Most technicians are skeptical about these numbers especially on the return air side of the system.
What size duct do i need for 1000 cfm.
The minimum duct sizes and recommended duct sizes based on a hood fan s cfm rating are as follows.
Minimum duct size of 8 recommended duct size of 10 12.
One six inch round duct is good for about 120 cfm a six inch duct carries about 150 cfm and eight inch carries about 200 cfm of cool air.
Shr 80 to 85 19º td ave.
Tees split but do not reduce and an appropriate reducer must be added.
Referring back to the chart under the 4500 cfm column 1500 cfm is not listed but is close to the.
Added together there is a total of 615 885 1500 cfm coming together.
The smaller the duct size the less cfm you need and the larger the duct size the more cfm you need.
Humidity 400 cfm ton shr above 85 17º td low humidity 450 cfm ton cfm total heat equation cfm btu hr 4 5 x h x acf sensible load 1 08 x td x acf friction rate used in duct calculators friction rate pressure drop is the available static pressure asp allocated to the duct work.
In order to maintain velocity reduce duct size.
Never locate ducts at the end of the trunk line run.
A 0 to 400 cfm fan requires a 4 inch minimum duct size but a 6 inch duct is recommended.
How do you figure what size branch you ll need.
Minimum duct size of 7 recommended duct size of 8 10 901 1200 cfm.
The 6 pipe needs 885 cfm at the same velocity of 4500 fpm.
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.
The 5 pipe carries 615 cfm at 4500 fpm see chart above.
Return air cfm must be equal or greater than supply air cfm.
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.
Minimum duct size of 4 recommended duct size of 6 401 600 cfm.
Your home needs ducts that support this much airflow.
The minimum recommended duct size is 6 for 0 400 cfm range hoods.
Divide your number by 10.
Minimum duct size of 6 recommended duct size of 8 601 900 cfm.
A rule of thumb says ducts should carry 400 cubic feet per minute cfm of air for every one ton of cooling.
Dampers on take off duct runs allow for adjustments of air distribution.
