Ideally, the rangehood should be at least the same size as the cooktop, or preferably larger, to effectively capture and remove cooking fumes, smoke, grease, and odors. The primary purpose of a rangehood is to vent out these byproducts produced during cooking, ensuring a cleaner and healthier indoor environment.
A rangehood that is too small compared to the cooktop may not be able to cover the entire cooking area adequately, leading to incomplete ventilation. This could result in lingering odors, grease buildup on surfaces, and potentially lower air quality.
For optimal performance, it's recommended to choose a rangehood that matches the width of the cooktop or extends beyond it on both sides. For example, if you have a 30-inch cooktop, a rangehood that is 30 inches wide or wider would be appropriate.
Additionally, the power of the rangehood (measured in cubic feet per minute, or CFM) should be sufficient for the size of your kitchen and the intensity of cooking you do. Higher CFM ratings are generally better for more extensive and high-intensity cooking, but keep in mind that the rangehood's noise level will also increase with higher CFM ratings.
In summary, a rangehood that matches the size of the cooktop or is larger, along with an appropriate CFM rating, will help ensure efficient ventilation and a pleasant cooking experience.