Cfm Per 8 Inch Duct

Duct system sizes and airflow quick chart created date.

Cfm per 8 inch duct.

Looking at my chart i see 420 cfm requires a 8 inch flex duct with a velocity of 1190. Like regular hvac duct flex duct work needs to be sized appropriately in order to flow the air volume which is measured in cubic feet per minute cfm correctly. 320 cfm in 8 duct yields 19in. Design 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 120 10x4 160 8x6 230 8x8 310 8x10 400 8x12 150 12x4 215 10x6 310 10x8 430 10x10 550 10x12 180 14x4 270 12x6 400 12x8 550 12x10 680 12x12 210 16x4 320 14x6 490 14x8 670 14x10 800 14x12 240 18x4 375 16x6 580 16x8 800 16x10 950 16x12 270 20x4 430 18x6 670 18x8 930 18x10 1100.

Sl rectangular td 50 5 8 x 6 75 5 8 x 6 100 6 8 x 6 3 x 10 110 125 6 8 x 6 3 x 12 140 150 7 8 x 6 3 x 14 160 175 7 8 x 6 200 7 8 x 6 250 8 6 x 10 8 x 8 6 x 12 300 9 6 x 10 8 x 8 6 x 12 350 9 6 x 10 8 x 8 6 x 12 400 9 8 x 10 8 x 8 6 x 12. 09 to 10 pressure drop per 100 el cfm round no. Fan works very well. Just under 500 fpm vel.

This equal friction method of duct sizing should be adequate for normal residential furnace. Flex duct allows easy connection from the main duct trunk to the hvac grille. Yields 0 02 friction loss. This fan had one of the highest cfm per dollar.

A typical 3 ton hvac system needs a metal duct about 16 inches round to deliver 1300 cfm. Cfm 4 6 8 10 12 duct inches cfm 50 6 x 4 550 75 6 x 4 675 100 8 x 4 6 x 6 6 100 125 10 x 4 6 x 6 7 125 150 10 x 4 8 x 6 7 150 175 12 x 4 8 x 6 8 175. I usually size duct by friction rate loss velocity per cfm on a duct run not by esp. Could your information be wrong and the rating be airflow in feet per second.

Imo too high a velocity for a residential branch run that we. Ordered it and received it in a few days very quick delivery. If you double the cfm to 320 cfm. Good residential design usually uses velocities of 700 to 900 fpm for supply and 600 to 700 fpm for return.

Air duct also termed as ductulator is a passage that is used to provide fresh air into rooms buildings etc air ducts may be in circular square and in rectangular shapes. Equivalent length at a velocity of 925 feet per minute. Without it there would be tons more labor and material to make that final connection. Is much quieter.

The following duct sizes are based on a fraction drop of 10 inches per 100 feet of lineal duct. Installed it easily was doing a relocation of fan for a different renovation. Everything else the same above. A cfm of 1220 requires a 12 inch duct flex using rigid 1350 cfm needs 16 inch duct.