Return Air Duct Chart

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.

Return air duct chart.

Most technicians are skeptical about these numbers especially on the return air side of the system. 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. Therefore your return air duct and grill size will be 24 by 24 inches tip. Convert rectangular duct to round equivalent.

Calculations are for 60 f dry air at sea level from 5 to 3000 cfm approximately standard air which is 0 075lb da ft. Sl rectangular td 50 5 8 x 6 75 5 8 x 6. 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. Include fittings in the duct tel enter either.

Friction rate velocity friction rate. In order to maintain velocity reduce duct size. Step 4 calculate the square root of the total. The square root of 576 is 24.

Never locate ducts at the end of the trunk line run. Metal ductboard flex size by. In wg duct tel. Particle diameter opening size.

Duct system sizes and airflow quick chart created date. 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. 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. Dampers on take off duct runs allow for adjustments of air distribution.

Diameter of duct x 3 14 return air duct in square inches. Tees split but do not reduce and an appropriate reducer must be added. Particle diameter strainers and filters mesh size vs. Return air system no.

Table 4 2 return air duct installation sizes based on 05 inches of pressure drop per 100 ft round duct rectangular duct cfm dia. Return air cfm must be equal or greater than supply air cfm. Rectangular duct is rounded up to the nearest 1 4 inch.