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To calculate return air grille size, take the CFM of the HVAC unit and divide it by 350 to get the grille area in square feet. Next, multiply the grille area by 144 to convert it into square inches. Finally, choose your preferred grille size that matches the required grille area.
What size should my air return be?
A typical return vent is 16 inches by 20 inches, according to Hunker.
What size return grill do I need for a 3 ton system?
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.
How do you size a supply grille?
Always measure the width first, followed by the height — you don’t want your louvers facing in the wrong direction! Unless you select a square grille (such as a Cube Core with an Eggcrate design), the size of the hole in the wall will not be the size of the grille you need.
How do you calculate return filter size?
Calculate the area in square inches you need for your filter grille. For proper operation, plan on 2 CFM per square inch of filter grille area. So if your furnace puts out 800 CFM, you need 400 square inches of filter grille area.
Can air return too big?
Can an air return be too big? No, an air return cannot be too big, except in extreme cases where a closed room is temporarily under negative air pressure. Return vents maintain air pressure, filter out debris, and are critical to the efficient operation of any HVAC system.
What size should the return air grill be for a 5 ton AC unit?
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.
How much return air do I need per ton?
You can never have to much return air, as a HVAC contractor you want no less than 144 square inches per ton. Regarding the 3.5 TON VS 4 TON The average square foot per Ton is 400 so say the house is 1600 SQFT a 4 TON unit should work great.
How many returns do I need for a 4 ton unit?
(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.).
What happens if there is not enough return air?
If there is not enough return air available, your HVAC system will not heat or cool properly. If not enough air is brought back, your HVAC system will not be able to keep up with temperature demands. In some cases, two returns may be necessary to provide enough return air.
How do I calculate my air filter size?
For best results, use 2.00 cubic feet per minute per square inch of filter area. Example 2: 2000 ÷ 200 inches = 1000 square inches of 40″ X 24″ filter. Usually two grills 20″ X 25″ each would be used.
Should return duct be same size as supply?
Yes, return ducts are usually larger than supply ducts to ensure that air within the home is balanced. There are generally more supply vents in the system creating the need for return vents to be larger.
Should return air vents be high or low?
It’s important to remember that hot air rises and cold air falls. In the winter you want the cold air to be drawn through the return registers leaving the hot air behind. By opening the lower registers and closing the top ones you keep hot air in and draw the cold air out.
How many square feet will a 5 ton AC cool?
How many square feet does a 1 – 5 ton air conditioner cool? AC Unit Capacity (Ton) Cooling Capacity Square Feet 3 Ton 1,400 – 1,600 sq ft 3.5 Ton 1,650 – 1,800 sq ft 4 Ton 1,850 – 2,100 sq ft 5 Ton 2,400 – 3,000 sq ft.
How many square feet does a 3 ton unit cover?
3-ton is equal to 36,000 BTU. If you apply the 20 BTU per sq ft rule of thumb, you can see that a 3-ton air conditioner cools about 1,800 square feet spaces.
How much square footage can a 4 ton AC unit cool?
ZONE 1 ZONE 4 3 Tons 1501 – 1800 sf 1601 – 2000 sf 3.5 Tons 1801 – 2100 sf 2001 – 2250 sf 4 Tons 2101 – 2400 sf 2251 – 2700 sf 5 Tons 2401 – 3000 sf 2751 – 3300 sf.
Can flex duct be used for return air?
Flex duct is widely used for return air in commercial air conditioning systems. Flex duct is able to withstand a certain negative pressure of return air. When installed properly, a flex duct is a reliable and convenient ductwork solution. Flex duct often gets a bad rep because of airflow issues.
What size ductwork do I need for a 5 ton unit?
Using this approach, two 20-in. x 25-in. return grilles will be the right choice for a five-ton HVAC system in order to actually deliver 2,000 cfm back to the blower without causing the return to hemorrhage.
Can ductwork be too big?
The Ducts Are Too Large Not much. This is what happens when your air ducts are too big for your system. Your system pushes air into the ducts, but the ducts are too large for it to build up any sustained amount of air pressure, and thus a “forced air” system doesn’t have any force.
