What Size HVAC System Do I Need?

When replacing an AC unit, many Lancaster homeowners intuitively think: "It gets so hot here, I should buy the biggest unit possible."

This is a costly mistake. An oversized unit will cool your house too quickly, causing it to shut off before it has removed the humidity. It will "short cycle" constantly, leading to wear and tear, high energy bills, and uncomfortable temperature swings.

Conversely, an undersized unit will run 24/7 on a 100-degree day and never reach your set temperature.

The "Rule of Thumb" is Wrong

You might hear that you need 1 ton of cooling for every 400-600 square feet. By that logic, a 2,000 sq. ft. home needs a 4-ton unit.

But that rule doesn't account for the Antelope Valley factor. Here, we have to consider:

• Heat Gain: Single-pane windows facing west in Palmdale absorb massive amounts of heat in the afternoon.
• Insulation: Does your attic have R-30 insulation or barely any?
• Ceiling Height: High cathedral ceilings trap heat and increase the volume of air that needs cooling.

Manual J Calculation

The only accurate way to size a system is with a "Manual J" load calculation. This is a scientific formula that HVAC professionals use to determine exactly how many BTUs your home needs based on its unique construction and orientation.

Typical Sizes in Our Area

While every home is different, here represent typical ranges we see in the Antelope Valley:

• 1,200 - 1,500 sq. ft.: Usually 3 to 3.5 Tons.
• 1,600 - 2,100 sq. ft.: Usually 4 to 5 Tons.
• 2,200+ sq. ft.: Often requires two separate units (e.g., one for upstairs, one for downstairs) or a large 5-ton system with zoning.