Cubic feet per minute (CFM) is a measurement used to percentage exhaust fans. Exhaust fans come in a discrepancy of sizes and styles dependent on their intended practice. When determining the Correct CFM for a scale hood fan, there are three factors to excogitate: a) the dimensions of the scullery existence, b) the BTU (British Thermal Units) and aim of your range, and c) the dimensions of duct donkeywork between the hood and the gone air. Kitchens demand 15 Air Changes per Date (ACH) in form to be compliant with the Residence Ventilating College's building edict requirements. CFM is measured in minutes so now divide that number by 60. Divide 9600 by 60 to get 160CFM as a starting point for the range hood CFM rating.2. Determine the number of BTU (British Thermal Units-the standard measure for range size) produced by your range and add 100CFM for every 10,000BTU.
Embark on by measuring the magnitude of the space. You definitely must an accurate length, span, and heighth of the field that the reach hood Testament function. Drive the book of air inside the cookhouse by multiplying all three of the numbers cool. Lets appliance a extent that is 8 feet Broad by 10 feet far-reaching by 8 feet hovering which equals 640 cubic feet of air that the fan Testament get to move at least 15 times in an hour so multiply the amount of air (640 cubic feet) by 15 to get a total of 9600 cubic feet of air. Pursue these directions to calculate the Correct CFM for a area hoods in your down home.
Instructions
1.In our example, we will use a 20,000BTU range located directly under the range hood. Thus we will need to add 200CFM to our original number of CFM for the hood (160 + 200CFM) for a total of 360CFM to be compliant.
3. Measure the duct length that the range hood will have to overcome of stale air. Use values from the table in the Resources below to determine the exact duct length footwise. In our example, we have a simple duct run that is 4 feet of 6-inch straight pipe to a 90- degree elbow, to a run of 3 feet of straight pipe and a cap. Calculated this looks like: 7 feet of straight pipe + 20 feet for the elbow + 40 feet for the cap = 67CFM. Add that result to our total CFM (360CFM + 67CFM) to get a calculated CFM rating for your range hood of 427CFM. In order to be compliant, you would need to install a fan in the range hood that had a rating of at least 430CFM or greater.
