HVAC Zoning Bypass Temperature Calculator

Operating Mode
Select the operating mode you want to model.
Enter the total airflow moving through the heating or cooling equipment.
Measure the air temperature at the return grille before bypass air mixes with it.
In heating mode, enter the measured temperature rise. In cooling mode, enter the measured sensible dry-bulb temperature drop as a positive number.

Select a mode and enter all three values to calculate Pass 1, Pass 2, and theoretical steady-state temperatures.

How to interpret the results: A pass represents one complete recirculation, mixing, and conditioning cycle, not a specific number of minutes. Cooling projections assume the equipment maintains the entered sensible dry-bulb temperature drop. Actual temperatures may differ as airflow, entering wet-bulb temperature, latent load, refrigerant operation, staging, and outdoor conditions change. Compare results with equipment ratings and manufacturer instructions.

Results assume constant airflow and temperature change, complete mixing, and no heat gain or loss through the bypass duct.
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