Hvac Return Duct Sizing Chart

Residential duct sizing guide the following duct sizes are based on a fraction drop of 10 inches per 100 feet of lineal duct.

Hvac return duct sizing 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. Particle diameter strainers and filters mesh size vs. Return a return draws air into a return duct system with negative pressure compared to the space usually via a fixed grille but. Always place return ducts as far away from the supply air vents as possible.

Duct system sizes and airflow quick chart created date. First let s define some terms. The chart assumes the blower motor and total effective length of the duct system to be adequate for a 1 friction rate. Calculations are for 60 f dry air at sea level from 5 to 3000 cfm approximately standard air which is 0 075lb da ft.

This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. 4 ton unit x 144 square inches 576 squared. To insure proper distribution of air volume dampers must be used. 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.

The chart should not be used to design complete duct systems. 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. Rectangular duct is rounded up to the nearest 1 4 inch. Ventilation systems for ventilation and air handling air change rates ducts and pressure drops charts and diagrams and more.

Larger volumes or higher static pressures should be dealt with on an individual. Therefore your return air duct and grill size will be 24 by 24 inches tip. Air intakes and outlets ventilation systems air intakes and outlets rules of thumbs. The square root of 576 is 24.

The sizing chart is designed for estimating the airflow in an average system. Properly sizing and installing your air conditioning system are important in making sure your air.