Standard Air Conditioning Duct Sizes

You can obtain these from ductwork manufacturers or from industry bodies such as cibse and ashrae.

Standard air conditioning duct sizes.

Ventilation systems for ventilation and air handling air change rates ducts and pressure drops charts and diagrams and more. Size of air conditioner example. So if you have a two ton system you need ductwork that will carry 800 cfm. The square root of 576 is 24.

Duct sizing how to size ductwork. Optimal airflow based on cubic feet per minute as well as velocity of air provided by other components of the hvac system determine the correct ductwork sizing for each scenario. Step 4 calculate the square root of the total. Larger volumes or higher static pressures should be dealt with on an individual job basis.

This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Link 1 and link 2. But your hvac dealer only has air conditioners that handle 24 000 or 30 000 btus. Hvac systems heating ventilation and air conditioning systems design and dimensions.

4 ton unit x 144 square inches 576 squared. To size the ducts you re going to need a duct sizing chart. Ordinary heating ventilating and air conditioning duct systems read air pressures at 0 4 psi or less often much less. These charts hold a lot of information.

Air duct components and minor dynamic loss coefficients minor loss pressure or head loss coefficients for air duct distribution. For example the manual j calculation may say you need 25 000 btus for cooling. One six inch round duct is good for about 120 cfm a six inch duct carries about 150 cfm and eight inch carries about 200 cfm of cool air. Rectangular rectangular or square ducting comes in standard sizes ranging from 3 by 7 inches to 35 by 40 inches.

1 psi equals 27 7 inches of water gauge. Also you want to make sure that the return ducts are the same size as the supply ducts. If your btu requirement is between sizes simply go with the bigger unit. Sometimes the dealer may not have your exact btu size but don t worry.

A common duct pressure of 0 25 inches water column is equal to 0 25 divided by 27 7 in wc psi 0 009 psi. The following duct sizes are based on a fraction drop of 10 inches per 100 feet of lineal duct. 4 tons x 144 square inches return air duct in square inches. Duct system is pressurized by three pressures.