Cubic feet per minute (CFM) is a measure used for efficiency kitchen vent hoods fan. There are many factors that determine how much CFM you need: a) the size of your kitchen, b) British Thermo Units (BTU) qualification of its cuisine, which is a measurement of heat production, c) the number of burners your stove, d) the type of food being cooked, ie, greasy dishes. When choosing an air extractor, calculate the CFM required for ventilation hood.
Measure the size of kitchen vent hoods. Get the sizes for width, length and height, using tape. Multiply all three numbers to get the total area, in cubic feet. According to the requirements of the building code ventilation Institute cookers must be at least 15 air changes per hour (ACH) in order to comply with the code. This means that for every hour, the fan would have to spend at least 15 times the amount of air in rooms of any particular size. Multiplying the number of your kitchen area of 15, you must give a number. From CFM measured by minutes, divide that number by 60 to get your initial CFM.
Check with the manufacturer of your stove or locate the label on the stove, you should give the total production of BTU. Add 100CFM for each 10,000BTU. For example, if your total BTU stove (which appears on the label) is 20,000, then add 200. Add a number of CFM Initial Step 1 to the number obtained in Step 2, for the total amount necessary for CFM kitchen vent hoods.