Return Air Duct Size

Duct system sizes and airflow quick chart created date.

Return air duct size.

Cfm 10 x 4. Most technicians are skeptical about these numbers especially on the return air side of the system. For example if the vents are 5 by 10 inches the total cmf for the vents is 50 cmf per vent. Calculate the return duct size based on the air conditioner s size.

The following duct sizes are based on a fraction drop of 10 inches per 100 feet of lineal duct. This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Calculate the size of your ducts vents by multiplying the length by the width. Table 4 2 return air duct installation sizes.

There usually are fewer return. The veins and arteries supplying blood to the different parts of your body even out to your fingers and toes are the same size as the veins and arteries returning that blood back to your heart. Step 5 divide the cmf per vent by the total amount of cmf for your furnace. Air return intakes sizes and capacities pdf nominal size.

Larger volumes or higher static pressures should be dealt with on an individual job basis. Based on 05 inches of pressure drop per 100 ft round duct rectangular duct cfm dia. There typically are as many supply vents as there are rooms in a house. If the furnace is.

How to size an air conditioner return air duct step 1. In x in approximately capacity. 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 200 9x8 10x7 11x6 14x5 18x4 225 9x8 10x7 12x6 15x5. Decide if you ll be using round or rectangular duct.

Table 4 2 return air duct installation sizes based on 05 inches of pressure drop per 100 ft installation guide v 8 4 52. The air ducts in your house should be designed exactly like the blood vessels in your body. The air return size for a furnace return function. For instance a 2 5 ton system approximately 400 cfm per ton would require 2 14 flexible return ducts or 1 very short flexible 18 duct to move the 1000 cfm required by the 2 5 ton system.

A furnace return system must collect all the air being put out by that system. Look for the data tag on the outside of your condenser outside unit to determine the size of your air.