Mixed Air Formula Example 3
Formula to use if you know Outdoor Air Temp, Outside Air Requirement, return air temperature, and Return Air Percent required. Mixed Air Temperature, expressed as a function of return air temperature and percentage, and outside air temperature and percentage:
Mixed Air Temp= {{(RAT x RA%) + (OAT x OA%)} / 100} x 100
For Example:
Outside Air intake = 20%
Outside Air temp = 90°F
Return Air Temp = 70°F
Return Air intake = 80%
Step 1: Mixed Air Temp={{(70° F x .8%)+ (90°F x .2%)} / 100} x 100
Step 2: Mixed Air Temp={{ 56 +18 }/100} x 100
Step 3: Mixed Air Temp={74/100} x 100
Step 4: Mixed Air Temp= .74 x 100
Step 5: Mixed Air Temp= 74°F