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HVACR318 –Refrigeration II

Commercial Ice Machines

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Packaged Ice Equipment

• Packaged commercial ice machines are the ones you find in restaurants and hotels.

• Packaged ice machines are a single unit.

• There are other machine types used in residential or block ice houses – we will not be discussing those here.

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Four Step Cycle, Flush

• Most machines have a 4 step cycle: Flush, Fill, Freeze, Harvest.– Flush Cycle:• Flushes the water from the reservoir and

replaces it with fresh water from the tap.• This provides basic cleaning and removes

minerals that are left over from the freeze cycle.• This is usually the first cycle when you turn

the machine on.

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Four Step Cycle, Fill

− Fill cycle• Also occurs during the flush cycle and brings

the water level to the right place for the next freeze cycle.

• Ends via time or float switch.

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−Freeze Cycle:• This is the cooling cycle – This is when the

compressor is running, creating a cold evaporator coil and creating ice.

• The pump also circulates the water during the freeze cycle.

• The freeze cycle is terminated by time or ice thickness.

Four Step Cycle, Freeze

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Four Step Cycle, Harvest

− Harvest Cycle:• Compressor goes into hot gas defrost and

breaks the ice loose from evaporator coil.• Ice is then flushed off of coil by the water

circulating and strained out into the bin.• Water continues to circulate.• This cycle is terminated by temp, pressure or

time.

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Cycle – Additional Notes

• Once the harvest cycle ends the sequence starts all over.

• VERY IMPORTANT:– Ice machines do not have a defrost cycle,

it is a harvest cycle.– Ice machines do not have a cooling cycle,

it is a freeze cycle.

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Components

• Most components of ice machines are similar to that of basic commercial refrigeration units.−The compressor and the condenser are

the same.−The hot gas solenoid and the TXV are the

same.

• What is different are some of the components, the evaporator, and the sequence of operation.

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Components

• Bin Control: A mechanical or solid state sensor that senses the level of the ice in the bin.– Sometimes uses a pressure sensitive arm.– Sometimes uses an infra-red beam.– Sometimes uses a thermostat that senses

the ice level.–Main purpose is to stop production when

bin is full.

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Components

• Water Solenoid:– Allows fresh water to enter the system

when the sequence calls for it. This is a solenoid valve on the fill line.

• Drain / Waste Solenoid:– Allows water to drain out of the system

during the purge or waste cycle.

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Components

• Circulating Pump– Circulates water across the evaporator to

make the ice.– Circulates water across ice during harvest

cycle.– Pumps the water out in the waste cycle.

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Components

• Float:– Senses water level in the reservoir.–Will shut the machine down in a low water

situation.–Will shut off fill sequence and signal for

start of freeze cycle.– Sometimes senses the time to begin the

harvest cycle.

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Components

• Spray Bar– Takes water from the pump and

distributes it across the evaporator for even water flow.

• Thickness Sensor– Senses the ice thickness on the

evaporator coil. Signals for start of harvest cycle.

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Components

• Control board or panel– The board or panel is a mechanical or

solid state part that controls the entire operation of the machine.

– This panel is not repairable; if it’s bad it must be replaced.

– Controls on ice machines are either DC or line voltage. Make sure you know what you are working with.

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Evaporator

• Evaporator− The evaporator is either a solid or a

formed plate for ice to form on.− Water runs across the plate and freezes

in the forms.− A thickness sensor senses when ice is

thick enough to harvest.

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Evaporator

− The evaporator is kept between 10°F and 20°F.

− The incoming water temperature determines the productivity of the ice machine.

− The evaporator is coated with a nickel plating. Do not use harsh chemicals to clean it.

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Evaporator

− Evaporators can be mounted at an angle or vertically in the machine.

− Vertically mounted evaporators allow greater capacity.

− It is very likely that you will have more than a single vertical evaporator in a machine.

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Electrical Sequence

• Bin-Full / Shut Off – Consult the Manitowoc G400 Handout,

Page 25, for a detailed description of the sequence. Main points are:• Bin switch is OPEN.• All other components are OFF.

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Electrical Sequence

• Freeze Cycle − Consult the Manitowoc G400 Handout,

Page 26, for a detailed description of the cycle. Main points are:• Unit is making ice• Toggle switch is in Freeze or Ice position.• Bin switch is closed.• High pressure is closed• Liquid line (pump down) is open and

energized.• Low pressure cut-out is energized

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Electrical Sequence

− Main Points, Freeze Cycle, cont’d:• Compressor relay is closed• Compressor is on• Remote fan motor is on (condenser fan)• Harvest pressure is closed• Primary transformer is energized• Ice sensor relay is open.• Water pump is turned off at first, then turned

on after a pre-chill (page 28 of the handout).

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Electrical Sequence

• Harvest Cycle – Consult the Manitowoc Handout, Page 30, for a

detailed description of the sequence. Main points are:• Bin switch is closed• Hot gas solenoid is open and energized.• Dump solenoid is open• Harvest cycle ends when harvest pressure

opens or time expires.

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Cleaning an Ice Machine, Overview• Per health department guidelines, ice

makers must be cleaned at least four times per year.

• Remember, ice is a food. Your goal is to have the machine produce clean, uncontaminated ice that people can consume safely.

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Cleaning, Step 1

• Make sure the customer has taken as much ice out of the ice machine as they will need until the machine recovers.

• Then dump all remaining ice in the bin. Completely empty the unit.

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Cleaning, Step 2

• Follow the manufacturer’s directions for washing the unit. This procedure normally requires a couple ounces of nickel-safe cleaner and the wash/rinse cycle on the controls.

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Cleaning, Step 3

• Rinse the unit thoroughly, per manufacturer’s directions.

• Some people are extremely allergic to chemicals, so you cannot leave any trace of soap or chemicals behind that might be mixed into the ice.

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Cleaning, Step 4

• Disassemble the entire unit. Consult the manufacturer’s instructions for proper disassembly.

• During disassembly, take great care to keep track of all loose, small parts (screws, etc.) that can easily be lost in a commercial setting.

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Cleaning, Step 5

• Wash and rinse all parts.• Sanitize (bleach and water works well)

all portions of the machine and bin that come into contact with ice.

• Rinse with clean water.• Never use dirty rags during the

cleanup.

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Cleaning, Step 6

• Reassemble the machine. the reassembly procedure is usually a direct reversal of the disassembly procedure.

• If reassembly is done correctly, there will be no left over parts.

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Cleaning, Step 7

• Test the machine.• You must stay on site for a minimum

of two cycles. If you make any adjustments, you must stay for another cycle after the adjustment.

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Cleaning, Step 8

• Wipe down the outside of the machine and make it look clean.

• Remember: Appearance is the first thing that people notice in a restaurant, or any place that deals with food. The shinier, the better.

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Things to Watch For During Service Visit:• Clogged water filter: will reduce the

thickness of the ice.• High incoming water temperature; this

will increase the freeze time and sometimes reduce thickness of ice.

• If machine has a thickness sensor, make sure it does not move.