Return Air Duct Chart

Metal ductboard flex size by.

Return air duct chart. Air intakes and outlets ventilation systems air intakes and outlets rules of thumbs. Never locate ducts at the end of the trunk line run. Step 4 calculate the square root of the total. Duct system sizes and airflow quick chart created date.

4 ton unit x 144 square inches 576 squared. Convert rectangular duct to round equivalent. 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 round duct size estimate. Rectangular duct is rounded up to the nearest 1 4 inch.

The square root of 576 is 24. Particle diameter opening size. Particle diameter strainers and filters mesh size vs. Diameter of duct x 3 14 return air duct in square inches.

Table 4 2 return air duct installation sizes based on 05 inches of pressure drop per 100 ft round duct rectangular duct cfm dia. In wg duct tel. 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. 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.

Calculations are for 60 f dry air at sea level from 5 to 3000 cfm approximately standard air which is 0 075lb da ft. Ventilation systems for ventilation and air handling air change rates ducts and pressure drops charts and diagrams and more. Therefore your return air duct and grill size will be 24 by 24 inches tip. Return air cfm must be equal or greater than supply air cfm.

Most technicians are skeptical about these numbers especially on the return air side of the system. Dampers on take off duct runs allow for adjustments of air distribution. In order to maintain velocity reduce duct size. Friction rate velocity friction rate.

Sl rectangular td 50 5 8 x 6 75 5 8 x 6. Include fittings in the duct tel enter either. Tees split but do not reduce and an appropriate reducer must be added.