Free Mixed Air Calculator
Calculate mixed air temperature, humidity, and other HVAC system conditions and air handling units.
Air Stream Parameters
| Stream | Temp (°F) | Humidity (%) | Flow (CFM) | |
|---|---|---|---|---|
| Outside Air | ||||
| Return Air |
Calculation Options
Mixed Air Results
Your mixed air calculation results will appear here
Detailed Breakdown
Detailed calculation breakdown will appear here
HVAC System Tips
Optimal Mixing
Effective mixing of air enhances system efficiency and maintains the temperature and humidity level the same throughout the area.
Humidity Control
Ideal humidity (30-60%) increases comfort and prevents mold growth and static electricity.
Energy Efficiency
Variation of outside air ratios can conserve significant amounts of energy without compromising interior air quality.
In heating, ventilation, and air conditioning applications, precise measurement of mixed air stream properties is important for comfort, energy efficiency, and system performance. A Mixed Air Calculator is a device used by engineers and technicians to determine the resulting temperature, humidity, or other properties when two or more air streams are blended.
It defines the need for mixed air calculations, how a mixed air calculator works, and its application in HVAC design and operation.
Why Mixed Air Calculations Are Important
When outside air (OA) and return air (RA) are combined in an HVAC system, the conditions of the air being mixed determine:
- Energy Consumption – Optimal heating/cooling loads are achieved with good mixing.
- Indoor Air Quality (IAQ) – Good ventilation is accompanied by the right mixture of fresh and re-circulated air.
- System Efficiency – Inefficient mixing will lead to excessive energy usage or equipment overload.
A Mixed Air Calculator simplifies such calculations to deliver efficient and accurate system performance.
How a Mixed Air Calculator Works
The calculator uses the Formula for Mixing of Two Air Streams:
Tmix=(((T1*CFM1)+(T2*CFM2))/(CFM1+CFM2))
Where:
- Tmix = Mixed air temperature (°F or °C)
- T1,T2T1,T2 = The two air streams’ temperatures
- CFM1,CFM2CFM1,CFM2 = Airflow rates in Cubic Feet per Minute
For combining humidity, the same weighted average method is used to moisture content (e.g., grains of moisture, or specific humidity).
Example Calculation
Suppose:
- Outside Air (OA): 90°F at 500 CFM
- Return Air (RA): 75°F at 1000 CFM
Tmix=(90×500)+(75×1000)/500+1000=45,000+75,000/1,500=80°F
The mixed air temperature is 80°F.
Applications of a Mixed Air Calculator
- Air Handling Unit (AHU) Design – Helps in determining the appropriate mix of outside air and return air to provide optimum performance.
- Energy Recovery Ventilation (ERV) Systems – Allows easy heat transfer from incoming air to exhaust air.
- Economizer Operation – Controls when to introduce additional outside air for “free cooling.”
- Humidity Control – Controls moisture content in mixed air for comfort and mold control.
Benefits of Using a Mixed Air Calculator
✅ Saves Time – Manually calculating would take time; automation speeds it up.
✅ Improves Accuracy – Reduces human error in critical HVAC choices.
✅ Increases System Efficiency – Provides maximum air mixing for energy efficiency.
✅ Helps with Compliance – Helps meet ventilation standards like ASHRAE 62.1.
Conclusion
A Mixed Air Calculator is a convenient tool of Calculator Pro Tool for HVAC engineers to aid in efficient and accurate air mixing for the best system performance. Through the use of this tool, engineers are able to design better ventilation systems, reduce energy costs, and provide better indoor air quality. Whether you are a student, an engineer, or an HVAC technician, learning and applying a mixed air calculator can actually enhance your workflow and system outcomes significantly.