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Discussion Starter #1
How much Return air is needed for a 5 ton system with the blower set on 2000cfm .. I currently have a 20x30 return air grill and I don't think that is big enough?
 

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a 20x30 return will pull 5500 cfm. you need to have 2000 cfm. you need to check duct size tho, not just opening. need minimum 20x14 or 18inch round
 

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is there a filter in this return grill ? What is your main return line duct size?

Assuming there is, your way undersized.

You have enough return for a 2.5 ton system.

20x30 is good up to 1074 CFM

You would probably benifit from adding another 20x30 somewhere in the house.

Does your return air grill sound like an industrial vacuum cleaner?


Here is a helpful document:

http://www.google.com/url?sa=t&source=web&cd=1&sqi=2&ved=0CBYQFjAA&url=http%3A%2F%2Fefficientcomfort.net%2FRules_and_Rules_of_Thumb_for_Duct_Systems.pdf&rct=j&q=rules%20of%20thumb%20for%20duct&ei=62XyTd2VNc23tgfJ-IiiAw&usg=AFQjCNF9kxVPmB9xLvZpx2-lISZXDgXEQQ&cad=rja
 

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Discussion Starter #4 (Edited)
Yes there is a filter in this grill .. The duct inside the chaise that goes up in to the attic is 27.5" width and 19.5" depth..

Guess I could add another return grill with flex and run it to the return in the attic..


d
is there a filter in this return grill ? What is your main return line duct size?

Assuming there is, your way undersized.

You have enough return for a 2.5 ton system.

20x30 is good up to 1074 CFM

You would probably benifit from adding another 20x30 somewhere in the house.

Does your return air grill sound like an industrial vacuum cleaner?


Here is a helpful document:

http://www.google.com/url?sa=t&source=web&cd=1&sqi=2&ved=0CBYQFjAA&url=http%3A%2F%2Fefficientcomfort.net%2FRules_and_Rules_of_Thumb_for_Duct_Systems.pdf&rct=j&q=rules%20of%20thumb%20for%20duct&ei=62XyTd2VNc23tgfJ-IiiAw&usg=AFQjCNF9kxVPmB9xLvZpx2-lISZXDgXEQQ&cad=rja
 

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Discussion Starter #5
Is it ok to add another return above the other return in the hallway or should it be somewhere else.. Anybody know of any sites that show you more about adding the return in the ceiling?
 

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