How big should the return air grill be?

The actual return grill size is not covered by the NC Mechanical Code but, the generally accepted formula for determining the filter grill size is 1 square inch of grill area for each 2 CFM3 of air flow. If the actual airflow is unknown, use 400 CFM for each ton of cooling.

How do you size a return air grille?

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.

Can a return air grille be too big?

Return ducts and vents cannot be too big. A big grille won’t help if the duct is small.

How big should my return air duct be?

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 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.

Can you have too much return air?

This isn’t the most efficient system. 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 much return air do I need?

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.

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 happens when you dont have enough return air?

A symptom of not enough air from return vents is a difference in pressure between your rooms. Rooms closer to the HVAC unit will get more return air than rooms further from the HVAC unit. As a result, you will have different air pressure in different rooms.

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 many CFM can a 5 duct handle?

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

What size return does a 5 ton unit need?

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 square feet does a 3 ton unit cover?

Generally, a 3-ton air conditioner can comfortably cool a 1500 square feet room. For an entire house, a 3-ton air conditioner is usually sufficient for a 2000 sqft insulated house. On the upper limit, a 3-ton air conditioner can cool a house with a floor area up to 2400 sqft.

Should cold air returns be open or closed in the winter?

Because hot air rises and cold air falls, you need to adjust your return vents with the seasons. In the summer, your lower vents should be closed and your upper vents should be open. In the winter, your upper vents should be closed and your lower vents should be open.

Can you put a couch in front of a cold air return?

Home Inspection Insider explains that an air return vent needs 6-12 inches of space in front of it, and recommends that you do not put large, bulky furniture like couches and bookshelves in front of an air return vent.

Should return air 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.

Where do you put return air grille?

Ducts for returning air are located at floor level or in the walls depending on the design of the system. These require to be covered by a grill that will ensure that duct is protected. It is considered very necessary to use filters over such grills, which in turn can lead to higher efficiency in cooling or heating.

Is my return vent too small?

If the return duct is too small, there are an inadequate number of return grilles or they are undersized, it can’t return enough air to recirculate back into the system. The average duct system has 25% less return air than required according to National Comfort Institute.

What direction should the return air grilles face?

Quote from Youtube video: On the back side if you paint it black it's also going to hide it which kind of gives it the stark look in this video. This is the cold air return and the bedroom I just painted. Obviously.

How many return vents should a house have?

Ideally, every room except the kitchen and bath should have its own return air grille. At the very least, each level of the house should have one. Even so, many homes were built with just one or even no return ducts in an attempt to cut costs.

How do you measure a cold air return grill?

Quote from the video:
Quote from Youtube video: Always measure the width first followed by the height to make sure you buy the correct grill.