Hvac Flex Duct Calculator

Read duct diameter inches and duct velocity fpm.

Hvac flex duct calculator.

A round duct with a cross sectional area of 0 6m2 has a perimeter of 2 75m a rectangular duct with an equal cross sectional area has a perimeter of 3 87m the rectangular duct therefore requires more metal for its construction this adds more weight and costs to the design. Read round duct diameter inches and friction loss per 100 of duct inches of water. The furnace s british thermal units btus will help calculate the size it needs. Calculations are for 60 f dry air at sea level from 5 to 3000 cfm approximately standard air which is 0 075lb da ft.

Sheet metal duct friction loss calculator. Friction rate velocity friction rate. Use the online duct calculator see references and calculate the needed flex duct size. Enter the desired length of the rectangular duct.

While this may be true in most cases for a metal supply air duct it is not for a metal return nor a 6 flexible duct on supply or return. Input the required cfm in the box below that. Click calculate and you will see the size of flex duct you need for that room. In wg duct tel.

Select the duct type on the pull down menu. This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. 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 duct height net inside dimension in inches. Residential duct sizing guide the following duct sizes are based on a fraction drop of 10 inches per 100 feet of lineal duct.

Larger volumes or higher static pressures should be dealt with on an individual. Metal ductboard flex size by. 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. Convert rectangular duct to round equivalent.

Based on duct diameter. Read friction loss inches of water and duct velocity fpm. The duct vent size will depend on the size of the furnace and the size of your home so you know how many vents you need in each room. Flexible duct round metal pipe 750 1200 14 16 design airflow 50 85 125 1500 2000 180 240 325.

The flex duct size may be different than the hard duct that runs to that room. Enter round duct diameter. 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. Enter round duct diameter inches duct airflow cfm duct length and the number of bends.

Include fittings in the duct tel enter either.