CFM Chart for HORIZONTAL Return Air Grilles
| Grille Area (sq.in) | Grille Size (in) | Airflow (cfm) |
| 24 | 4 x 6 | 58 |
| 48 | 4 x 12 | 117 |
| 60 | 6 x 10 | 146 |
| 180 | 6 x 30 | 438 |
What size return air grill do I Need?
A return air grill should be sized for an air speed of 300-500 FPM (feet per minute). 400 FPM is the median air speed for this calculation. We are after the ability to move 980CFM so you now divide this number by 400 FPM yielding 2.45 or 2.5.
How big of a grill do I Need?
Those who want to be able to cook for a larger crowd might increase to around 400 square inches. BBQ grills that are ideal for hot dogs and hamburgers go all the way up to more than 1,200 square inches in size.
What size should I order for my floor register or grill?
For all floor registers and return grilles we list the smaller size first and the larger size second. Again, this is just a matter of convention and is not critical in ordering. If you are still not sure as to what size to order please call us! We are more than happy to assist you in your selection!
What is the difference between supply side and return air grill?
A return air grill will also look similar to the supply side grill and can only be differentiated by the flow of the air. Keep the areas near and around the return air and supply side vents clear of furniture, boxes, and other items to ensure adequate air flow.
How do you know what size grill to get?
The primary factor in determining grill size is cooking area. Cooking area is expressed in terms of square inches. A typical three burner gas grill features 450-500 square inches of cooking area, which is generally sufficient for the average household.
What size return grill do I need for a 3 ton system?
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.
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.
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 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 air return do I need for a 3 ton unit?
approximately 1200 CFMIf the actual airflow is unknown, use 400 CFM for each ton of cooling. A 3-ton heat pump has approximately 1200 CFM of air flow.
How big of an air return do I need?
Method 2: Simple Rule Of Thumb Calculation If you have a house with 7 rooms, you need 7 cold air return vents. If you have a house with 12 rooms, you need 12 return vents. Example: How strong should air come out of vents for a 200 sq ft room? It should be somewhere around 200 CFM.
How do you measure a return grill?
0:221:25How to Measure and Install a Return Filter Grille - YouTubeYouTubeStart of suggested clipEnd of suggested clipReturn filter grill dimensions are based on the size of the wall or ceiling opening that should beMoreReturn filter grill dimensions are based on the size of the wall or ceiling opening that should be the same as your filter. Size.
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.
What size return 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 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 many CFM can a 5 duct handle?
50 CFMCFM Sizing Chart For Metal Round Ducts (50-2,000 CFM)Duct Size (Inches)Metal Duct Airflow (CFM)5 inches50 CFM6 inches85 CFM7 inches125 CFM8 inches180 CFM7 more rows
What direction do you run a grille in?
You may order a horizontal grille (blades run in the long direction) or a vertical grille (blades run in the short direction). You must order by the duct opening size WIDTH X HEIGHT. This is critical if the grille is on the wall.
How are air registers and grilles ordered?
Air registers & grilles are ordered by the size of the actual duct opening in the wall, floor or ceiling that the vent will fit into or cover, not the overall size of the existing vent cover!
What is a filter grille?
a grille through which the air is taken back from the room and into the return duct (it is sucked back into the wall). This may be a flat cover which is non-operable, or it may be a filter grille in which case it will have a hinged face that will open or swing down so that a filter can be put into the back filter rack.
Is it important to order a supply register for a ceiling?
If you are ordering a supply register for either the wall, floor or ceiling, the direction that you order it in is not important.
Step 1
Open up the cabinet of your furnace to gain access to the service plate. Look on the plate to see how many BTU, or British Thermal Units, your furnace puts out.
Step 2
Divide the BTU by 50 to see how much CFM, or cubic feet per minute, your furnace blows. For example, if your furnace is 40,000 BTU, it would put out 800 CFM.
Step 3
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.
Step 4
Multiply the lengths and widths of common filter grille sizes to calculate the square inches of each. Once you find one that meets or exceeds the above calculated needed number, you can use it as your filter grille size. Some of the common sizes include 20-by-14, 25-by-16 and 20-by-20.
What is a grille?
A grille is a fixed vent type that contains no damper or adjustable louvers. Grilles can be used for supply but are most commonly used in return applications. The grille shown above is a steel-stamped return grille.
What is a return vent?
A return draws air into a return duct system with negative pressure compared to the space, usually via a fixed “grille” (also often called a “return vent” or a “return intake vent,” or for some of you old-school folks from up north, the “cold air return”).
How to Calculate Return Air Grille Size
Airflow (cfm) Face Velocity (fpm) Grille Free Area (percent) x 144 = Grille Area (sq.in)
What Happens If A Smaller Return Air Grille Is Used
Using a smaller return air grille with the same type of grille will result in a greater face velocity (thus, same free area). The grille may make audible noise with a greater face velocity. The more the noise, the smaller the grille.
How to Size Return Filter Grilles
Because furnace filters should be replaced at least every 90 days, going into an attic to change the filter may be impractical. The return air filter grille must be properly sized for the furnace to perform properly.
Conclusion
Furnace filters are most commonly found in the unit or in the return air ducting or adjacent to the unit. There may be occasions when you want or need to put the filter at the return air grille. This is useful if your furnace is in an attic or other difficult-to-reach location.
What are the factors to consider when choosing a grill size?
Other Considerations When Choosing Grill Size. While burners and the grilling area are a crucial factor for cooking, there are a few other factors to keep in mind when deciding on how big of a grill do I need. How the burners line up, as well as heat diffusion and lid design, will also affect how things cook.
How much space do you need for a grill?
We’ll get more into the details of choosing sizes, but start with this easy calculation: For every person you want to cook for, allow around 72 square inches of grilling space.
What happens if the lid on a grill doesn't close?
If the lid on the grill doesn’t create a good seal, heat will escape from the grill while you are cooking.
How big is a grill?
Those who want to be able to cook for a larger crowd might increase to around 400 square inches. BBQ grills that are ideal for hot dogs and hamburgers go all the way up to more than 1,200 square inches in size. However, most households will be happy with a grill between 400 and 550 square inches in size.
What type of burners do I need for a grill?
Grill burners may be aluminum burners, cast-iron burners, stainless-steel burners, or brass burners. There are also infrared and sear burners, which are specialty burner types.
What does it mean to have more burners on a grill?
The more burners that a grill has, the more versatility you can get out of it. Of course, having more burners means that you also have to get used to working them; there is a learning curve to grilling . With three and four burners, you will be able to create low, medium, and hot zones.
Why do grills have a heat diffuser?
Grills will also have some type of heat diffuser over the burners, which allows for heat to distribute evenly. In some cases, this is a metal heat diffuser that also protects the burners from drips.
Breaking Down The Cooking Surface
When you begin looking for and researching grills, you will find information about their cooking surfaces. This is helpful but that information may be subjective.
Indirect Cooking
Another thing to note is that some cooking methods will impact the cooking space.
Avoid Crowding The Grill
Whether you go with a small or large grill, you need to use the space as efficiently as possible.
Maximize Use
If you’re going to get a bigger grill with more space, you’ll need to ensure that you can maximize that space. The best way to do that is by choosing a grill with multiple burners and controls. This will allow you to increase the temperature in one area while minimizing the temperature in another area.
How Many Guests Will You Serve
One of the biggest factors that determine a grill size is the number of guests. Basically, this means the number of people you plan on serving in a single day of grilling out.
Your Budget
Your budget will also determine the grill size. How is this possible? Well, as you may have already found out, the larger the grill, the higher its price tag.
Your Location
Another important factor that determines a grill size is the consumer’s location. What does this mean in this case? Well, it means that consumers who live in small spaces, such as apartments, condos, and flats, will have to settle for smaller grills. This is especially true for those who have limited outdoor space.
