Why Does AC Direct Charge for Its Sizing Software?

Free for customers, built on Manual J

The sizing software on the AC Direct site is free for our customers. It is built on Manual J, the standard residential load calculation method the HVAC industry recognizes. Many free calculators on other sites use square footage as their main input. They may ask for extra details, but their results are far less reliable than a true Manual J calculation. Your local licensed contractor or permitting office can confirm the load calculation your project requires.

Why square-footage tools fall short

A simple calculator treats every home the same. It cannot account for the things that change real cooling and heating loads, such as insulation values, climate type, window area, and construction quality. Try a few free online calculators and you will see them return conflicting numbers, because no standardized criteria sit behind them.

What proper sizing factors in

Why correct capacity matters

Capacity is one of the most important decisions you will make when choosing a home comfort system. A system that is too large or too small limits your comfort, raises energy costs, and shortens equipment life. We also offer a quick free estimator, though like other basic tools it is not comprehensive enough for homes with very different insulation, climate, or construction. For a true result, use the Manual J based program, and have a local licensed contractor confirm the final sizing before installation.