Ice Machines Introduction
Ice makers use more water than just the water contained in the ice. This equipment can often be very inefficient in water use. The typical icemaker uses 2 or 3 times more water than needed to make the ice we consume. These water using machines can be found everywhere; hospitals account for 39.4 percent of all commercial ice-maker purchases, followed by hotels (22.3 percent), restaurants (13.8 percent), retail outlets (8.5 percent), schools (8.5 percent), offices (4.3 percent) and grocery stores (3.2 percent).
There are two basic equipment designs: air-cooled refrigeration units and water cooled refrigeration units. The air-cooled units are usually more water efficient; while the water cooled units are usually more energy efficient. Both types vary greatly in water efficiency, even within its own design type. The water efficiency is measured by the industry in “gallons of water per 100 lbs (45.36 kg) of ice”. Perfect water efficiency would equate to 11.97 gallons (45.3 L) of water to produce 100 lbs (45.36 kg) of ice. Most ice makers’ water use ranges between 18 to 200 gallons (68 L to 756.9 L) of water per 100 lbs (45.36 kg) of ice. This represents a water efficiency range of 66% to only 5%. Thus, 34% to 95% of the water used is dumped down the drain. The water varies for several reasons.
As the ice is formed in the freezing trays, minerals in the water collect in the equipment. These minerals must be occasionally rinsed off the freezing trays and the water reservoirs. Ice makers have a variable setting to initiate a rinse cycle at desired frequencies. The frequency of rinse is to be determined by local water quality and site requirements. Some new model actuate the rinse cycles based on sensor readings of minerals. Often the ice maker is set to rinse more often than necessary, resulting in water waste.
The “quality” of the ice can also affect water use. Some ice makers are designed to produce clearer and smoother ice by using a repeated freezing and partial thawing cycle while the ice is produced. This results in ice cubes that are smoother, without air bubbles and more crystalline like. Unfortunately, this aesthetic quality wastes a lot of water and serves no useful purpose; frosty ice cools just as well as clear ice.
Water cooled ice makers are often the most inefficient in water use, although sometimes providing significant energy savings at the point of use. It is important to note that there are many air-cooled ice machines more energy efficient than some water-cooled ice machines. Water cooled machines generally use potable water to remove heat from the refrigeration equipment. In years past, most of these machines used single-pass cooling – dumping the water into the sewer as it exited the machine. Fortunately, many manufacturers are started to abandon this wasteful design. Some newer designs re-circulate the water after it passes through a cooling tower or heat exchanger, but these still require large amounts of make up water. While air-cooled machines generally have a water efficiency of 40% to 66%, water cooled machines are usually less than 15% water efficient.
The water efficiency of most makes and models can be obtained by downloading “Certified Automatic Commercial Ice Makers Directory from the Air-conditioning and Refrigeration Institute at www.aridirectory.org.
thomas pape