Return Air Grille Size For 5 Ton Unit
(in multilevel homes, a central return should be installed on each. So you need 2000 cubic feet of air per minute coming back to the air handler.
The size of the return air grill depends on the size of the forced air fan.
Return air grille size for 5 ton unit. 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. Op, i recommend a 24'x24' grille/filter assembly. 340 cfm of return air x 87.5% = 298 cfm.
If your ductwork is slightly smaller than the diffuser size, you would have to open up another wall pocket, put a crosspiece at the top of the opening, cut out the bottom plate and connect it to the existing duct. As r mentioned 1 ton = 400 cfm's. This pulls the air across your body.
If only one central return air grill is installed, it shall be of proper size. 400 fpm is the median air speed for this calculation. What size is your ac unit, if its 4 ton, you would need two of these.
It’s a 1600 cfm system with 200 cfm of outside air (200/1600 = 12.5% of outside air). Calculating return grill size is really a velocity issue because. 89p75 | model/part # :
You have a 3 ton unit which is 1200 cfm's. 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.the vacuum pump pull 2500 micron is not as important as did it hold at 2500. “for the same 2.5 ton system with a filter grille, the grille size would need to be what size?” asked rick “we usually use a 20 x 20 for 2.5 ton.” said the tech 20 x 20 x 2 = 800 “800 cfm…well that’s big enough for a 2 ton, but a 20 x 25 may be a better choice.
I am trying to improve air flow for a 5 ton horizontal unit located in the attic. The square root of 576 is 24. Situations may arise where you want or need to install the filter at the return air grille.
A) the slower the air is moving the better the filter can grab crap out of the air. Specify a method for determining the size of the transfer grille or door undercut. Return air should be sized at 200 square inches per ton according to airmate and other filter grille manufacturers to achieve 2.0 static pressure.
4 (ton unit) x 144 square inches = 576 squared. A filter grill should be sized for a maximum face velocity of 300 fpm. This comes in handy if your furnace is in an attic or otherwise hard to access area.
Therefore, your return air duct and grill size will be 24 by 24 inches.) Not the total external frame size of the grille or register. The present return grille is a 20x36 which i now understand is an odd size and i should use a 24x30 (the same 720 sq ins).
When properly maintained, they are also the easiest way to save money with your air conditioning unit. A return draws air into a return duct system with negative pressure compared to the space usually via a fixed “grille” but 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”. You need about 400 cfm per ton.
B) air moving too fast will be noisy. Click here to view replacements. Recommended airflow is typically 400 cfm per ton of ac.
Calculate the square root of the total. We are after the ability to move 980cfm so you now divide this number by 400 fpm yielding 2.45 or 2.5. The most common place you will find furnace filters are either in the unit or in the return air ductwork right next to the unit.
You can never have to much return air, as a hvac contractor you want no less than 144 square inches per ton. The return air duct should have an unobstructed 6. It should be right at the unit return opening and if you have room use a deep pleated filter (accordian shaped), not a flat.
A 14 round pipe is equivalent to 750 cfm's. You need to measure you main return trunk. A mismatch in return air inlet grille or duct size will reduce the system's effectiveness.
Reduce your energy costs with the right air conditioner filters & return air grills. A 3 ton ac would therefore need 1200 cfm airflow. What size is the return air duct, at the furnace or airhandler?
Was the 3.5 ton unit a replacement for a smaller capacity unit ? For example, a 5 ton unit. You may round this number off to 300 cfm.
Note also the return air grille sizing formula at the top of the chart. If it's flex it's 700. Also, where is the return air filter, in the unit or in the return grille ?
If my math is correct, when i use round flex duct, i should use 24? Specifically, it says the following: If the supply ducts are in the floor, then the return air should be located up high.
Your air conditioning filter and return air grill do more than just prevent particulates and odors from being recirculated. If that 14 round return is all you have it is undersized for your unit. A rough rule of thumb is to take the dimesions of the truck and times it by 6.
It has to be big enough to handle all the air coming from the return air registers. You determine a return grille pressure zone required 340 cfm of return. 18.5 x 17.75] 4.7 out of 5 stars 151 $34.73 $ 34.
The distance from the return grille, in the ceiling, to the evap coil opening of 22x26, is approx 10 ft. That would further exacerbate the whistling problem. The return air vent openings need to be on the opposite side of the room so the conditioned air is pulled across the room.
The return air grid to reduce noise should be 5 to 8 times the size of the fan outlet.
