For instance a 2 5 ton system approximately 400 cfm per ton would require 2 14 flexible return ducts or 1 very short flexible 18 duct to move the 1000 cfm required by the 2 5 ton system.
Cfm through 6 round duct.
2000 cfm 0 94 m 3 s of air flows through a 10 x 12 inches rectangular duct.
810 cold air boot collar duct 45 65 el air flow dynamics duct sizing reference guide supply or return duct size capacity 09 to 10 pressure drop per 100 el cfm round no.
This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications.
The velocity in the rectangular duct is.
Sheet metal duct friction loss calculator.
This online air duct calculator is used to calculate the velocity of air flow feet per minute fpm and feet per second fps through any shaped circle square or rectangle ductulator with either diameter sides or area.
Air volume equivalent round air volume 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.
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.
The 0 10 design friction rate is the most commonly passed down tradition of sizing ducts and the reason many assume a 6 inch duct delivers 100 cfm.
Duct system sizes and airflow quick chart created date.
6 supply 100cfm return 75cfm 3 25 x 10 stack 6 oval supply 100cfm retun 75cfm these are the maximum allowable cfms through 6 runout ductwork for heat load calclation purposes from the carrier installation handbook.
The reason setting your duct calculator to 0 10 is such a widely used assumption is because if you look at many slide duct calculators they have a recommended residential setting at 0 10 inch of.
Read round duct diameter inches and friction loss per 100 of duct inches of water.
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.
The friction loss according the table above is 0 81 inches water gauge per 100 ft duct aprox.
Flexible duct round metal pipe 750 1200 14 16 design airflow 50 85 125 1500 2000 180 240 325 525.
New duct sizing chart xls author.
As systems increase in efficiency the tolerances of how we have always done it will no longer be adequate.
Larger volumes or higher static pressures should be dealt with on an individual job basis.