Duct Requirements

Eugene Silberstein 3

The air distribution system is designed t deliver the correct volume of air (in cubic feet per minute, CFM) to the occupied space. The required air volumes result from a heat gain/heat loss evaluation of the structure. The heat gain is used to determine the required cooling for the space, while the heat loss is used to determine the required heating for the space.

The volume of air for each room in a structure varies depending on a number of factors including (but not limited to) room size, fenestration (windows, etc), direction of fenestration, insulation, panel costruction and air leakage, infiltration, exhaust and ventilation.

The size of the ducts that are used are determined by the amount of air that they are required to carry to a specific area in the structure. For example, a home may require 1,400 cfm air for cooling so the duct that is connected directly to the aoir handler must be sized to carry 1,400 cfm of air. A small room at the end of the house may only require 200 cfm, so the duct for that room will be much smaller. The number of supply registers is determined by the individuals designing the system and can vary, as long as the required air volume is delivered.

Keep in mind that the cfm requirment for any given area will be different for heating and cooling and the ductwork for each room must be sized to carry the larger of the heating or cooling air volume.

Amy

Air Duct Requirements

What is the requirement on air ducts. Is it a certain number of vents per square feet? I'd appreciate anyone's input on this (either the code or where I can find the info). Thanks!