HVAC Load and Capacity Calculators

Calculators

• Manual J HVAC Load Calculator
  Estimate residential heating and cooling loads from envelope heat transfer, infiltration, solar gain, occupants, and internal loads.

Frequently Asked Questions

Is 400 CFM per ton always correct?

No. Actual design airflow can be lower or higher depending on sensible heat ratio, humidity control, equipment, and climate.

What does the 1.08 factor represent?

It is a common sea-level sensible heat approximation for standard air; density and altitude can change it.

Does dry-bulb temperature split show total capacity?

No. It estimates sensible capacity only and excludes latent moisture removal.

Should measured airflow come from grille velocity alone?

Use a reliable airflow measurement or validated equipment and static-pressure method.