How to Get
Maximum Ice
Machine Production
Air and water temperatures lead
a list of conditions to check when
servicing ice machines
BY DANNY MOORE
W
ithout a doubt, the most common customer
complaint that a service tech receives concerning ice machines is low production. This is the
time of year for spring cleaning and the ice
machine is a good place to start. Preventive maintenance
is the key to getting maximum production from an ice
maker.
H e re are some basic conditions you need to know
about and check when perf o rming preventive maintenance on ice machines:
• The effects of temperature: It is important to
remember that temperature effects refrigeration eff i c i e ncy, especially in an ice machine. In the winter season,
water and ambient temperatures are cooler. This results
in shorter freezing times and better efficiency of the
refrigeration system.
Ice machines will operate at maximum efficiency at
70° F air and 50° F water temperatures. As outside temperatures rise, so do the water temperature and the ambient around the ice machine.
• Water temperatures: It is not uncommon to find
water temperatures in excess of 90° F feeding an ice
machine in mid summer in the Deep South. Temperatures
a round 100° F often occur in Texas and Arizona during
the summer – and that’s the cold water temperature.
Incoming water temperatures can be affected by the
routing of the water supply line. If you find higher water
temperatures, make sure that there is not excessive water
supply line coiled behind the unit and being warmed by
the condenser exhaust.
It is important to note that in warm climates, a customer can pick up additional production by prechilling
the incoming water. Prechilling can be expensive in some
cases and the customer should weigh the cost benefit of
getting the equipment necessary to do this function.
Tip: You can get inexpensive prechilled water by ro u ting the water supply line through a walk in cooler and
adding a few loops inside to allow additional cooling
capacity of the supply water.
• Air temperature s : Ambient air temperatures rise
accordingly with the spring and summer seasons. The
customer can expect some drop in production as the
summer approaches. How much? Manufacturers generally provide perf o rmance data charts that show appro x imate production at varying water and ambient temperature ranges.
The chart on the next page shows a basic 500-pound
cuber machine at diff e rent air and water temperatures.
Notice the difference in ice production between perfect
air and water temperature conditions of 70° F/50° F and
summer conditions of 90° F/70° F temperatures. Many
manufacturers provide this type of data in a technician’s
pocket guide format or in model specific service manuals.
Excessive ambient temperatures can be the result of
improper location. While it is great for the chef to have
ice close by when kitchen temperatures sore, it is not a
good idea to install the ice machine beside the oven or
steamer. These appliances generate excessive heat and
can impact ice production.
Likewise, placing the ice machine in a back storage
room or closet without proper air circulation will reduce
the efficiency and production. The perfect location will
have adequate airflow, decent year- round temperatures,
and room to perf o rm service and preventive maintenance.
The effects of scale
As ice forms on the evaporator-freezing surface, pure
water freezes first, which causes the minerals in the water
Ambient temp
(° F/° C)
70/21
80/27
90/32
100/38
Water temperature (°F/°C)
50/10
499*
475
468
461
226**
216
212
209
70/21
468*
427
393
353
212**
194
178
160
90/32
428* 194**
389 176
384 174
317 144
Approximate ice production per 24 hours in pounds/
kilograms per day. (Pounds* Kilograms**)
to separate (wash out) and continue to circulate through
the water system. These minerals can attach to any surface they come in contact with and tend to build a film of
scale on these surfaces.
As the scale grows, it insulates the freezing surface and
impedes heat transfer. Scale is more visible when the surfaces are dry; the color will vary due to the type of minerals in the local water supply.
As an example, lime or calcium scale will be off-white
in color, while iron scale will turn a rusty red color. Algae
or slime growth may also occur in some locations. This is
due to air or water-borne bacteria that can settle in the
wet areas and grow.
A scaled evaporator will be inefficient in forming ice
during the freeze cycle and releasing the ice during the
harvest cycle. This will cause low production and can also
cause ice to stick on the evaporator and re f reeze. As the
ice refreezes, it develops into a freeze-up and no usable
ice is produced.
A scaled evaporator is the major cause for a freeze-up
condition. This is true for any piece of ice making equipment. Scale must be removed to regain production efficiency and ice release.
The maintenance solution
A thorough preventative maintenance inspection and
cleaning will improve efficiency and provide maximum
production. Once the unit is cleaned, it should be sanitized to reduce bacterial growth in the cold damp evaporator compartment and ice-drop zone.
Generally, manufacturers recommend a preventive
maintenance schedule that includes cleaning the water
system with an acid-based ice machine cleaner, sanitizing
the system to eliminate bacteria along with other component checks. Clean and sanitize the storage bin as part of
your preventive maintenance program.
T h o roughly flush the water system and bin before putting the unit back into operation. This will assure your
customer of clean fresh ice. Additional preventive maintenance may be re q u i red in areas with poor water quality.
Cleaning instructions are usually located on a 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 manufacture r, as this will
Manufacturers recommend a preventive maintenance schedule that includes cleaning the water system with an acidbased ice machine cleaner.
protect a plated-type evaporator from damage due to
harsh chemicals.
Once you have inspected the unit and cleaned and sanitized it as necessary, determine if there is a production
problem. This will re q u i re you to time a complete cycle
from the beginning of one freeze cycle to the beginning of
the next freeze cycle. You will also need to catch the ice
produced during this cycle and weigh it.
The formula for checking ice production is simple.
Divide 1,440 by the cycle time in minutes 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 hours. Production formula:
1,440 divided by cycle time multiplied by the ice dro p
weight equals production per day.
Once the production test is completed, compare it with
the manufacture r’s data. If it’s close – that is, within +/-10
percent – you likely have maximum production.
At this time you will want to discuss with your customer the approximate amount of ice he needs. Make a
list of what the ice is used for and the approximate
amount needed. Add a 25 percent fudge factor and compare the needs to the present supply. If the production is
inadequate, seize the opportunity and sell a new machine.
It is possible, however, that the customer may have the
appropriate machine production and not enough storage
to get them through hot days. In this case, there are usually two choices. They can bank ice in bags in their fre e zer for those days or change to a larger storage bin.
A final word
While water temperatures and ambient conditions along
with scale buildup account for most low-production calls,
t h e re are other problems that can occur. An ice machine
always should be clean and operating within the manufacturer’s specifications of air and water temperatures before
you move on to diagnose other causes.
If the production is not close to manufacturer specifications even after the preventive maintenance, it’s time for
additional diagnosis to determine the cause of the low
production. Potential causes include an improper or contaminated refrigerant charge and other component failu res. Refer to the manufacturers service manuals or technicians’ pocket guides for instructions on how to diagnose
these system failures.
Once the problem is identified, use proper refrigeration
practices and service techniques to repair it so that your
customer will be back in the ice business at maximum
capacity.◆
Danny Moore is director of technical support for Hoshizaki
America Inc., which manufactures commercial ice
machines and reach-in products. For more information, call
800-233-1940 ext. 382.
If the production is not close to manufacturer specifications
even after the preventive maintenance, it’s time for additional diagnosis to determine the cause of the low production.
Ice machine maintenance checklist
To ensure proper operation of your customers’ ice machines, make sure you check:
✓ The water distribution system for restrictions and consistent water flow.
✓ The evaporator for scale buildup and clean as necessary.
✓ For talc or mineral buildup in reservoir. Remove and flush thoroughly.
✓ The pump motor operation (broken impeller, slow pumping or leaking).
✓ The water flow through the external water filter. (Low water flow to unit.)
✓ The strainer, inlet water valve screen for obstruction or scale.
✓ The float switch (if used) for scale, which causes sticking.
✓ The float valve assembly adjustment and operation (if used).
✓ The air filter, condenser fan blade and coil for dust, grease and grime.
✓ For proper drainage or water backup in the bin that can melt ice away.
✓ For water overflow of the reservoir that washes ice away.
✓ The bin control for proper location and operation.
For ice flaker machines (gear driven auger machines), make sure you:
✓ Inspect auger and mechanical seals.
✓ Check auger bearings for wear.