Round Duct Duct Sizing Chart Cfm

While a duct sizing calculator built for a specific type of ductwork is the best possible method for sizing ducts the attached chart can be used in most single story homes with a centrally located unit and reasonable length duct runs.

Round duct duct sizing chart cfm.

Friction rate velocity friction rate. Velocity duct sizing chart residential main supply trunk ducts non zoned systems target velocity of 800fpm used listed by air quantity round duct size and nearest square duct size 500cfm 11 ø or 10 x 10 1 300cfm 16 ø or 14 x 16 600cfm 12 ø or 10 x 12 1 400cfm 18 ø or 16 x 16. Convert diameter to rectangular equivalent. In wg duct tel.

The rectangular dimensions and the air flow volume are adapted to the equal friction loss. 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 above 800 cfm to insure proper airflow. Larger volumes or higher static pressures should be dealt with on an individual job basis. Sheet metal duct friction loss calculator.

Enter duct airflow cfm duct velocity fpm duct length and the number of bends. The table is based on the ducts friction loss formula. Approximately 400 cfm per ton would require 2 14 flexible return ducts or 1 very short flexible. Include fittings in the duct tel enter either.

Duct system sizes and airflow quick chart created date. The equivalent diameter is the diameter of a circular duct or pipe that gives the same pressure loss as an equivalent rectangular duct or pipe. Failure to do so will result in high velocity and very likely loss of airflow. 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.

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 step one identify the volume of air that will be passing through the duct step two select the duct size from the table that can carry that volume of. Read round duct diameter inches and friction loss per 100 of duct inches of water. This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Convert rectangular duct to round equivalent.