Product review (5 stars): READ THIS REVIEW: Emerson/Magic Chef/similar units best/quietest model to buy
Some really straight talk here:

The Emerson&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Emerson-Portable-Ice-Maker/dp/B005L3SEN6/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Emerson Portable Ice Maker</a>&nbsp;and Magic Chef MCIM22TW&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Magic-Chef-Portable-Ice-Maker-White-MCIM22TW/dp/B004ET8DKC/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Magic Chef Portable Ice Maker White MCIM22TW</a>&nbsp;units and those "identical to these" (available on Amazon/elsewhere) (Description: 12"w x14"d x15"h case, curved but relatively flat front case w/diagonal canted front control pad, and left-side drain plug ---- are the best units to buy (reliable, reasonably quiet, good ice volume). We have had problems with the Igloo (narrower case slightly different design and appearance. 9'W x 14"d x 12"h significantly curved front case also with diagonally canted control panel). The narrow case units are generally ~$40 cheaper than the recommended larger square case units. The best of these units will work for at least ~2-years. That's a lot considering they are mechanical devices with a small sealed refrigeration system in them. Commercial grade units are substantially(!) more expensive, use more electricity, and generally require a water supply hookup. When you consider the cost of bagged ice and the hassle of trips to buy/lug it, these units are a time saver - but they are not commercial grade, with the commercial grade price so please keep your expectations realistic.

How to identify the unit you want:

The units come in many colors but generally white or silver. They are similar in appearance and size to counter-top bread makers that were popular years ago (and that made your house smell so good). If you look CLOSELY at the photos of all portable ice makers on Amazon/the Internet (focus on control pad location and shape, drain spout location and shape and cooling intake/exhaust area location and shape, you'll see that there are only a handful of designs but the products are labeled with many different manufacturer names. Like decades-gone-buy-VCRs (remember those before DVDs?) the (VCR) units were manufactured by a handful of manufacturers and labeled with a wide range of names like Magnavox, RCA, Motorola, etc. but the tape internal mechanisms and electronics were were all the same internally or virtually so.

Such is the case with these portable ice makers. Most all of them come from a handful of factories in China. From our experience, we own the Emerson (above), a Magic Chef (12" wide case identical to Emerson except for the name label, also identical to NewAir, Edgestar, SPT, you fill in the brand name...) and a malfunctioning Igloo 9" wide case (looks like a Polar Cube Arctic, Koldfront, Oster, you fill in the brand name...).

It is safe to say as long at the portable ice maker you buy has a front mounted canted oval control pad and looks like the Emerson IM90, Magic Chef MCIM22TW, etc. that's the better choice/the one you want to buy. If is is 9" wide, highly-curved/highly-contoured front, and it looks like a Igloo, Polar Cube Arctic, typically with a bottom drain plug it is best to avoid those even if they are ~$40 chealer. Please note we have simplified this review, there as a few other "odd-ball" higher-priced units out there, we don't have personal experience with and don't specifically mention those. The Emerson and Magic Chef (same unit) with other brand names likely from same Chinese factory are out there.

Most of these portable units will really produce ~20+ pounds of ice in a 24 hour period if you 1) keep emptying the ice bin and 2) keep filling the water reservoir - which is not hard to do.

Finally, a restaurant professional we know stated "Unless you are willing to pay $20,000 for a truly commercial grade ice maker, just buy a good below $300 portable unit. Anything between $300 and $20,000 is going to be marginally reliable." It's been our experience you can find the Emerson IM90 and Magic Chef MCIM22TW or identical discounted in the $120-$170 range, sometimes lower.

How they work:

These portable units are like a mini refrigerator/freezer (these require 120vAC and ~160 watts when cooling circuit is running) and typically have a R134A sealed refrigerant cycle. Some units are louder than others. The Igloo and identical units are loud. The Emerson/Magic Chef-like units are relatively quiet. Then all make some muted noise when the ice cubes fall into the ice bin especially when empty. No big deal. We don't know why so many folks complain about the dropping noise or its suddenness. After all, you can hear ice drops in a full-size freezer compartment when the door is closed...

They have two rows of nine (9) refrigerated cooling rods that dip into a tray of water and the "ice cubes" form on/around the rods. The cubes can be selected as small medium of large, small or large on other units. Then drop off at the end of the freezing cycle. Guests often remark how unusual the half-dome hollow shaped cubes look. Because of their hollow shape (more surface area) they actually cool beverages quickly.

There is a water reservoir under the ice basket (you need no direct water hookup) so you can put these units in the kitchen, backyard, or in an RV anywhere where there is a 120vAC plug. You can fill these self contained units to the "fill line" with filtered or drinking water from the tap/faucet via a pitcher or jug. You will hear a faint motor noise as the internal pump draws water for the reservoir below the ice bin into the freezing tray. Then you will hear the cooling motor/circuit come on to make the ice. When the ice is complete the remaining water is dumped and the ice cubes drop off the rods and are scooped into the ice bin.

The ice bin area is not refrigerated other than the cooling that happens from the ice making. The cases of the units are generally insulated like a mini ice chest. If you do not remove the ice periodically it will melt and become soft and eventually drain back into the reservoir and be made into ice again if the ice basked doesn't fill and trip off the bin full light (that shuts the unit off). The units will also shut off when they run out of water.

How we use them:

Again believe-it-or-not, most of these really produce up to 26 pounds of ice in a 24 hour period if you keep emptying the ice bin and filling the water reservoir. Prior to parties, we use these machines to augment refrigerator ice makers that are generally very slow. You can count of these portable units to produce ~one pound of ice an hour and we just check them periodically and put the ice in large 2-gallon Zip-Lock bags and in a freezer for future use. We also use one in the RV when in campgrounds (when 24/7 120vAC power is available) to augment the built-in freezer/icemaker. They really work nicely.

Hope you found this review/tutorial useful and informative. When you understand how portable ice makers work and their performance characteristics, you'll be a happier consumer.