More than 2.5 million ice makers are operated in restaurants, hospitals, hotels, and other commercial facilities in the United States. Together they consume more than 13.5 billion kilowatt-hours (kWh) of electricity each year and accumulate more than $1.62 billion in annual electricity bills. The energy efficiency of new ice makers has improved considerably between 1994 and 2012, with an average machine increasing in efficiency between 16 and 32 percent; a new ice maker will last for 7 to 10 years. There are now many efficient models to choose from, some of which provide substantial energy savings with little or no incremental cost over less-efficient models—a win-win situation. With new state and federal standards coming into effect, the number and diversity of energy-efficient ice makers will continue to increase.
What are the options?
Ice machines produce various kinds of ice for a range of applications. The types of ice produced are cube, flake, crushed, and nugget.
- Cube ice is clear and comes in several shapes—rectangular, crescent, pillow-shaped, pure cube, or other regular shapes. The largest dimension is about 1.25 inches (3.18 centimeters). Pieces of cube ice range in weight from 0.16 to 0.50 ounces (4.8 to 14.0 grams) and contain minimal amounts of liquid water. More than 80 percent of ice machines sold in the US make cube ice.
- Flake ice comes in chips or flakes that contain up to 20 percent liquid water. Flake ice tends to conform to the surface of items that rest on it and is typically used in supermarket display cases, on fishing boats, or anywhere food needs to be preserved for short periods. Flake ice may also occasionally be used in soft drinks.
- Crushed ice consists of small, irregular pieces made by crushing larger chunks of ice. Its primary use is for keeping drinks cool.
- Ice nuggets, made by extruding and freezing slushy flake ice into small pieces, are also used primarily to cool drinks.
For more about types of ice and the machines that make them, see Chapter 43 of ASHRAE’s 2014 ASHRAE Handbook.
Types of machines Ice machines can be mounted above a storage bin or integrated with an attached insulated bin, a style known as a self-contained unit (Figure 1). Integrated units are the simplest to install but usually come with a fixed capacity. The capacity of nonintegrated units can be increased by stacking additional ice makers on top of the first machine or by placing two machines side by side on top of a larger bin.
Ice makers are also classified as batch or continuous in operation. Batch models tend to produce ice that is purer than its source water because the freezing process removes impurities. In continuous units, chemicals tend to remix in an ice/water combination. Controls for batch ice makers are more complicated: They must end the freezing process at the proper time to start a thawing cycle and resume the freezing process after the ice has been harvested.
Condenser types. Ice makers are available with three different types of condensers:
- Air-cooled ice makers generally use the most energy but are less expensive than water-cooled models. They also use less water.
- Water-cooled models tend to be more efficient than air-cooled units. There is no addition to air-conditioning loads because the heat removed in making the ice is discharged outside the building.
- Remote air-cooled condensers transfer the heat generated by the ice-making process outside of the building. Like water-cooled units, they reject heat outside of conditioned spaces and therefore do not increase air-conditioning loads. They also reduce noise levels inside by up to 75 percent, but there are extra installation costs for running lines to a remote location. Remote condensers can use remote compressors for further efficiency gains.
Bin types Ice-storage bins are available in a range of sizes, usually with a full-width door that allows users access to the ice. Bins are usually sized to hold 10 to 12 hours’ worth of ice production. Larger bins are available for applications in which ice is only changed once or twice a week, such as supermarket displays. Sealed, sanitary units are also available, but they’re much more expensive than standard units. They are often used in hospitals, motels, and restaurants, and for any operations in which ice comes in direct contact with food or drink.
Water heat recuperation Some ice makers direct the incoming water behind the evaporator plate or over the ice to use the heat of the incoming water to assist in the ice-harvesting process. This step also serves to prechill the incoming water and cuts energy use significantly.
Water treatment system Ice makers can be run directly from tap-water supplies, but some applications may require additional water treatment. In general, if the total chemical content of the incoming water is greater than 400 parts per million, auxiliary water treatment is recommended.
Self-cleaning systems A relatively new option among ice makers is the self-cleaning machine. Typically, ice makers are cleaned and sanitized every two to six weeks, which requires emptying the bin of ice, adding cleaning solution, switching the controls to a cleaning mode that circulates the cleaning solution through the machine, and then producing enough ice to be sure the machine is cleared of the solution. Self-cleaning models automate most of these steps.
Energy-efficient units In 2013 Energy Star updated its specification requirements for ice machines. These initial levels cover only air-cooled ice makers and those that make cube (not flake or nugget) ice. The Energy Star program has stated its intention to include flake and nugget machines once a test standard is available and adequate data are collected for deriving performance requirements. Energy Star hosts a Commercial Food Service (CFS) incentive program with local utilities, which offer rebates for energy-efficient machines. Rebates typically range from $100 to $500. For more information, see the Energy Star CFS website.
The Consortium for Energy Efficiency (CEE) has also created voluntary standards for commercial ice maker energy and water efficiency updated in 2015. The CEE standards, along with a list of ice makers that meet the standards, are presented on the webpage CEE High Efficiency Specifications for Commercial Ice Machines. Both Energy Star and CEE specifications are great certification schemes to follow when shopping for ice makers. Table 1 compares levels of energy consumption for a sample machine that makes 800 pounds of ice per day at current and planned federal efficiency standards, along with those required by Energy Star and the CEE. To get the maximum cost-effectiveness and greatest payback, CEE Tier 1 or Energy Star labels are typically the best bets, and CEE Tier 2 units may offer increased savings at additional cost.
In some cases, high-efficiency ice makers have little or no incremental cost versus less-efficient models, yielding very short (or even immediate) simple payback periods. In other situations, simple payback periods may be as long as 10 years or more, making the equipment less cost-effective (Table 2). It’s important to pay close attention to both expected energy savings and incremental costs when purchasing a new machine to ensure that you’re getting the most cost-effective option.
How to make the best choice
Determine required capacity Manufacturers provide sizing guidelines to help users pick the most economical combination of ice maker and storage bin. The guidelines are based on the type and size of the application. For example, an ice maker for soft drinks in a fast food restaurant might be expected to be in service seven days a week at its average level of ice production and might have to produce ice at a peak rate of 150 percent of average for two of those days. Having some extra capacity is a good idea for these peak times. A rule of thumb is to size a machine to provide 0.25 to 0.5 pounds (0.11 to 0.23 kilograms) per customer, though check with the manufacturer based on your facility’s needs.
Oversizing an ice maker can increase energy consumption due to excessive standby losses On the other hand, larger ice makers generally are more efficient (they consume less energy per unit of ice) than smaller ones. It’s important to pick a unit that most closely matches your quantity requirements. Ice machines are designated by the amount of ice that they can produce in a 24-hour period, under reference conditions of 70° Fahrenheit (F) ambient temperature and 50°F inlet water temperature. Typical sizes are 250, 400, 500, 650, 800, 1,000, 1,200, and 1,400 pounds per 24 hours, but some machines can make several tons of ice per day. Actual capacity varies with both ambient temperature and water temperature. Manufacturers usually recommend using the capacity listed at the test conditions used by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI): 90°F ambient air and 70°F water. Selecting equipment based on the capacity at those conditions will ensure that adequate ice can be produced under most conditions encountered during operation.
Pick a unit with an appropriate noise level The noise level of ice makers is typically equal to that of a window air conditioner, which is acceptable for most applications. In some cases, lower levels may be desirable, and the buyer should ensure that the manufacturer can provide equipment that meets those requirements.
Pick a reliable unit Most purchasers of ice-making machines choose them as much for reliability as for efficiency or first cost. Although reliability data for specific equipment are not available, you can make a sound choice by looking for equipment with the fewest moving parts and with controls that include diagnostic capabilities. In addition, two small machines rather than one large ice maker can provide more reliable service if one breaks down.
Look for an easy-to-maintain model Even the most reliable ice makers require a fair amount of maintenance if they are to last more than a few years. Regular cleaning and sanitation treatments are necessary for both the ice-storage and ice-making parts. The best bet is to go with equipment that includes clear, simple installation and maintenance instructions and procedures.
Consider water costs in areas where water is expensive One hundred pounds of ice is equal to about 12 gallons (45 liters) of water. The amount of water used to make that much ice varies widely, in the range of 13 to 35 gallons (49 to 132 liters). The extra water is used for melting and releasing the ice and for keeping the equipment operating smoothly and cleanly. Where water prices are average, water costs for making ice are less than 30 percent of the electricity cost. But in areas where water is expensive, water use may be an important consideration.
There is also a connection between water use and maintenance costs. Some self-cleaning machines use three times as much water as standard models, but they save on labor costs. Higher water consumption also reportedly improves overall machine reliability by keeping components such as the water pump free of scale and by keeping the evaporator clean. If water costs are high in your area, ask equipment manufacturers about water-conserving options.
Make ice overnight Electricity can be charged based on consumption, but also based on demand, which is the peak amount of power customers draw in a given month. By switching nonessential equipment to run at times when demand on the grid is low, energy customers can save by taking advantage of off-peak periods. This can be done through timer controls. Researchers from Pacific Gas and Electric Co. and Fisher-Nickel Inc. published a paper on ice machine efficiency in 2012 for the American Council for an Energy Efficient Economy (ACEEE) Summer Study on Energy Efficiency in Buildings titled Commercial Ice Machines: The Potential for Energy Efficiency and Demand Response (PDF). The study found a massive savings potential for switching machines to off-peak use. For a machine with 1,130 pounds of capacity, the study calculated that by using a simple time clock to shift ice production to off-peak periods, annual savings would amount to $1,194 or 38 percent of total electricity cost.
Making ice in off-peak periods is possible because of the storage bin. Larger-capacity machines are inherently more efficient. If a facility uses this off-peak approach, it’s recommended that the ice maker can operate with an average duty cycle of 75 percent to balance size and cost with the amount of reserve ice needed for high-demand days.
What’s on the horizon?
New US federal and state standards will continue to push ice-maker efficiency upward. Federal energy-efficiency requirements taking effect in 2018 will be similar to the current (voluntary) CEE Tier 1 standards. The federal standards will also include water-efficiency requirements.
From a technological standpoint, ice makers are now being designed with the ability to shut off automatically at specified times without external time controls. This allows them to take advantage of off-peak energy consumption—for example, making ice at night and shutting off during the day—which can help save money in cases where peak demand charges are a significant portion of your company’s energy bill. As an added benefit of running ice makers during off hours, noise is reduced during daytime business. Incremental gains in ice-maker energy efficiency continue to be made as well, mostly from improvements to compressors, which consume more than 90 percent of the energy an ice maker uses.
Who are the manufacturers?
The leading manufacturers of ice-making machinery are:
- Fujian Snowman Co. Ltd.
- Hoshizaki America Inc.
- Manitowoc FSG Operations LLC
- Scotsman Ice Systems
AHRI publishes a directory, Automatic Commercial Ice-Cube Machines and Ice Storage Bins, that presents more manufacturer and product information.
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