How big should my AC return be?

How big should my AC return be?

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. Convert this measurement to inches.

How much return air do I need per ton?

Since the conventional wisdom of designing return grilles at 144 sq.in. per ton is so widely accepted, the average system return is undersized by 30% or more.

How do I calculate my HVAC return?

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.)

Can you have too much return air?

It isn’t possible to have too many returns.. However, the blower will move only so much air. They must be properly sized — Return air ducts must be large enough to carry a sufficient amount of expended air back to your furnace, air conditioner, or heat pump.

Should return duct be larger than supply?

The return vents in your home suck the air from your rooms into your return ducts and back to your heating and cooling system. Your return vents are typically larger than supply vents, and you will not feel air being blown out of them.

How many CFM is a ton of return?

3. Supply air and return air is always equal because its a closed loop system to the equipment. 1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on.

How many CFM is a 2.5 ton unit?

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.

Does every room need a cold air return?

Having several return vents (ideally one in every room, but even two or three is better than just one) creates consistent air pressure. If you have one return vent, your home is fine. Keep the doors to each room open so air can properly circulate.

How do I know if my return air is working?

You can identify return vents by turning on the system fan and holding your hand or a piece of paper up. If the paper is pulled toward the vent or you feel a suction effect, it’s a return vent.

Do all rooms need a return air vent?

Does Every Room Need Air Return Grilles? While it is a myth that air return grilles are required in each and every room in the house, it is definitely necessary to have more than one of these grilles installed at strategic places in the house. The most important place to have these would be the bedroom.

How much return do I need for a 4 ton ac unit?

1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on. So a 4 ton unit will have 1600 cubic feet of air passing through the system every minute. Can you have too much return air?

How many CFM is a 4 ton ac unit?

Supply air and return air is always equal because its a closed loop system to the equipment. Similarly one may ask, how many CFM is a 4 ton unit? 1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on. So a 4 ton unit will have 1600 cubic feet of air passing through the system every minute.

How big is an air conditioner return duct?

For rectangular duct: Size of air conditioner (example: 4 tons) x 144 square inches = return air duct in square inches. For round duct: Diameter of duct x 3.14 = return air duct in square inches.

How much air conditioner tonnage per square foot?

According to the DOE, “…an air conditioner generally needs 20 BTU for each square foot of living space.” We need to convert BTU to tonnage. 1 ton equals 12,000 BTU. That means that, on average, we will need 0.0016 tons per square foot.

How to calculate the tonnage of an AC unit?

AC Capacity = 600 sq ft * 0.0016 tons/sq ft = 1 Ton In general, for every 600 sq ft, you need 1 ton of AC. This is a general estimate. You can use the ‘tonnage per square foot’ formula to calculate how many tons of AC you need.

For rectangular duct: Size of air conditioner (example: 4 tons) x 144 square inches = return air duct in square inches. For round duct: Diameter of duct x 3.14 = return air duct in square inches.

How many square feet does a 4 ton ac unit cool?

Hello Isa, 4 ton (48,000 BTU) unit should be theoretically enough to cool down spaces up to 2,400 sq ft. In practice, the Energy Star guide recommends that you add 600 BTU per person. Let’s say you have 17 people in the shop, that would be 17*600 BTU = 10,200 BTU.

How big of an AC unit do I need for 1, 500 sq ft?

To properly get the tonnage of the AC you need, you can use the AC tonnage calculator here: For example, a standard 1,500 sq ft house would need a 2.5-ton air conditioner. To help us out, here is a quick table showing how many tons (and BTU) air conditioners we need for certain square footage: