HVAC Airflow & BTU Load Calculator

Inputs

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Supply, return or ventilation airflow through the coil or heat exchanger.
cfm
Air temperature rise for heating or drop across a cooling coil. Use the absolute difference.
°F
Target sensible capacity used to back-calculate required airflow and ΔT.
Btu/h
Air density at the coil or duct condition. Room-temperature sea-level air is about 1.2 kg/m³.
lb/ft³
Specific heat of air. Dry air near room temperature is about 1.006 kJ/(kg·K).
kJ/kg·K

Results

Default result
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Sensible load (q)
11,440 Btu/h
Pass

sensible-only capacity from airflow and temperature difference

Also computed

Airflow for target load (Q_req) 789.8 cfm

ΔT for target load (ΔT_req) 29.82 °F

Cooling tons equivalent (tons) 0.9535 tons

Airflow per ton (CFM/ton) Caution 555.6 cfm/ton

high airflow per ton; check coil leaving-air temperature and noise

Air mass flow (ṁ) 39.68 lb/min

Method notes 3 notes
  • Sensible heat only: q = ρ · cₚ · Q · ΔT. It does not include latent/moisture load.
  • With standard air, the same relation is the common imperial shortcut q ≈ 1.08 × CFM × Δ°F.
  • Use Manual J/ASHRAE load methods, equipment data and psychrometrics for final HVAC equipment sizing.

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