SPECIAL REPORT: Icemakers Go Smart

Ice is nice, right? You use it to cool beverages, chill hot foods at the end of the day, display cold foods, make smoothies and frozen drinks, and chill salad bars. No matter what kind of operation you run, ice is indispensible.

You probably use ice in so many ways that one of the worst things that can happen is having the ice machine go down or not be able to meet demand during peak traffic. Fortunately, ice machines are becoming more reliable all the time, and newer models produce more ice using less water and electricity than ever before.

The last time we wrote about the category, back in 2007, ice machine manufacturers were preparing to meet new California Energy Commission regulations that established new energy and water use standards there. The standards were set by the Consortium for Energy Efficiency, a broad-based coalition of industry, government and academic experts. Working with groups like the Air-Conditioning, Heating and Refrigeration Institute, the CEE set minimum efficiency standards for a variety of equipment categories, including ice machines, which it dubbed Tier 1.

Those standards were adopted by the federal government last year and served as the initial guideline for the EPA’s Energy Star specifications, too. (Remember that CEE’s mission is to set minimum specs manufacturers must meet, and Energy Star aims to set specs for the top 20% to 25% in efficiency.) But the CEE—and Energy Star—went further. The CEE established Tier 2 and Tier 3 energy specs at the same time it established Tier 1. Tier 2 standards include water as well as energy usage, which also is what Energy Star bases its specs on.

This means you have an even wider range of efficient, Energy Star-qualified models to choose from than ever. (To find out which machines qualify, go to energystar.gov/ia/products/prod_lists/ice_machines_prod_list.pdf. To compare the efficiency of these machines in terms of both energy and water use, go to the AHRI website at ahrinet.org and click on “Search AHRI Certification Directory.”)

Still with us? The list of Energy Star-qualified machines includes only cubers at this point, though the EPA has talked for a few years now about including flakers and nugget machines. These types of machines are typically 15% more energy efficient and use up to 30% less water than cube ice machines.

Energy Star says a final draft of the proposed new specs is due at the end of this month. With a comment period after that, new specs likely will be effective sometime next year. Version 2.0 not only includes flake and nugget machines, but also revises energy and water consumption specs for cube machines.

Part of the holdup for including flakers and nugget machines was developing a test method that could compare apples to apples. What AHRI and other stakeholders have done is include ice hardness in the specs. Obviously, the harder the ice, the colder it is, and it takes more energy to get there. Flakers and nugget machines produce softer ice than cube machines, which is one reason they use less energy, and if Energy Star tried to set a single standard for all three types of machines, you’d have a lopsided playing field. But with hardness standardized in the test for both cubers and flakers, you’ll now have a clearer picture of which models are more efficient in their various categories.

Form And Function

Which brings us to your first decision when you consider a new machine for your operation: What type of ice? The two types of machines mentioned above—cubers and flakers—produce three types of ice and myriad variations on their themes.

Cubers freeze water into individual cubes. Evaporators in these machines are shaped like large ice cube trays. Water flows over the evaporator, slowly freezing until the “tray” is full. The evaporator in a flake ice machine is shaped like a barrel or tube. Water freezes on the inside of the tube, and an auger continuously scrapes the ice off the evaporator in small flakes and carries it to a collector chute. Nugget, or chewable, ice is made by compressing flake ice into pellets or nuggets.

The form you choose depends on what function you want your ice to serve. Factors to consider include presentation, hardness, heat transfer rate, displacement and customer preference. Flake ice, for example, is ideally suited for salad bars and cold food displays. A bed of flake ice not only looks good, it also chills food quickly.

The more surface area ice has, the quicker heat transfers to the ice. It also displaces more liquid volume. Nugget or chewable ice is popular in beverage service for those reasons and because many consumers like its softer, chewable consistency. A disadvantage is that it melts faster than hard cube ice, diluting beverages more quickly.

Cube ice still predominates because it can be used in many applications. Manufacturers offer models that make cubes in a range of sizes. Smaller cubes, again, offer faster cooling properties and higher displacement. Larger cubes often are used in bars and cocktail lounges because they melt slowly and offer a good appearance. And, as an option to purchasing a cuber and flaker for different applications in your stores, some manufacturers make ice crushers to complement their cube machines.

Capacity is the next decision you face. You want an ice machine that will supply you with enough ice to meet your demands at peak periods. You may use 1,000 lbs. of ice a day, for example, but use 750 lbs. between noon and 5 p.m. A general rule of thumb is to size your machine so that peak duty cycle is about 70% of the machine’s capacity. You may think that means buying more machine than you need, but typically the larger the machine, the more efficient it is.

Ice usage varies widely from one operation to another. You’ll use a lot more ice, for example, if your beverage program includes smoothies or frozen drinks than a program that doesn’t. Track your ice usage for a couple of weeks, noting peak demand periods.

Short of measuring actual usage, some general estimates for ice usage are 1½ oz. to 3 lbs. of ice per person in a full-service restaurant; 3 lbs. per seat in a bar or lounge; 30 lbs. per cubic foot for a salad bar (about 4 lbs. per sq. ft.); and as much as 5 lbs. per guest for hotel room service. In quick service, figure 5 oz. of ice per 12-oz. cup, 8 oz. per 16-oz. cup and 12 oz. per 24-oz. cup.

Most manufacturers have an ice machine sizing calculator on their websites. Simply plug in the number of customers or seats, type of ice you want to use and type of foodservice operation, and the calculators will suggest an optimal size machine.

Where The Savings Are

Flake and nugget machines make ice continuously, or until a bin sensor or timer shuts off the machine. They save energy, however, because they don’t freeze ice to the same hardness or low temperature as cube machines do. And virtually all the water introduced into the flaker is converted to ice.

Cube machines make ice in batches. In most cases, a reservoir fills with enough water to make a batch. That water is continuously circulated over the evaporator, freezing a little at a time until the “tray” is full of ice. The machine cycles into a harvest mode, and the cubes fall out of the evaporator into the bin or dispenser.

Pure water freezes more quickly than water containing any impurities, which means that minerals and other dissolved solids flow back into the reservoir and eventually must be purged. Cube machines, as a result, always use more water than what’s actually converted to ice.

Since flake and nugget machines are inherently more water and energy efficient than cube machines (and since they’re not yet Energy Star rated), we’ll focus here on what cuber manufacturers are doing to make their machines more efficient.

Basic designs haven’t changed much over the years, and each manufacturer offers its own signature characteristics, including cube shapes and machine design. One maker, for example, uses a stainless evaporator, which it claims makes colder, harder ice. Another features a horizontal evaporator; water sprays into it from below, which it says results in even fewer impurities in the cubes (and therefore colder, harder cubes).

But manufacturers have tweaked their machines in myriad ways to make them more efficient and cost-effective. Here are a few:

If you can’t stand the heat, take it out of the kitchen. Manufacturers are offering more modular models than ever, putting the compressor and condenser on the roof. That takes heat and noise out of the facility, allows the components to operate more efficiently, and lets you put the ice-making head right on top of a beverage dispenser or ice bin.

One manufacturer says its oversize condenser provides better heat transfer and eliminates the need for an air filter, ultimately letting the machine run cooler. And it has several self-contained models that discharge air from the top of the machine instead of the sides, letting you squeeze the machine into a narrower spot.

Make more with less. Speaking of narrower, several manufacturers have designed taller, narrower machines that produce as much or more ice in a smaller footprint. Some of this is due to remotely locating the compressor and condenser, leaving only the evaporator inside. But several self-contained units also have slimmed down, producing as much ice in a 30” profile as an old 36” machine would.

Use more efficient components. In the past several years since California upped its efficiency specs, manufacturers have updated machines with better parts. Compressors, fan motors and pumps now are far more efficient than they were five years ago. Manufacturers also are using fans with new blade designs that are both more efficient and quieter than in years past. And more of these components are common to a wider range of models, making service easier and less costly.

Size it up. Just as refrigeration manufacturers have tweaked their systems to better match compressors to evaporators, ice machine makers have done a better job of sizing, too, including sizing valves and refrigerant lines to make them operate more efficiently.

In some cases, they’ve oversized components for greater efficiency, too, such as the oversized condenser noted above. Another manufacturer purposely builds machines with larger evaporators, suggesting that a machine with a longer freeze cycle and fewer cycles puts less strain on the compressor and use less energy overall.

Bring on extra help at harvest time. Most machines used to reverse the freezing process, injecting hot refrigerant gas into the evaporator to loosen the cubes enough to fall out. With the introduction of remote units, however, manufacturers have been able to route cooler refrigerant vapor from the refrigerant accumulator tank into the evaporator to loosen ice.

To further minimize this “defrost” cycle and save additional energy, makers have added their own harvest assist techniques. One uses a patented pressure transducer to help harvest ice. Another uses a small air compressor to break the suction between the ice and the evaporator plate. Yet a third uses a mechanical pin to push the ice slab away from the plate.

In Control

New digital technology has really taken off, improving ice machine performance in two areas–efficiency and reliability.

Programmable models let you determine the best times to produce ice for your operation. If your peak demand days are on weekends, for example, you can program your machine to produce continuously on those days and less on others. Digital control over production cycles also lets you shift demand load on your electric bill. Since many utilities give you a price break if you shift electric usage to nighttime hours, you can program your machine to make enough ice at night to get you through the next day and save money doing it.

The folks at Pacific Gas & Electric Co.’s Food Service Technology Center conducted a field study of several ice machines and concluded that in many cases the potential savings of demand load shifting are tremendous. FSTC’s Don Fisher plans to present recent findings on ice machines and potential energy and water savings at our Multiunit Foodservice Equipment  Symposium, MUFES ’12, scheduled for Jan. 28-30, 2012, in Austin, Texas.

Even if you don’t spring for a digital machine (though they’re not much more expensive, and payback can be quick), some manufacturers offer a bin sensor as an option. The sensor monitors the level of ice in the bin and turns off the ice machine when there’s enough on hand.

Some digital models also have a sensor that measures total dissolved solids in the water in the machine’s reservoir. When water quality is poor, more is used to purge the residue at the end of a cycle. Conversely, less is used when the sensor determines a lower level of TDS.

Digital models also improve reliability by anticipating maintenance and service issues so you can address them before they become problems. A couple of manufacturers offer models with diagnostic boards that monitor ice machine performance. Indicator lights and on-screen messages alert you when it’s time to change air or water filters and clean or delime the machine.

If the machine does need service, the diagnostics board can lead a service tech through the troubleshooting regimen to get at the problem quickly. Digital memory also lets a service tech see the machine’s performance over time. Some models allow you to monitor this data remotely so you can keep track of how machines are performing and quickly address those that aren’t producing up to expectations.

Keeping It Clean

Cleanliness also can dramatically affect performance as well as customer safety. Almost all manufacturers now also use antimicrobial materials for some parts in their machines. There are several proprietary types, but they all essentially work in the same way. Plastic parts are impregnated with the antimicrobial substance, which helps retard the growth of mold and slime.

Some models go a step further and offer an automatic cleaning cycle. At selected intervals, such as two, four or 12 weeks, the cleaning cycle washes out the machine with an acidic solution to remove dirt and lime scale. The cycle runs sanitizing solution through the machine, rinses it thoroughly and puts the machine back into service, ready for the next ice-making cycle. The cleaning cycle can be operated manually, too.

To prevent cross-contamination, most models let you put the ice-making head right on top of an ice bin or ice dispenser. One nugget ice machine maker offers a pump that lets you fill bins or dispensers from as far away as 75’, keeping the noise of the icemaker far away from beverage dispensers in a dining area, for example. The company now also makes a smart diverter valve that lets you deliver ice from one ice machine to two locations.

If your current ice machines seem to be working overtime to keep up with demand, now may be a good time to consider retiring them and investing in new, more energy- and water-efficient machines.