Hvac Return Duct Sizing Chart

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.

Hvac return duct sizing chart. Ventilation systems for ventilation and air handling air change rates ducts and pressure drops charts and diagrams and more. Most technicians are skeptical about these numbers especially on the return air side of the system. 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. Duct system sizes and airflow quick chart created date.

The chart should not be used to design complete duct systems. To insure proper distribution of air volume dampers must be used. First let s define some terms. Larger volumes or higher static pressures should be dealt with on an individual.

4 ton unit x 144 square inches 576 squared. Return a return draws air into a return duct system with negative pressure compared to the space usually via a fixed grille but. 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. The square root of 576 is 24.

Always place return ducts as far away from the supply air vents as possible. Proper sizing and orientation of grilles registers and diffusers may seem like such a simple thing but it s an area where confusion and mistakes are commonly made. Properly sizing and installing your air conditioning system are important in making sure your air. The sizing chart is designed for estimating the airflow in an average system.

Particle diameter opening size. Particle diameter strainers and filters mesh size vs. Therefore your return air duct and grill size will be 24 by 24 inches tip. This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications.

Rectangular duct is rounded up to the nearest 1 4 inch. Calculations are for 60 f dry air at sea level from 5 to 3000 cfm approximately standard air which is 0 075lb da ft.