When the sun's burning bright, there's no more welcome noise than the "clink" of ice cubes in a glass. For many kitchens, a refrigerator ice maker is a crucial piece of equipment, every bit as important as a microwave or a toaster. They've been around for as long as those stalwarts, too: the first household ice makers were released in the 1950s, part of a crop of appliances meant to revolutionize modern kitchens. So, given the fact that this feature has woven itself into the fabric of many a kitchen, you might be wondering, how does an ice maker work?
Given the fact that they have a very simple purpose and have been around for three-quarters of a century, you might find it safe to assume that refrigerator ice makers are a solved problem. That very much isn't the case, with many fridge manufacturers doing the equivalent of tossing darts at a corkboard in the hopes of finding the next big thing in convenience. This article explores the different designs and technologies for these systems, the advantages of each refrigerator ice maker type, and their known reliability issues. It's also important to note that this article focuses only on refrigerator ice makers, not separate countertop units, though their overall method of operation is still similar.
Test results
Preliminary Concerns
If you want a fridge that can supply ice on demand, it'll need to be plumbed into your home's water line. Most fridges on the market with ice makers include a water filter to improve the taste of water being run through the water line. That said, they aren't a magic bullet, and do have some limitations: most fridge water filters don't remove odors, and are incapable of dealing with large amounts of sediment. If those are significant issues in your home, we'd advise consulting with a professional plumber and potentially getting a whole-home filtration system installed.
Ice Maker Placement
If you were to only focus on the wide range of ice maker locations found in contemporary fridges, you'd think that the ideal location for an ice maker is still up for debate. Some go for in-door units, while others put the whole assembly inside the freezer cabinet. We'll save you the trouble: if you need an ice maker, the best place for it to be is in the freezer, at least from a longevity perspective.
In-door ice makers need to maintain an independent microclimate, as they're usually butted up right against the refrigerator cabinet, which is too warm for ice formation to occur. This requires a whole heap of added complexity and added gaskets to insulate the ice maker from the rest of the fridge cabinet. Then there's the obvious hit to fresh food storage capacity: in-door ice makers take up some of the most valuable real estate in a fridge along the top shelf and in the door of the unit. Since ice is typically dispensed through the door, accessing large amounts of ice in a hurry can be a hassle.
The same can't be said for in-freezer units, which don't require being placed within an insulated compartment, usually speeding up the ice production process. They are typically much faster with greater overall capacity, though this disadvantage can also apply to ice makers built into freezer doors, too: see the difference in maximum ice capacity between a few different fridges below.
| Refrigerator | Type | Ice Maker Location | Maximum Ice Capacity | 24-Hour Ice Production Rate |
|---|---|---|---|---|
| Bosch 800 Series B36CT80SNS | French-door | Freezer Compartment | 4,328 g (9.54 lbs) | 1,472 g (3.25 lbs) |
| LG LRFLC2706S | French-door | Freezer Compartment | 3,950 g (8.71 lbs) | 1,467 g (3.23 lbs) |
| Frigidaire FRSS2623AS | Side-by-side | Freezer Compartment | 3,775 g (8.32 lbs) | 1,499 g (3.30 lbs) |
| LG LTCS20020S | Top Freezer | Freezer Compartment | 3,405 g (7.51 lbs) | 2,457 g (5.42 lbs) |
| Bosch 500 Series B36FD52SNS | French-door | Fridge Door | 1,796 g (3.96 lbs) | 1,213 g (2.67 lbs) |
| KitchenAid KRSC703HPS | Side-by-side | Freezer Door | 2,376 g (5.24 lbs) | 1,780 g (3.92 lbs) |
The main sacrifice is convenience: you won't just be able to stick a glass or bottle under the dispenser and fill it with ice. For many cheaper models, an ice maker can be sold as an add-on accessory when buying the fridge from a retailer, or can be purchased separately, as is the case for the GE GTS22KGNRWW and its own ice maker. This can be a pretty massive boon from a general serviceability aspect: if an ice maker of this type stops working, it's much simpler to remove the assembly and swap in a new ice maker than it would be if it were built into the appliance itself.
How An Ice Maker Works
Any ice maker functions according to a three-step process:
- Freeze
- Harvest
- Fill
In the first freezing stage, water is piped into the ice maker mold from lines running around the fridge. The water valve remains open for a pre-set amount of time, just enough to fill the ice mold, using a solenoid-actuated valve. The exact point where the harvesting phase begins is governed by a bimetal thermostat or a thermistor, which closes and forms a complete circuit once the water inside the mold has frozen solid. Some fridges, especially Samsung models like the Samsung Bespoke RF24BB6600QL, run a control algorithm that lowers the temperature in the cabinet by a few degrees to shorten the freezing process. This can accelerate ice formation speed, but it's worth keeping in mind if you're frequently serving ice cream or any other sweet treat and have noticed that it's a little harder to scoop than usual.
The harvesting stage is fairly self-explanatory: ice is extracted from the mold and dumped into the tray. That said, the actual extraction mechanism is where you'll see the biggest differences between refrigerator ice makers; more on that later.
Finally, the fill phase engages once the tray has been completely emptied of ice. The mechanism through which this phase is engaged can also vary. With ejector-style units, a separate shut-off arm gradually drops downward as ice is transferred from the mold to the tray. Once it falls back to its lowest position, which can only occur if the tray is completely emptied of ice, it closes the water valve solenoid circuit, reopening the water line and restarting the entire process.
Some ice makers, typically fridge and freezer door units, have an additional ice-crushing function, where ice is directed towards a motorized ice-crushing mill. These devices aren't standardized in general function, so you'll see a lot of variation in terms of what your crushed ice may look like here: some will reduce ice to jagged chunks, while others will produce delicate, flaky ice. In any case, it's important to note that the vast majority of ice crushing systems won't be able to produce powdered ice, like a blender would.
Ice Maker Types
Broadly speaking, there are two main ice maker types: ejector-style and twist-tray. With an ejector-style unit, the mold is made of metal and is encircled by a heating element that melts the outer layer of ice. From there, the plastic scraper arms, which fit into cut-outs in the mold, rotate and eject that ice out and dump it into the tray. Meanwhile, a twist-tray ice maker works under the same principle as a "manual" ice tray: a flexible plastic mold is twisted until the ice is forced out.
Of the two ice maker types, ejector-style units tend to be more robust: aside from the scraper arms, most of the main components are typically made of metal. Meanwhile, the molds of a twist-tray unit are made of plastic, all the better for being able to flex. That said, these plastic molds can become brittle from a combination of regular mechanical stress and the thermal shock of water freezing into ice. These molds can eventually crack and break, just like one of those aforementioned old-school ice cube trays. That's not to say that ejector-style units can be completely fault-free either: should the ice in the mold freeze too hard, the plastic scraper can break against the surface of the ice. In either of those situations, it's typically cheaper and easier to replace the entire ice maker than it is to swap in a new part. As stated earlier, simple top-freezer models with optional ice makers can make this process quite simple.
Conclusion
We hope this was an enlightening rundown on refrigerator ice makers. If you're looking for a broader overview of how refrigerators work, check out our article on the topic. Conversely, if you're already shopping for a refrigerator and want to know a bit more about the pros and cons of different sizes and types, go ahead and check out our articles on refrigerator types and refrigerator sizes.