Duct Sizing Hvac Cfm Chart

To insure proper distribution of air volume dampers must be used for all branch runs.

Duct sizing hvac cfm chart.

If a room is 250 square feet the result will be a duct size of 8 inch round. Note also the return air grille sizing formula at the top of the chart. The chart is based on metal duct. Flex duct has a higher pressure drop and as such may require the size shown on this guide be increased by 1 round size for up to 800 cfm and 2 round sizes.

This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Larger volumes or higher static pressures should be dealt with on an individual job basis. You can also do this by checking for them online or by using a manual that is sold by distributors. Cfm 4 cfm 6 cfm 8 cfm 10 cfm 12 60 6x4 60 4x6 90 4x8 120 4x10 150 4x12 90 8x4 110 6x6 160 6x8 215 6x10 270 6x12.

Calculate the duct size by using a duct calculator. Flex duct 05 on most metal duct calculator round metal pipe 06 on most metal duct calculators field duct sizing chart rectangular sheet metal duct 07 on most metal duct calculators duct size. The chart should not be used to design complete duct systems.