I’ll admit it, I am an ice snob. I really like those little flat square ice cubes that most bars seem to serve. They are small enough that it is easy to crunch them, and they are always crystal clear.
In my years of dealing with ice machines, I have learned one or two things about them. First, if you own a restaurant, you likely want to rent a machine, not buy one, because they seem to break down pretty often in industrial use where they run all the time.
Let’s look at the various machine types.
The simplest machine is just a freezer with trays in it. I remember the old aluminum trays that had the big lever on them to release the cubes. The lever tended to interfere with the toothpicks when I froze hawaiian punch into cubes… And I remember getting home with the ice bucket from the Holiday Inn so we could have a cool place to keep the cubes. It seemed like it was always my job to refill the trays, spilling water along the way.
Then, when I got my own place and bought a fridge, I found out about automatic ice makers! These wonderful gadgets sit in the freezer compartment and make those awful little crescent shaped pieces of ice that seem to perfectly fit the rounded part of the glass and block your drink from pouring smoothly. And they are always cloudy, even when made with filtered water.
So why are most home made ice cubes cloudy? Sure, the water quality has some to do with it; but most cloudiness is from entrained air that comes out of solution as the water is chilled. If you use reverse osmosis water it is better. The ice isn’t dirty, just ugly.
So how about those under counter ice makers? Some of them are a freezer with a dreaded crescent shaped ice maker inside. These are cheap and pretty reliable, but they make those awful, cloudy, crescent shaped cubes…
The better under counter ice makers are all basically the same machine. It is not a freezer, but it is a well-insulated box, and it has a compressor, and a drain. If your ice maker doesn’t need a drain hookup, then it is one of the cheaper ones that makes those awful crescent things.
The good ones have a plate in them that gets very cold. They fill a tub with water, and then start circulating the water over a very cold plate. After a certain amount of time, a slab of ice forms on the plate. Some of the machines have a thickness control, which just keeps the plate cold longer, to make a thicker slab. Once an appropriate thickness is created, the machine reverses the coolant flow from the compressor and starts heating the plate. This melts the slab off of the plate, and it slides off the plate onto a wire grid. A small electric current flows through the grid and melts the slab into the characteristic small, flat, square cubes. These cubes will be very clear, because rather than freezing still water into ice and allowing the air entrained to come out and stay in the ice, the water is recirculated over the plate as it freezes, so the air is released without staying in the ice. If you use reverse osmosis water rather than filtered water, the cubes are crystal clear.
Once the wires melt through the slab, the ice falls into the ice bin. The bin is well insulated, but the machine is not a freezer; so the ice melts continuously. As such, these machines make ice continuously, constantly turning over the ice supply. So there is never that “old ice” in the bottom. That’s why they need the drain, since the ice melts all the time.
The insulation is good enough that the machine does not run all the time, it has a sensor near the top of the bin that detects when the bin is full, and shuts off the cycle. Our machine runs for perhaps an hour or two per day, when we are using a normal amount of ice. The machine can make a slab of ice in about 20 minutes.
These machines have many failure modes: They have a fan that is controlled by the circuit board, and it fails sometimes. Sometimes the circuit board fails. The compressor can give up (expensive). The sensors can die; the ice melting wire can break. I have had most of these problems over the last 10 years of living with my ice machine, and I have gotten pretty good at repairing it. The compressor failed once under warranty and I let THEM replace that, but I know I can do that, too. It would cost about $300; a new ice machine is near $1,000. Sometimes you can get last year’s model at Sears for $600. Ours is a kitchenaid, but they all work the same way, and many of the parts are interchangeable.
So now you know all about ice machines!