Section 3

Ice Machine Operation

 

Section 3

 

Ice Machine Operation

Sequence of Operation

 

Ice Making

 

Control Board Relays

 

 

 

1

2

 

3

Length of

 

Sequence of

Compressor

Hot Gas Valve

 

Water Pump

 

 

“ON” Time

 

Operation

Water Fill Valve

 

Fan Motor

 

 

 

 

Start-Up1

Off

On

 

Off

2.9 Minutes

1.

Water Purge

 

(175 Seconds)

 

 

 

 

2.

Refrigeration

On

On

 

Off

5 Seconds

 

System Start-Up

 

 

 

 

 

 

 

3.

Freeze Cycle

On

Off

 

On

Automatically

 

determined

 

 

 

 

 

 

4.

Harvest Cycle

On

On

 

Off

Automatically

 

determined

 

 

 

 

 

 

5.

Auto Shut-Off

Off

Off

 

Off

Until bin thermostat

 

re-closes

 

 

 

 

 

 

1Initial Start-Up or Start-Up After Automatic Shut-Off

INITIAL START-UP OR START-UP AFTER AUTOMATIC SHUT-OFF

1. Water Purge

The water fill valve and the hot gas valve are energized for 2.9 minutes (175 seconds). This ensures that the ice making cycle starts with fresh water, and that the refrigerant pressures are equalized prior to refrigeration system start-up.

2. Refrigeration System Start-Up

The compressor starts 2.9 minutes (175 seconds) after the water fill valve and hot gas valve are energized. (The water fill valve and hot gas valve remain energized for 5 seconds during compressor start-up, and then shut off.) The compressor remains on throughout the entire freeze and harvest cycles.

3. FREEZE CYCLE

The condenser fan motor and water pump are energized and remain on throughout the entire freeze cycle. An even flow of water is directed across the evaporator and into each cube cell, where it freezes.

The control system automatically determines the length of the freeze cycle by monitoring the temperature of the refrigeration system liquid line.

4. HARVEST CYCLE

The condenser fan motor and water pump de- energize. The water fill valve energizes to purge the water in the water trough. The hot gas valve also energizes at the beginning of the harvest cycle to divert hot refrigerant gas into the evaporator. The hot refrigerant gas warms the evaporator, causing the cubes to slide, as a sheet, off the evaporator and into the ice storage bin.

The control system automatically determines the length of the harvest cycle, based on the temperature of the refrigeration system liquid line at the end of the freeze cycle. At the end of the harvest cycle, the ice machine returns to another freeze cycle (step 3, above).

5. AUTOMATIC SHUT-OFF

The ice machine shut-off is controlled by the level of ice in the ice storage bin. When the bin is full, ice cubes contact the bin thermostat bulb holder, which cools down and opens to stop the ice machine. The ice machine remains off until enough ice has been removed from the bin. This causes the thermostat bulb holder to warm and close, restarting the ice machine. When the ice machine restarts, it returns to the start-up sequence (steps 1 and 2, above).

3-1

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Manitowoc Ice QM20 service manual Section Ice Machine Operation, Sequence of Operation
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QM20 specifications

The Manitowoc Ice QM20 is a top-tier commercial ice machine renowned for its robust performance and innovative features. Aimed primarily at the food service and hospitality industries, this ice maker excels in producing high-quality ice efficiently, delivering reliability and convenience in one compact unit.

One of the standout features of the QM20 is its ice production capacity. It can produce up to 2,030 pounds of ice per day, making it ideal for high-demand environments like restaurants, bars, and hotels. The machine generates chewable, nugget-style ice, which is not only popular among consumers but also highly effective for chilling beverages quickly. The texture of the ice helps to enhance the user experience, making drinks colder faster while maintaining their flavor profile.

The QM20 is equipped with advanced technologies that simplify operation and maintenance. The machine includes a user-friendly digital interface that provides real-time information about ice production and maintenance alerts. This feature ensures that users can easily manage operations, reducing the risk of unexpected outages. One of its notable characteristics is the self-diagnostic feature, which can identify potential issues before they escalate, ensuring optimal performance and longevity of the unit.

Energy efficiency is a key consideration in the design of the QM20. It is engineered to operate optimally while using minimal energy, making it an environmentally friendly choice for businesses conscious of their carbon footprint. In addition, it features a built-in water filter that helps to improve ice quality and taste, while also prolonging the lifespan of the ice machine by reducing mineral buildup.

Durability is another highlight of the Manitowoc Ice QM20. Constructed from high-grade stainless steel, this unit is designed to withstand the rigors of daily use in busy commercial environments. The easy-to-clean design further promotes hygiene, an essential factor in the food service industry.

In summary, the Manitowoc Ice QM20 is a robust, efficient, and technologically advanced ice machine that meets the demands of the commercial sector. With its high production capacity, innovative features, and durable construction, it stands out as a leading choice for establishments looking to enhance their ice-making capabilities while providing exceptional service to their customers.
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