# Fresh air required



## Alinaseem (Jan 23, 2016)

*Hi , Everyone

i am little confused regarding the Total Fresh air fain coil unit and Mix air unit 

1) as you can see below that the 4TR unit is a total fresh air unit , providing the total of 740 CFM , but its a 4TR unit which means 4TRx400CFM = 1600 CFM , why the capacity is only 740 CFM , 

2) how do we calculate the required Fresh for a certain space ?

3) lets say i have a 5TR unit in a corridor means 2000 CFM capacity i will provide 1750 CFm to the corridor and remaining 250 to the rooms as a fresh air 50 cfm per room . so how much cfm of fresh air i have to provide from outside ??


please feed me with comments thank you so much *

http://postimg.org/image/vm6i1uy95/

Please check the picture you will understand better


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## beenthere (May 30, 2009)

Check your ASHRAE manual.


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## heatingrepairchicago (Nov 8, 2014)

beenthere said:


> Check your ASHRAE manual.


bingo! good luck


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