For a period of about 45 years most Americans chose electric cooktops rather than the gas-fired type. The conventional wisdom was that electric appliances were easier to clean and the kitchen stayed cleaner.

As electricity skyrocketed in cost relative to natural gas, a dramatic change in the nation's kitchens began to take place. Many now include at least one gas-fired cooking device.

Once there was cause for complaint about the mess caused by gas cooking. Because exhaust systems were inadequate, a gas kitchen in time became a dirty kitchen.

As exhaust devices improved and rules concerning their installation became law, the gas kitchen became a clean one. Natural gas now is a quick, clean, cost-efficient means of cooking.

If you want to save money, consider gas. There's more to it than replacing a cooktop or range, however.

Extending a gas line can cost more than a good quality cooktop. The modern gas-fired appliance will need to be connected to a 110-volt circuit so that power will be available to operate electric (automatic) igniters and-or control panel lights.

The most important consideration frequently is overlooked a proper exhaust hood (range hood). Chances are the range hood that you used with your electric cooktop will not be sufficient to properly exhaust the additional gasses created by a gas appliance. Federal, state and local laws are rather specific in this area, so for safety's sake, make sure you purchase a range hood that is compatible with the cooktop you decide on.

Even the best of range hoods make quite a bit of noise. By choosing the right size motor and fan type the sound level can be lowered. Better hoods use squirrel cage-type fans as opposed to the more familiar blade-type fan. The squirrel cage fan is cylindrical in shape and supported at both ends to minimize wobbling and noise. If the range hood is rated to exhaust more air than is required, you can use a variable power switch thereby using less power and achieving a quieter operation. Most exhaust fans are quieter when they are not operating at full speed.

Replacing the range hood can be a good idea even if the old cooktop isn't going to be replaced.

Just disconnect the hood from the exhaust duct by removing a couple of strips of duct tape and one or two screws, disconnect the power lead, making sure power is off at the control panel, and remove the four mounting screws that connect the hood to the cabinet above it. These mounting screws are usually located at the four corners of the hood adjacent to the cabinet above and sometimes are hidden by a metal cover that is easily removed.

A range hood can be removed and replaced in less than an hour unless the new hood's exhaust port is a different shape from the old one. Older hoods have round exhaust ports and the newer ones have rectangular exhaust ones. This is solved by using a ready-made sheetmetal conversion boot. The addition of a conversion boot may require shortening the duct in the cabinet to make room for the new assembly.

In most instances the existing exhaust duct will be sufficient in size to handle the flow produced by a modern range hood. But, it is wise to check with the instructions that come with the hood before purchase.

If you're a cooking fanatic and you want the best money can buy, look into a roof-mount motor assembly. The hood is in the kitchen and the exhaust motor is at the other end of the duct on the roof. Don't get near it while wearing a hair piece the force is incredible. One manufacturer makes a 600-cubic feet per minute (cfm) roof-mount model and a 1000 cfm roof-mount model. The 1000 cfm model is several times more powerful than is required for most cooktops.