Return Air Duct Chart

Tees split but do not reduce and an appropriate reducer must be added.

Return air duct chart.

Therefore your return air duct and grill size will be 24 by 24 inches tip. Return air system no. 810 cold air boot collar duct 45 65 el air flow dynamics duct sizing reference guide supply or return duct size capacity 09 to 10 pressure drop per 100 el cfm round no. Sl rectangular td 50 5 8 x 6 75 5 8 x 6.

The square root of 576 is 24. In order to maintain velocity reduce duct size. 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.

Dampers on take off duct runs allow for adjustments of air distribution. Include fittings in the duct tel enter either. Return air cfm must be equal or greater than supply air cfm. In wg duct tel.

Never locate ducts at the end of the trunk line run. Metal ductboard flex size by. Duct system sizes and airflow quick chart created date. 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.

4 ton unit x 144 square inches 576 squared. 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. Particle diameter opening size.

Wxh wxh wxh wxh wxh wxh wxh wxh 80 6x6 7x5 9x4 90 7x6 8x5 10x4 100 7 8x6 9x5 11x4 125 7x7 9x6 11x5 13x4 150 8x7 9x6 12x5 15x4 175 8 8x8 9x7 10x6 13x5 17x4. Particle diameter strainers and filters mesh size vs. Diameter of duct x 3 14 return air duct in square inches. Calculations are for 60 f dry air at sea level from 5 to 3000 cfm approximately standard air which is 0 075lb da ft.

Friction rate velocity friction rate. Table 4 2 return air duct installation sizes based on 05 inches of pressure drop per 100 ft round duct rectangular duct cfm dia. Most technicians are skeptical about these numbers especially on the return air side of the system.