Ac Duct Sizing Chart

Rectangular duct is rounded up to the nearest 1 4 inch.

Ac duct sizing chart. Then we just add up the volume flow rates for all the branches downstream of this. The sizing chart is designed for estimating the airflow in an average system. To do this make sure you start at the main duct which is furthest away.

The chart should not be used to design complete duct systems. A rule of thumb says ducts should carry 400 cubic feet per minute cfm of air for every one ton of cooling. Duct system sizes and airflow quick chart created date.

This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Most technicians are skeptical about these numbers especially on the return air side of the system. 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.

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. To insure proper distribution of air volume dampers must be used. Ductwork chart main duct flow rates.

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. For the main duct g we just sum branches l and i. Calculations are for 60 f dry air at sea level from 5 to 3000 cfm approximately standard air which is 0 075lb da ft.

Larger volumes or higher static pressures should be dealt with on an individual job basis. Then we can start to size the main ducts.