inspection of the unit. Look for signs that normal maintenance has not been performed; this can seriously affect ice production. Remember, regular maintenance really pays big benefits towards better efficiency and maximum production.

Generally, manufacturers recommend a service schedule that includes cleaning the water system with an acid-based ice machine cleaner and sanitizing to eliminate bacteria. Annual cleaning is usually recommended.

However, additional regular service may be required in areas with bad water.

Cleaning instructions are usually located on the cleaning label and/or in the instruction manual that comes with the unit. Be sure to follow the instructions and use the cleaner recommended by the manufacturer; this will protect a plated-type evaporator from damage due to harsh chemicals.

Inspection CHECKLIST

  • Check water system and evaporator for scale buildup. Clean as necessary.
  • Check for talc or mineral buildup in the reservoir. Remove and flush thoroughly.
  • Check pump motor operation. Look for a broken impeller or slow pumping.
  • Check water flow through the external water filter. You are looking for low water flow to the unit.
  • Check the strainer, the inlet water valve screen, or the float valve (if used) for obstruction.
  • Inspect the float valve assembly adjustment and operation (if used).
  • Check the air filter and condenser fan blade and coil for dust and grime.
  • Check for proper drainage or water backup in the bin that can melt ice away.
  • Inspect for water overflow in the reservoir that washes ice away.
  • Check the bin control for proper location and operation.


  • PRODUCTION CHECK

    Once you have inspected the unit and cleaned it as necessary, determine if there really is a problem by conducting a production check.

    You will need to time a complete cycle, from the beginning of one freeze cycle to the beginning of the next. You will need to catch the ice produced during this cycle and weigh it.

    The formula for checking ice production is to divide the cycle time (in minutes) into 1,440 min to get the number of cycles the unit will run in a day. Then multiply the number of cycles by the ice drop weight (in pounds) for the total ice production in 24 hrs.

    1,440 ÷ Cycle Time X Ice Drop Weight = Production

    While you are waiting for the cycle to complete, check the manufacturer’s data on that specific model number to determine what the production should be. Data charts are generally available to show production, ice drop weight, and approximate cycle times under a variety of conditions.

    You will need to know the incoming water temperature and ambient temperature around the unit to cross-reference the data chart.

    Once the production test is completed, compare the results with the manufacturer’s data. If the amounts are close, that is likely all of the ice that will be produced by that machine in one day.



    WHERE’S THE ICE GOING?

    At this point you will want to discuss where the ice is going. Determine the approximate ice needs by asking a few questions. Make a list of what the ice is used for and the approximate amounts. Add a 25% fudge factor and compare it to the present supply.

    If the production is inadequate, seize the opportunity to sell the customer a larger ice machine.

    It is possible, however, that the customer may have the appropriate machine production but does not have enough storage to get through heavy-use periods. In this case, there are usually two choices. They can bank ice in bags in the freezer for hot days, or change to a larger storage bin.

    If the production is not within the manufacturer’s specifications, it’s time to check the refrigeration cycle.

    Most ice machines use a standard thermostatic expansion valve system. These ice machines have a critical charge system for maximum ice production. The refrigerant type and correct charge are usually listed on the unit nameplate.

    The key to proper production is proper cycle time. The freeze and harvest times should closely match the manufacturer’s specifications for the air and water temperatures at which you are operating.

    Remember that while all ice machines perform the same function, the operational sequence varies between manufacturers. Cycle time also varies. Some manufacturers prefer long cycle times while others prefer short cycle times. Know your products well enough that you can spot a problem if it exists.



    SYSTEM CHECKS

  • If the evaporator and condenser are clean and a charge problem is suspected, read the nameplate charge type/amount and weigh in correct type/amount.
  • Check system pressures against manufacturer performance data.
  • Inspect the evaporator’s frost pattern and freeze cycle time for proper expansion valve operation.
  • Check ice fill on the evaporator. Look for full, normally shaped cubes from top to bottom.
  • Check compressor efficiency by the compressor manufacturer’s amperage curve. The pumpdown method is not recommended.
  • Check the hot gas system for proper operation. No hot gas should leak through the hot gas valve during the freeze cycle.
  • Look for proper operation of additional refrigeration components such as headmaster valve, bypass-cooling valve, liquid line valve, etc.
  • Look for proper pump motor and fan motor operation.
  • Once the problem is identified, use proper refrigeration practices to repair it so that your customer will be back in the ice business at maximum capacity. Or, use the information you’ve gathered to encourage that customer to upgrade the equipment.

    Moore is director of technical support for Hoshizaki America Inc., Peachtree City, GA. He can be reached at techsupport@hoshizaki.com (e-mail).

    Publication date: 03/05/2001

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