Controlling cooking odors, grease and steam requires a properly designed and ducted fan and range hood to evacuate cooking air quietly and quickly. It is especially important to properly ventilate gas stoves because natural gas or propane produces a significant amount of water vapor when burned, in addition to noxious combustion products. Cooking air must be vented to the outdoors to remove this indoor pollution and potential health hazard. Simply recirculating the air may filter out grease, but the cooking moisture, odor and fumes will remain inside your home. Size and airflow requirements will vary depending on the size of the kitchen, the size of the cooktop, the type of fuel and Btu heat output of the stove. For larger systems, it is also important to consider make-up air to replace the air exhausted from your home. Your HomeAire Dealer can provide specific recommendations for your home based on your lifestyle and cooking appliances.