Burners on gas cooktops and rangetops have come a long way over the years. They can simmer so low as to melt chocolate and hold it in that melted state for hours. Yet that same burner can boil up to 4 quarts of water in a little more than 10 minutes.

The cooktops available today can come in a variety of sizes and styles, differing from manufacturer to manufacturer. While different in many ways, at their core, gas burners found on cooktops and rangetops are very similar. Gas flows from a main gas valve to the burner through a venturi tube, which allows the gas to properly mix with air for clean combustion. The mixture flows into the burner where it is lit by an igniter. From this stepping off point, however, technology begins to vary.

Fisher & Paykel’s CookSurface features three burners in a row, each with its own hot surface ignition.

Manufacturers now have a choice of igniters, for instance. Rarely is a pilot light system utilized. Today, manufacturers use direct spark ignition systems, though hot surface igniters have shown up on a few high-end appliances. A spark system uses high voltage sparks that are generated between the electrode and the burner to light the gas. A hot surface igniter is usually made of ceramic-based materials. An electrical current is sent to the igniter, causing resistance from these materials to heat the tip of the igniter. Traditionally, such igniters took as long as 25 seconds to reach ignition temperature, making them unsuitable for cooktop use where consumers expect to see fire almost immediately. However, within the past few years, innovative hot surface igniters have been developed that can reach ignition temperature in as little as three to four seconds, making that approach more feasible.

Thermador’s Star Burner is designed to evenly heat cooking vessels.

One of the manufacturers that have taken advantage of such new hot surface ignition technology is New Zealand-based Fisher & Paykel, which has U.S. offices in Huntington Beach, Calif. The company spent four years developing a novel gas cooktop under the name Project Luna, which was recently rolled out as the CookSurface. The stylized cooktop, which has a black reflective ceramic top, has integrated three sealed burners that, when activated, rise up from below the surface and are lit by hot surface ignition. When not in use, the burner and pan support pins retract below the surface, nearly flush, allowing for an attractive, flat cooktop. The product is available in Australia, Asia and Europe, and is expecting to receive CSA approvals for North America by early next year.

The company worked with a burner supplier, which they declined to name, to custom design the hot surface ignition system. The igniter features a 1/4-in. x 1/16-in. x 3/8-in. long tip that ignites the gas in less than 3 seconds. A thermocouple sensor monitors the presence of a flame and will reignite if it doesn’t sense a flame. Each burner has its own ignition and flame sensing system. In addition, the igniter offers good corrosion resistance, is strong, and lights the gas without the associated noise of a direct spark ignition system, says Stephen Bruce, product manager for Fisher & Paykel.

According to the company, the Aero burners on the CookSurface offer precise linear flame control accomplished by an integrated fan in the burner system. The variable speed fan delivers an optimized mix of oxygen and gas to the burner, which helps to control both the low simmer and high flame settings.

The second feature that sets this CookSurface apart from other technologies is the rotary lift system that raises and lowers the burner and the hidden pan supports for each of the three burners. When it reaches full height, the pins lock into place and will not retract while a flame is present or if the pan supports or burner cap are hot enough to potentially damage the unit. Fisher & Paykel uses a temperature sensor to control this safety feature.

Because the burner system rises and retracts, the designers needed to ensure that none of the gas lines would crimp. The solution, they say, was to not have the gas lines move at all. The base of the burner, to which the gas lines are attached, stays in place. Instead the burner head telescopes up for cooking.

While other technologies may not be as unusual in scope as the CookSurface, they each work to satisfy the most important aspect of a cooktop — providing a full range of heat from a low simmer to very high heat. The easiest way to accomplish this is to have dedicated burners, but that limits the consumer’s ability to concurrently cook multiple items that might require the same heat level.

George Simadiris, vice president of engineering for Dacor, Huntington Beach, Calif. says that his company’s new Renaissance cooktops have a wide range of heat settings, operating at the equivalent of 350 BTUs up to 18,000 BTUs. He says this wide range of outputs is accomplished by means of a fan system controlling the flow of gas to the burner.

Fagor’s new 28 in. gas cooktop features 5 burners, including one Triple Crown burner, which has three concentric rings of flame for even heat distribution. Each burner has an individual spark generator.

BSH Home Appliances, Huntington Beach, Calif., takes a different approach for achieving low simmer levels on its Thermador brand cooktops whose ExtraLow simmer feature is achieved by cycling the flame on and off, permitting it to go as low as 200 BTU. For a very low simmer, over a 60-second period the gas might be on for 10 seconds and off for 50 seconds. For a higher simmer, the gas might be on for 30 seconds and off for 30 seconds. The maximum at the upper end of the heat range for their new cooktops is 18,000 BTUs burner.

These extreme ranges of heat are good for the consumer, but were a challenge for designers. At the high end, when a lot of gas is flowing through the burner ports, flame lifting can be a problem. This occurs when not enough air is mixing with the gas causing the flame to ignite higher, nearer to the cooking utensil. At the low end, the problem can be flame out. In this case, the flame gets extinguished either because of inconsistent gas flow or because the flame was so small that ambient air blew it out. (Preventing flame out at lower settings is even a bigger challenge in ranges, where the opening and closing of an oven door can provide enough air disturbance to blow out a small flame.)

Cooking appliance designers have come up with different ways to solve these problems, from using fans to improving burner designs. On Thermador’s spark-ignition Star Burners, for example, the design overcomes the problem of flame lifting with a small overhang on the burner cap that allows for air between the cap and the burner base. By creating this space, Thermador has allowed room for combustible air to exit and enter, creating the correct pressure to avoid flame lifting, says Malte Peters, product manager.

Thermador and many other manufacturers offer a safety feature for when the flame goes out. Typically, this is a thermocouple sensor that senses the presence or absence of flame. Dacor cooktops feature the PermaFlame technology, which Simadiris says uses a “form of thermocouple.” The igniter’s tip not only sparks the gas to create the flame; it also acts as the flame sensor. The sensor is constantly checking the burner and if it senses the flame, it sends a signal to the ignition controller that a spark is not needed. If there is no flame, it sends a signal that a spark is needed. This automatic reignition takes less than three seconds.

A sealed burner from Fagor is made up electronic igniter (center) and the burner cap (right). Disassembling these pieces allows for easy clean up of spills.

An alternative safety approach to reigntion is to simply shut off the gas if the flame goes out. This method can be found on the Siemens avantGarde™ 36-in ceramic glass “gas on glass” cooktop. In this case, the flame needs to be manually reignited.

Over the years, most manufacturers have switched from open (atmospheric) burners to sealed burners, which are designed to eliminate the gap between the burner and the burner tray that is found on open burners. This gap can allow liquid spills to run into the interior of the cooktop, making it difficult to clean. The sealed burners also offer a more uniform and elegant design compared to an open burner that allows the user to see more of the cooktops less attractive interior, says Simadiris.

However, atmospheric burners are not extinct, even at the upper end of the residential cooktop market. Companies such as Viking Range of Greenwood, Miss., offers open burners on their high-end appliances for consumers and kitchen designers who want open system burners. Both types of burners provide exceptional cooking performance, so the difference between them is not in performance, but in cleanability, says Jeff Clemson, chief engineer — cooking products for Viking. It may come down to how often spills occur. Most commercial kitchens, where spills can be frequent, use open burner ranges because they are easier to breakdown for cleaning and the same is true about the Viking open burner ranges. The grate supports and burner bowls remove for easy cleaning in the dishwasher or sink. However, some customers make less of a mess when cooking and prefer the sealed burner configuration as all spills are contained on the surface. Viking offers a one-piece tooled and porcelainized cooking surface for ease of cleaning on the sealed burner tops, he says.

In addition, some believe that open burners burn hotter than sealed systems because of the additional air that surrounds an open system. (That may have been true at one time, though those that offer sealed burners say that new designs now optimize the distance from the burner ports to the grate to increase airflow and minimize or eliminate this consideration.)

The Fisher & Paykel CookSurface has retractable burners. When not in use, the burner retracts nearly flush to the surface (left). When in use, the burners and pan support pins rise up for cooking (right).

Sealed burners are also sometimes used to improve simmering. Viking for instance offers the VariSimmer system. When adjusted to the lowest possible setting, the VariSimmer™ system flame is actually underneath the burner cap, heating only the cap without any flame hitting the pan, says Clemson. This allows for a very gentle simmer because there is no direct flame on the cookware. The simmer setting is variable because the right amount of heat to simmer a 2-qt. saucepan is different than the amount of heat needed to simmer an 8 qt. stockpot, he says.

Using the correct amount of heat, and having it uniformly distributed under a pot or pan is another key to today’s burner systems. Thermador was one of the first to address this with its unique five-point, star-shaped burner. Malte Peters, who in addition to working for Siemens also serves as the cooking product manager for Thermador, says this shape helps deliver 56 percent more heat evenly to the bottom of cookware as compared to traditional round burners.

Fagor’s triple ring burner is another example of a burner configuration that improves heat distribution. The triple-crown burners, with its three concentric flame outputs, can be used at low, medium and high settings. When the burner is first turned on, the innermost burner ring ignites. This is useful for simmering and small cooking vessels. As more heat is needed, the knob is turned and the second ring lights. For the largest pans and the hottest cooking, all three burner rings can be activated. Fagor points to the ease of use and control of this burner.

Human factors is another growing concern for manufacturers. For instance, on Fisher & Paykel’s CookSurface, the cooktop uses audio signals to alert the user that something requires attention or to impart other information. If the user touches the button to retract the burner, but the burner is still too hot, it will beep to alert the user that something is wrong. When cool enough, the unit will automatically retract the burner.

Viking Range offers the Professional Gas and Gas Self-Clean Ranges that feature the SureSpark ignition system.

Another example is Dacor’s new Renaissance Gas Cooktops, which features Illumina burner controls. Each die-cast metal knob has a clear lens insert that emits a blue light. When the burner knob is turned, the blue light indicates that the burner is active, says Simadiris. “If there is a low flame it can be difficult to see the flame, so having the burner emit a blue light is an easy way to indicate that it is on,” he says. A SimmerSafe indicator light also illuminates when the simmer feature is in use.

To improve and preserve long-term aesthetics, Dacor’s line also offers the SmartFlame feature. At specific locations below the “fingers” of the grate, the ports that emit the gas are smaller so the flame that is directly underneath the grates’ fingers are smaller in size. This is done because the by-products of combustion can be corrosive and by reducing the gas emitted and combusted can improve the longevity of the Dacor’s grate. Without it, in only a few months, the color of grate can change and the grate’s life span can be reduced, Simadiris says.

These are just a few examples of how gas cooktops have improved. Today’s cooktops feature better ignition, more control, and more features for the home and professional cook. These features are expected to continue to evolve and the attentions to detail improve over time. The bells-and-whistles that are typically found at the high end of the market are expected to filter down to mid-priced models and lower, as manufacturers look to provide its customers with new features that look and operate better than ever.