How big of a return does a 4 ton unit need?
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.
What size should the return air grill be for a 4 ton AC 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 size should my return air duct be?
A typical supply vent is 4 by 10 to 12 inches and a typical return vent is 16 by 20 inches or larger. Houses often have two or more return collecting points, each with a filter, which join before re-entering the heating unit.
Can a return air duct be 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 return do I need?
Generally, if you are using a Duct Sizing Chart or calculator (such as the Trane Ductulator), size the re- turn ducts for 0.05 inches/100 ft (0.40 Pa/m) based on the expected airflow through that return air duct. The total sum of air from all the returns should be at least 250 CFM/nominal ton (33 l/s per-kW).
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. 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.
How do you size a return air grill?
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 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 do you measure a return air grill?
How to Measure and Install a Return Filter Grille – YouTube
What size return duct do I need for a 3 ton?
Electric heat pumps shall be tested in accordance with UL 559 or UL 1995. Example: 3.5 ton heat pump. The duct for this system must be sized by using 6 square inches of clear duct area for each 1000 BTU of cooling. Each ton of cooling contains 12,000 BTU.
Should supply and return ducts be the same size?
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.
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.
Do I need more return vents?
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 I have enough return air?
Try this simple test when your HVAC system is running: get a piece of tissue paper and dangle it about six inches from one of the return vents. You should be able to see it being gently pulled towards the vent. Next, place it up against return vent and see if the air suction holds it in place.
How do you increase return air flow?
5 Ways to Improve Airflow in Your Home
- Check Vents and Registers. One of the simplest things you can do to increase airflow in your home is to check the vents and registers in each room. …
- Turn on Ceiling Fans. …
- Schedule HVAC Maintenance. …
- Consider Duct Cleaning. …
- Invest in a Ventilator.
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.
How many CFM is a 4 ton unit?
How many cfm for 1 – 5 ton ac unit ?
| Cooling Capacity | CFM (Airflow) |
|---|---|
| How many CFM is a 3 ton ac unit? | 1050 – 1200 CFM |
| How many CFM is a 3.5 ton ac unit? | 1225 – 1400 CFM |
| How many CFM is a 4 ton ac unit? | 1400 – 1600 CFM |
| How many CFM is a 5 ton ac unit? | 1750 – 2000 CFM |
How many CFM is a ton of return?
The airflow is measured in cubic feet per minute (CFM). 350 to 400 CFM per ton of cooling is required for proper air conditioning system operation.
Should return air ducts be high or low?
For optimal efficiency, it’s ideal to have return registers installed. To ensure efficiency during the cooling season, your home should have high registers. High return registers draw hot air that rises to the ceiling back into the system to repeat the cooling cycle.
Should AC return have filter?
Your AC system should have a proper fitting filter on the return side. By placing a good fitting, high quality filter on the return vent, you will remove particles from the air before they can enter the AC system. A good filter will keep your air handling unit, coils, and ducts clean.
How many square feet will a 3 ton AC cool?
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 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 |
What size air conditioner do I need for a 2000 square foot home?
Step 5: Match your square footage to an HVAC size chart
| Home Sq Footage | Air Conditioner Size (tons) |
|---|---|
| 600 – 1,000 square feet | 1.5 tons |
| 1,000 – 1,500 square feet | 2 tons |
| 1,500 – 2,000 square feet | 3 tons |
| 2,000 – 2,500 square feet | 4 tons |
Does register size matter?
Unless you are severely undersizing your register, the noise is really the only issue. So a bigger register will not help cool or heat your room better. Putting the register in a better location and making sure the air is shooting out in an efficient manner and at an efficient angle is key.
What size register do I need?
To measure your register properly, remove the existing register from the floor, wall, or ceiling in which it is installed. Then, measure the length and width of the air duct opening. If the size of the duct measures 4″x10″, for example, then a 4″x10″ register is what you’ll need.
How do you make a return air box?
Furnace Return Air Plenum Fabrication – YouTube
How do I know what size flex duct I need?
Measure the length and width of the room where the flex duct will be supplying the air. Multiply the length and width together to get the square footage of the room. For example, a 10-by-10 room will be 100 square feet.
What size duct is needed for 1000 CFM?
Rectangular equivalent diameter for air flows between 100 – 50000 cfm.
| Air flow – q – (Cubic Feet per Minute, cfm) (m3/s) | Rectangular Duct Sizes (inches) (mm) x (mm) | Friction Loss (inH2O / 100 ft duct) (Pa/100m) |
|---|---|---|
| 1000 (0.45) | 10 x 14 12 x 12 | 0.15 |
| 1300 (0.59) | 12 x 14 | 0.15 |
| 1400 (0.63) | 12 x 15 | 0.15 |
| 1700 (0.77) | 10 x 22 14 x 15 | 0.14 |
How big should supply duct be?
In the case of exhaust air, ducts are normally round and the optimal diameter is based on the airflow of the fan they are attached to. With range hoods, a minimum diameter of 4” works for fans with a CFM (cubic feet per minute) rating of less than 400. For higher ratings, sizes can go all the way up to 12” in diameter.
How do you design a return air duct?
Basic Return Duct Sizing Made Simple – YouTube
Where do you put return air vents?
The best location of the return vents depends on whether the system is heating or cooling the air. If it’s cooling, the return vents should be near the ceiling, where the warm air collects, but if it’s heating, the return vents should draw cool air from the floors.
Do you need a cold air return in every room?
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.
What is the max recommended length of flexible duct?
The ASHRAE 2009 Fundamentals Handbook (page 21.7 and 21.18) reads that “for commercial systems, flexible ducts should be… no more than 5 ft in length, full stretched.” 2. This is also included in the more recent 2013 handbook, however, the limiting length recommendation was changed to 6 feet.
How many returns should be in a house?
Your Home May Not Have Sufficient Return Vents
Having a number of return vents (preferably one in every room, but also 2 or three is far better than just one) creates regular air pressure. If you have one return vent, your house is great. Maintain the doors to every room open so air can properly flow.
Why do I have two air returns?
Having two air return vents allows you to seasonally control which air is returning to the HVAC system. In older homes, this may not be an option. The theory is that in the Summer cooling season, you want to be circulating warmer air back through the HVAC system to be cooled.
Is it OK to cover a return air vent?
Keep couches, chairs and other large pieces of furniture at least 10 inches away from your cold air return vents. Avoid covering your cold air return vents with curtains, drapes or rugs. Always check your air filters and replace them when needed. Clogged air filters can also cause cold air return blockages.