What materials can be used to create cold air returns?

How do you make a cold air return?

Quote from the video:
Quote from Youtube video: So what I've done here is I've cut in an elbow. Into the existing cold air return. It comes down to this pipe here sucking air in this cavity. From the floor. So when the furnace kicks on.

Do cold air returns need to be metal?

Unlike supply vents, return vents do not need to be cased in metal. They can be placed into staircase cavities, stacked closets that run one on top of the other, or in stud cavities in the wall.

How do you make a return air box?

Quote from the video:
Quote from Youtube video: Cut size and then the height is going to be 21 and 1/2. Plus the quarter-inch that goes into Pittsburgh and and the two-inch to go in which is go in for the reinforcement. So that adds up to 23.

How big does a cold air return need to be?

16 inches by 20 inches

A typical return vent is 16 inches by 20 inches, according to Hunker. It includes the cold return air duct grille. If you consult the duct CFM sizing chart, you can quickly figure out that a 16×20 inch can handle about 1,500 CFM airflow.

Can flexible 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 cold air returns need filters?

In general, it is recommended to have an air filter in every return vent (as long as you choose the one of the right size and thickness). The filters will improve the air quality in your house and will protect the HVAC equipment from dust, pollen, pet dander, and hair.

Can wood be used for ductwork?

Wood should never be used for duct work and by altering the original design which was probably adequate, they may have introduced other problems and there should be an evaluation (manual D) done to confirm that proper airflow is achieved.

Should cold air returns be high or low?

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.

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.

Can you have too much cold air return?

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.

Can a return duct be too big?

No such thing as too much return. It will not take in any more air than it pushes out, thus no such thing as too big. Its hard to imagine a return that is too big ,but you want the return to have some draw to evacuate an area.

How long can a return air duct be?

Duct Size – Single Return



For most systems, the minimum duct size (see Table 1) is sufficient for up to 25 feet (8 m) with no more than three 90° bends.

What size return duct do I need for a 3 ton?

Recommended airflow is typically 400 cfm per ton of AC. A 3 ton AC would therefore need 1200 cfm airflow. With only 423 sq in of return your air velocity through the grille would be just over 400 ft/min, a good number as far as noise is concerned.

Should return duct be larger than 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. Ensuring that there is sufficient air supplied and returned is critical to maintaining an ambient environment.

How much return air do I need for a 4 ton?

(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 duct do I need for a 12×12 room?

A 12×12 foot room will need a 4×8 inch supply duct to get an adequate CFM rate, which is about 144 CFM. However, these figures are just “rule of thumb” measurements and will differ based on various factors of your home and HVAC system.

How many square feet will a 3 ton AC cool?

about 1,800 square feet

How many square feet does a 3-ton air conditioner cover is quite easy to answer as well. 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 CFM does a 14 flex duct carry?

CFM Sizing Chart For Flex Round Ducts (50-1,700 CFM)

What happens if ductwork is undersized?

Ducts that are undersized will increase the static pressure, which will result in excessive noise as air moves through the system. It is often loud enough to be distracting, so it will not be difficult to overlook and should be addressed, as undersized ducts overwork the heating unit.

What size duct do I need for 2000 CFM?

Rectangular equivalent diameter for air flows between 100 – 50000 cfm.