There are two types of microwave vent systems: recirculating and external. Recirculating vents simply pull the air up into the appliance, run it through a filter to remove impurities, then push it back out into your kitchen. This type of ventilation system is ductless and easier to install, but it doesn’t perform as efficiently as external ventilation.
A microwave’s wattage tells you how much power it has, and more wattage means your food will cook faster and more evenly. You’ll typically see microwaves between 500 and 1,200 watts. Be aware that microwaves with fewer than 700 watts are generally underpowered and add time to the cooking process. These models are a good option for people limited by a budget, looking to save space, or willing to wait a few extra minutes. If you want a fully functional microwave to cook meat and vegetables, look for models with 1,000 watts or more.
Volume control is one of the best extra features a microwave can have, but it’s pretty rare. Some models allow you to mute the beeping, but few microwaves let you adjust the actual volume. We also prefer models that stop beeping when the oven door is opened. It’s a small perk but one that many of our testers appreciated, particularly those who find the beeping annoying.
Uneven heating in microwaved food can be partly due to the uneven distribution of microwave energy inside the oven, and partly due to the different rates of energy absorption in different parts of the food. The first problem is reduced by a stirrer, a type of fan that reflects microwave energy to different parts of the oven as it rotates, or by a turntable or carousel that turns the food; turntables, however, may still leave spots, such as the center of the oven, which receive uneven energy distribution. The location of dead spots and hot spots in a microwave can be mapped out by placing a damp piece of thermal paper in the oven. When the water saturated paper is subjected to the microwave radiation it becomes hot enough to cause the dye to be released which will provide a visual representation of the microwaves. If multiple layers of paper are constructed in the oven with a sufficient distance between them a three-dimensional map can be created. Many store receipts are printed on thermal paper which allows this to be easily done at home.
With a capacity of 2.2 cubic feet, the stainless steel GE Profile microwave boasts a smooth easy-to-clean control panel and a large interior, making it a great model for big families. Seriously, you can heat an entire casserole or pizza on the 16-inch turntable and still have plenty of room to spare. It cooks evenly so you won't find a cold spot in the middle of your ziti and delivers perfectly steamed veggies.
This mistake can happen when buyers get a little too excited. When all you’re focused on is, “When did the microwave come out?” and “Does it have the latest features?”, then you’re ignoring how you currently use microwaves, which is just as important. If you don’t use any of those menu buttons or defrost features now, you probably won’t use them on a new microwave, either. Buy microwaves based on how you like to use them, not on the latest flashy features.
Fast cooking was our top priority — if a microwave can’t prepare a meal speedily, it isn’t the best. Ray Boxman, Professor Emeritus of Electrical and Electronics Engineering at Tel Aviv University, told us microwaves cook fast “because the microwave energy penetrates into the food, in contrast to conventional heating, which only delivers heat to the surface of the food, and a lot of time is needed for the heat to diffuse inward.”
Countertop microwaves are some of the most popular models, and there are many options to choose from. They are quick and easy to install—just plug them in—and you can move them around as needed, making them a top choice for renters. The main downside of countertop microwaves is that they take up valuable counter space, which can be frustrating if you have a small kitchen.
Compared to liquid water, microwave heating is less efficient on fats and sugars (which have a smaller molecular dipole moment). Sugars and triglycerides (fats and oils) absorb microwaves due to the dipole moments of their hydroxyl groups or ester groups. However, due to the lower specific heat capacity of fats and oils and their higher vaporization temperature, they often attain much higher temperatures inside microwave ovens. This can induce temperatures in oil or very fatty foods like bacon far above the boiling point of water, and high enough to induce some browning reactions, much in the manner of conventional broiling (UK: grilling), braising, or deep fat frying. Foods high in water content and with little oil rarely exceed the boiling temperature of water.
Another hazard is the resonance of the magnetron tube itself. If the microwave is run without an object to absorb the radiation, a standing wave will form. The energy is reflected back and forth between the tube and the cooking chamber. This may cause the tube to overload and burn out. High reflected power may also cause magnetron arcing, possibly resulting in primary power fuse failure, though such a causal relationship isn't easily established. Thus, dehydrated food, or food wrapped in metal which does not arc, is problematic for overload reasons, without necessarily being a fire hazard.
There are three main styles of microwaves, and they’re distinguished predominantly by where and how they’re installed. First, there are your standard countertop microwaves, which simply sit on the kitchen counter and are plugged into an electrical outlet. This style is often the least expensive and works best for anyone who lives in a rented home, as they can be moved easily. Countertop microwaves are also a good option if you don’t want to remodel your kitchen to accommodate a built-in style.
For convenience in the kitchen, nothing beats the microwave, which allows you to cook and reheat food from the inside out. After more than 100 hours of research and testing, we think that the Toshiba EM925A5A-BS is the best microwave for most kitchen counters. It’s easy to operate, has a number of express cooking options that heat food quickly and evenly, and even has a mute button so you can cook in silence.
The microwave frequencies used in microwave ovens are chosen based on regulatory and cost constraints. The first is that they should be in one of the industrial, scientific, and medical (ISM) frequency bands set aside for unlicensed purposes. For household purposes, 2.45 GHz has the advantage over 915 MHz in that 915 MHz is only an ISM band in some countries (ITU Region 2) while 2.45 GHz is available worldwide. Three additional ISM bands exist in the microwave frequencies, but are not used for microwave cooking. Two of them are centered on 5.8 GHz and 24.125 GHz, but are not used for microwave cooking because of the very high cost of power generation at these frequencies. The third, centered on 433.92 MHz, is a narrow band that would require expensive equipment to generate sufficient power without creating interference outside the band, and is only available in some countries.
The Toshiba has an easy-to-use digital interface, with one key feature that helps it stand out from much of the competition: a mute button. Since this model doesn’t stop beeping when you open the door, we appreciated having the option to mute the beeping entirely. The Toshiba also has six preset cooking functions for popcorn, potatoes, pizza, frozen vegetables, beverages, and reheating a dinner plate. It has one-touch start controls from 1 to 6 minutes, and a plus-30-seconds button so you can quickly add extra time. Also, its lock function prevents kids from accidentally operating the machine (you simply hold the stop/cancel button for 3 seconds to lock or unlock the door). This model also has several other features that other microwaves we tested lacked, including a memory function (that saves up to three customized cooking times and power levels) and a multistage cooking function (that allows you to set two different cooking times and power levels to operate in succession), but we don’t think most people will use these often.
Formerly found only in large industrial applications, microwave ovens increasingly became a standard fixture of residential kitchens in developed countries. By 1986, roughly 25% of households in the U.S. owned a microwave oven, up from only about 1% in 1971; the U.S. Bureau of Labor Statistics reported that over 90% of American households owned a microwave oven in 1997. In Australia, a 2008 market research study found that 95% of kitchens contained a microwave oven and that 83% of them were used daily. In Canada, fewer than 5% of households had a microwave oven in 1979, but more than 88% of households owned one by 1998. In France, 40% of households owned a microwave oven in 1994, but that number had increased to 65% by 2004.