Flex Duct Hvac Cfm Chart

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.

Flex duct hvac cfm chart.

Use the online duct calculator see references and calculate the needed flex duct size. Read round duct diameter inches and friction loss per 100 of duct inches of water. 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. Enter duct airflow cfm duct velocity fpm duct length and the number of bends.

As systems increase in efficiency the tolerances of how we have always done it will no longer be adequate. Click calculate and you will see the size of flex duct you need for that room. Based on duct diameter. Read duct diameter inches and duct velocity fpm.

The flex duct size may be different than the hard duct that runs to that room. Sheet metal duct friction loss calculator. Enter the desired length of the rectangular duct. This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications.

Rectangular duct is rounded up to the nearest 1 4 inch. Read friction loss inches of water and duct velocity fpm. Larger volumes or higher static pressures should be dealt with on an individual job basis. Select the duct type on the pull down menu.

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. Input the required cfm in the box below that. Include fittings in the duct tel enter either. Enter round duct diameter.

Duct system sizes and airflow quick chart created date. Enter round duct diameter inches duct airflow cfm duct length and the number of bends. Metal ductboard flex size by. Friction rate velocity friction rate.

If ashrae 2013 is selected flexible roughness is 0 003 ft when straight and fully stretched tight at 0 compression adjusted at other compressions otherwise the. 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.