Ventilation systems for ventilation and air handling air change rates ducts and pressure drops charts and diagrams and more.
Standard duct sizes inches.
Rectangular duct sizes inches mm x mm equivalent diameter round duct sizes d e inches mm velocity in equivalent round duct v ft min m s friction loss inh 2 o 100 ft duct pa 100m x x 80 0 04 3 x 7 4 x 5.
In order for your forced air furnace to work properly you have to have the right sizes of duct vents in each room expelling air.
This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications.
Sizing is based on airflow needs per cubic foot per minute as well as velocity.
Air ducts velocity diagram air flow volume duct.
The hvac model that you re interested in should offer information regarding the maximum airflow per cubic foot per minute or cfm to help you determine adequate.
The following duct sizes are based on a fraction drop of 10 inches per 100 feet of lineal duct.
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.
100 0 045 4 x 6.
Duct sizing how to size ductwork.
The minimum duct sizes and recommended duct sizes based on a hood fan s cfm rating are as follows.
Duct system sizes and airflow quick chart created date.
The furnace s british thermal units btus will help calculate the size it needs.
A 0 to 400 cfm fan requires a 4 inch minimum duct size but a 6 inch duct is recommended.
One is made from standard galvanised steel the other from fibreglass the pressure drop over a 10m distance for this example is around 11 pa for the galvanised steel and 16 pa for the fibreglass.
120 0 05 4 x 7 5 x 6.
Air ducts sizing air flow and required duct area.
Energy efficient duct fittings.
Rectangular or square ducting comes in standard sizes ranging from 3 by 7 inches to 35 by 40 inches.
Sizes of circular ventilation air ducts.
