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Table 501.4.2 <br />Makeup Air Opening Sizing Table for New and Existing Dwelling Units <br />Notes: <br />A. An equivalent length of 100 feet of round smooth metal duct is assumed. Subtract 40 feet for the exterior hood and ten feet for each 90- degree elbow to <br />determine the remaining length of straight duct allowable. <br />B. If flexible duct is used, increase the duct diameter by one inch. Flexible duct shall be stretched with minimal sags. Compressed duct shall not be accepted. <br />C. Barometric dampers are prohibited in passive makeup air openings when any atmospherically vented appliance is installed. <br />D. Powered makeup air shall be electrically interlocked with the largest exhaust system. <br />Combustion air <br />Not required per mechanical code (No atmospheric or power vented appliances) <br />v/ Passive (see IFGC Appendix E, Worksheet E-1) Size and type 3 inch ridged, 4 inch flex <br />Other, describe: <br />Explanation - If no atmospheric or power vented appliances are installed, check the appropriate box, not required. If a power vented <br />or atmospherically vented appliance installed, use IFGC Appendix E, Worksheet E-1 (see below). Please enter size and type. Combustion <br />air vent supplies must communicate with the appliance or appliances that require the combustion air. <br />Section F calculations follow on the next 2 pages. <br />One or multiple power <br />vent, direct vent ap- <br />pliances, or no combus- <br />tion appliances <br />One or multiple fan- <br />assisted appliances and <br />power vent or direct vent <br />appliances Column B <br />One atmospherically vented <br />gas or oil ap- <br />pliance or one solid fuel <br />appliance <br />Multiple atmospherically <br />vented gas or oil ap- <br />pliances or solid fuel <br />appliances <br />Duct di - <br />ameter <br />Passive opening <br />1-36 <br />1-22 <br />1-15 <br />1-9 <br />3 <br />Passive opening <br />37-66 <br />23-41 <br />16-28 <br />10-17 <br />4 <br />Passive opening <br />67-109 <br />42-66 <br />29-46 <br />18-28 <br />5 <br />Passive opening <br />110-163 <br />67-100 <br />47-69 <br />29-42 <br />6 <br />Passive opening <br />164-232 <br />101-143 <br />70-99 <br />43-61 <br />7 <br />Passive opening <br />233-317 <br />144-195 <br />100-135 <br />62-83 <br />8 <br />Passive opening <br />w motorized damper <br />318-419 <br />196-258 <br />136-179 <br />84-110 <br />9 <br />Passive opening <br />w/motorized damper <br />420-539 <br />259-332 <br />180-230 <br />111-142 <br />10 <br />Passive opening <br />w/motorized damper <br />540-679 <br />333-419 <br />231-290 <br />143-179 <br />11 <br />Powered makeup air <br />>679 <br />>419 <br />>290 <br />>179 <br />NA <br />Notes: <br />A. An equivalent length of 100 feet of round smooth metal duct is assumed. Subtract 40 feet for the exterior hood and ten feet for each 90- degree elbow to <br />determine the remaining length of straight duct allowable. <br />B. If flexible duct is used, increase the duct diameter by one inch. Flexible duct shall be stretched with minimal sags. Compressed duct shall not be accepted. <br />C. Barometric dampers are prohibited in passive makeup air openings when any atmospherically vented appliance is installed. <br />D. Powered makeup air shall be electrically interlocked with the largest exhaust system. <br />Combustion air <br />Not required per mechanical code (No atmospheric or power vented appliances) <br />v/ Passive (see IFGC Appendix E, Worksheet E-1) Size and type 3 inch ridged, 4 inch flex <br />Other, describe: <br />Explanation - If no atmospheric or power vented appliances are installed, check the appropriate box, not required. If a power vented <br />or atmospherically vented appliance installed, use IFGC Appendix E, Worksheet E-1 (see below). Please enter size and type. Combustion <br />air vent supplies must communicate with the appliance or appliances that require the combustion air. <br />Section F calculations follow on the next 2 pages. <br />