Mixed Air Temperature Calculator

Your details

Choose which quantity to solve for; the others become known inputs.
Dry-bulb temperature of stream 1, typically outside air.
°F
Volumetric flow rate of stream 1.
CFM
Dry-bulb temperature of stream 2, typically return/recirculated air.
°F
Volumetric flow rate of stream 2.
CFM
Mixed air temperature
79

Resulting dry-bulb temperature after mixing

Temperature unit°F
Total flow rate10,000
Flow unitCFM
Stream 1 fraction0.2%
Stream 2 fraction0.8%
Temperature difference (streams 1 and 2)20
Stream 1 (outdoor)0.2%
Stream 2 (return)0.8%
Stream 3-

Mixed air temperature is 79.0°F.

  • Stream 1 contributes 20.0% of total flow; stream 2 contributes 80.0%.
  • There is a 20.0°F difference between streams; sizing the coil to handle the mixed condition is important.
  • Total air volume through the mixing plenum is 10000 CFM.
  • This calculation assumes adiabatic mixing (no heat gain or loss to surroundings) and uniform stream densities - adequate for standard HVAC design at typical pressure differences.

Next stepFor precise psychrometric analysis at extreme humidities or altitudes, supplement this result with an enthalpy and humidity-ratio balance using your local design-day conditions.

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