What the pounds-per-day number measures
Ice machine capacity is a harvest rate: how many pounds of ice the machine makes in 24 hours of continuous running. ENERGY STAR's commercial ice maker program covers air-cooled batch machines, which make cubes in cycles, and continuous machines, which make flake and nugget ice, with certified harvest rates from 50 to 4,000 pounds a day.
That rate changes with the room. Makers state performance at set air and water temperatures, and Scotsman's manual for its undercounter cube models shows how much they matter by giving cycle times for a mild pair, 70°F air with 50°F water, and a hard pair, 90°F air with 70°F water: its CU0715X takes 16 to 18 minutes a cycle in the mild condition and 23 to 26 in the hard one.
Size on the hot-room figure
A bar in August, a kitchen with a line of fryers, a hotel ice room with no air conditioning: these are the conditions the machine will meet on the days that matter. Sizing on the cooler figure buys a machine that looks big enough on paper and runs short exactly when the house is full.
Source: ENERGY STAR — Commercial Ice Makers — Certified air-cooled batch and continuous (flake and nugget) machines with harvest rates from 50 to 4,000 pounds a day; batch models about 10% more energy efficient and 20% more water efficient; water-cooled machines not eligible; Scotsman — Installation and User's Manual, Cube Ice Machines with Storage CU0415X, CU0715X, CU0920X — Cycle times at 70°F air/50°F water and 90°F air/70°F water (CU0715X 16–18 and 23–26 minutes); storage bin insulated but not refrigerated, so ice melts
Counting the ice you actually use
The first step in how to size an ice machine is a number of your own. Rules of thumb per seat or per room vary so much between a coffee shop, a cocktail bar and a hospital floor that they are only a starting point. A week of simple counting beats any of them.
- Count bagged ice bought on the busiest days while the old machine was short, and add it to what the machine made.
- Count how many times staff empty the bin into wells, coolers and pitchers on a peak day, and weigh one full bucket.
- Note the hours when ice runs out; that tells you the size of the rush.
- Add ice used for display, for chilling bottles and for the salad bar, which never goes back into drinks.
- Add any growth you expect: a patio season, more rooms, a longer happy hour.
Peak, not average
An average day hides the problem. A restaurant that uses 200 pounds on a Tuesday and 380 on a Saturday needs a machine and bin that cover Saturday, because that is the day a shortage costs sales. If the busy day comes only a few times a year, bagged ice for those days can be cheaper than a larger machine running half empty the rest of the time.
The machine and the bin do different jobs
The ice-making head works steadily around the clock, whether it is two in the morning or the middle of service. The bin is the reserve that absorbs the difference between that steady output and the sudden draw of a rush. A modest head on a generous bin often serves a bar better than a big head on a small bin, because the overnight hours refill the reserve.
Scotsman notes that the storage bin is insulated but not refrigerated, so some ice melts and the machine tops it up. A bin sized far beyond the day's needs means older ice at the bottom and more melt, so aim to empty it through most of its depth on a busy day.
An example worked through
Say a bar uses 300 pounds on its busiest day, and 220 of it between 5 and 11 in the evening. A machine rated at 300 pounds a day in the hot condition makes about 12.5 pounds an hour, or about 75 pounds during those six hours. The bin has to hold the other 145 pounds at 5 o'clock, plus a margin for melt, and the machine has the remaining 18 hours to refill it. Those are illustration figures; use your own counts.
Source: Scotsman — Installation and User's Manual, Cube Ice Machines with Storage CU0415X, CU0715X, CU0920X — Cycle times at 70°F air/50°F water and 90°F air/70°F water (CU0715X 16–18 and 23–26 minutes); storage bin insulated but not refrigerated, so ice melts
Matching the kind of ice machine to the job
The type of machine narrows the choice before capacity does. Each fits a different kind of room and a different way of getting ice to the glass.
- Undercounter self-contained machines make and store ice in one cabinet under a bar or a counter; good where the daily need is modest and floor space is tight.
- Modular heads sit on a separate bin or on a beverage dispenser, so the head and the storage can be sized independently.
- Nugget machines make soft, chewable ice continuously; hospitals and offices often choose them, and ENERGY STAR rates them as continuous-type machines.
- Ice and water dispensers keep the ice closed and hands out of the bin, which suits hotel floors, offices and clinics.
Source: ENERGY STAR — Commercial Ice Makers — Certified air-cooled batch and continuous (flake and nugget) machines with harvest rates from 50 to 4,000 pounds a day; batch models about 10% more energy efficient and 20% more water efficient; water-cooled machines not eligible
The water, drain and power a bigger machine asks for
More ice means more water in and more water out. Manitowoc's flake and nugget manual lists potable water use of about 45 liters per 45 kilograms of ice, which works out to roughly 12 gallons per 100 pounds. On water-cooled models the condenser uses far more, between about 276 and 522 liters for the same amount of ice in that table, roughly 70 to 140 gallons per 100 pounds, and that water goes down the drain.
ENERGY STAR notes that certified batch machines are about 10 percent more energy efficient and 20 percent more water efficient than standard models, and that water-cooled machines are not eligible for the label. A larger air-cooled machine, in turn, puts more heat into its room, so the room and the air conditioning are part of the sizing decision, along with a drain and a dedicated circuit that suit the model's plate.
Source: ENERGY STAR — Commercial Ice Makers — Certified air-cooled batch and continuous (flake and nugget) machines with harvest rates from 50 to 4,000 pounds a day; batch models about 10% more energy efficient and 20% more water efficient; water-cooled machines not eligible; Manitowoc — Flake and Nugget Ice Machines UFK, UNK, RFK, RNK: Installation, Operation and Maintenance Manual — Potable water about 45 liters per 45 kg of ice; water-cooled condenser water about 276–522 liters per 45 kg of ice
