How big should my cold air return be?

There typically are as many supply vents as there are rooms in a house. There usually are fewer return vents, but they are much larger. A typical supply vent is 4 by 10 to 12 inches and a typical return vent is 16 by 20 inches or larger.

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.)

One may also ask, does every room need a cold air return? DEAR TIM: Ideally you want to have cold air return registers in every room. If you can’t easily install a true cold air duct back to the furnace from each room, you can sometimes fake it. You can install a cold air return register above the door from each room that connects to the hallway.

Additionally, can you have too much cold air return?

While there is no such thing as too much return air for the equipment (actually, there is, and it causes fan cavitation, but very rare), this CAN be an issue for the house. It has the potential to throw off pressures in different areas of the house.

How do you increase return air flow?

3 Simple Ways to Improve Your Furnace’s Airflow for More Comfort

  1. Unblock and clean your vents. Here’s a super easy way to increase air flow.
  2. Change your filters and clean your return grill. A dirty air filter impedes air movement and makes it hard for your furnace to work efficiently.
  3. Seal leaky ductwork. Snap on some goggles and a dust mask, it’s time to check out your air ducts.

Where should the return vent be located?

Place your cold air return vents on the inside walls of buildings at the lowest point. The return vent pulls cold air from the bottom of the room and returns it to the furnace to be reheated and returned as warm air. Unlike supply vents, return vents do not need to be cased in metal.

Should you put filters in your return vents?

Do not put filters in your supply vents. 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.

Should there be a filter in the air return?

The Case for a Return Duct Filter Regular maintenance is certainly recommended, but adding a return air filter can help to block some of this incoming debris and ensure that the air coming in is clean. Clean air means a clean system.

Can you block a return air vent?

Very similar to blocking a heat register, blocking an air return vent restricts the air flow in your home. Blocking air return vents causes your system to work harder, as there is less air flow to move the air back to the furnace.

How do you size a plenum box?

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.

Can a furnace have too much return air?

You really cannot have too much return air. Too little return air is a problem, but not too much. If you restrict the return air, it could cause problems with short-cycling of the furnace.

Do bedrooms need return air?

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.

Should cold air returns 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.

Can you use flex duct return air?

Re: Flex Duct on Return Air Diffusers – Yes or No? Flex duct effectively creates a tight radius elbow where it turns into the top of a diffuser. The high pressure loss is further increased because the flex fabric gathers at the inside of the throat and reduces the effective diameter.

How many CFM is a ton of return?

Air quantities (cfm): 400 cfm per ton of cooling is needed for normal comfort applications, 500 cfm per ton of cooling for heat pump and high sensible heat applications, and 350 cfm per ton of cooling for high latent heat applications.