Load Calculations

What is a Load Calculation and do you need one?  I’m of the belief that everyone needs one. 

A Load Calculation determines the proper sizing for an Air Conditioner. It’s sometimes referred to as a Manual J. In a nutshell, dimensions are taken of the house, the direction it faces, the windows, the insulation, the building materials, and a few other things to determine what size AC is optimal for your home. BIGGER IS NOT ALWAYS BETTER!!!! If the AC is too big (and we see this a lot in Houston) it will not run long enough to dehumidify the air. Homeowners will typically turn the thermostat down lower just to make it run long enough to feel comfortable in the home. It’s not the temperature that makes them uncomfortable – it’s the humidity. Conversely, if the unit is too small, it will have trouble cooling on the absolute hottest days.

For any residential AC replacement, a Load Calculation should be the first step taken by the AC company. There is no magic rule for determining AC size based on square footage. There’s a “rule of thumb” but it’s also called the “rule of dumb.” Always make sure the company you hire to change out your AC performs a Load Calculation!