How big should my return air grill be?

In order to determine the size of the tonnage you have, simply divide 980 by 400 CFM per ton. Doing this for this space will yield a tonnage of 2.45. Always round up and we have a tonnage value of 2.5. A return air grill should be sized for an air speed of 300-500 FPM(feet per minute).

What size should the return air grill be for a 3 ton AC unit?

A 3-ton heat pump has approximately 1200 CFM of air flow. To calculate the filter grill size, divide the airflow, (CFM), by 2. One filter grill or the total area of all grills must equal at least 600 square inches of area to adequately supply the system with the air needed to operate.

What size should the return air grill be for a 4 ton AC unit?

Calculate the square root of the total. (Example: 4 (ton unit) x 144 square inches = 576 squared. The square root of 576 is 24. Therefore, your return air duct and grill size will be 24 by 24 inches.)

How big does a return air plenum need to be?

The size of the plenum, as in any duct system, depends on the length of the plenum. In most cases, where the plenum duct length is less than 150 feet (45 m), the plenum will be 7-inch (178 mm) diameter or 8.5 x 8.5-inch (216 x 216 ,mm) square. However, in certain instances you will need to use larger duct.

What size should the return air grill be for a 5 ton AC unit?

x 25-in.
x 25-in. Return grilles are the best choice for a five-ton system in order to deliver 2,000 cfm back to the blower without causing the return to hemorrhage.

Do I need a return plenum?

Return air plenum is not required. The return plenum is a box that connects the return ducts in your ductwork back to your HVAC system. The air is then sent back into your HVAC system through a return inlet to be put through another cycle of cooling or heating.

Can HVAC have too much return air?

It isn’t possible to have too many returns.. However, the blower will move only so much air. If there is not enough return air available, your HVAC system will not heat or cool properly.

How big is a return air conditioner Grill?

(Example: 4 (ton unit) x 144 square inches = 576 squared. The square root of 576 is 24. Therefore, your return air duct and grill size will be 24 by 24 inches.)

How big of a return duct do I need for a grill?

One filter grill or the total area of all grills must equal at least 600 square inches of area to adequately supply the system with the air needed to operate. 1 ton of cooling = 12,000 BTU 1 ton of cooling = 400 CFM (approximate) Heat Pump Size (Tons) Minimum Duct Size (Square inches) Minimum Return Size (Square inches)

How to calculate required return grille airflow?

First, calculate the percent of outside air compared to system airflow by dividing the outside air CFM by the total supply airflow. Example: 200 CFM outside air divided by 2000 CFM of supply air equals 10% outside air.

What should the tonnage of a return Grill be?

Doing this for this space will yield a tonnage of 2.45. Always round up and we have a tonnage value of 2.5. A return air grill should be sized for an air speed of 300-500 FPM (feet per minute). 400 FPM is the median air speed for this calculation. We are after the ability to move 980CFM so you now divide this number by 400 FPM yielding 2.45 or 2.5.

How big do return air grills need to be?

M918.10 Return air intake (non-engineered systems). If only one central return air grill is installed, it shall be of proper size. The size shall be sufficient to return a volume of air compatible with the CFM requirements and temperature rise limitations specified by the equipment manufacturer.

How big is an average air return intake?

Size and capacity of air return intake Nominal Size (in x in) Approximately Capacity (cfm) 10 x 4 100 10 x 5 125 10 x 6 155 10 x 8 215

What do air grilles do for an AC unit?

Grilles are designed to pull air out of a room, ensuring energy efficiency and relative comfort while also providing circulation back to the central heating or air conditioning unit.