What Size AC Do I Need for My San Antonio Home?
When you replace an AC, the size of the new system matters as much as the brand. Too small and it cannot keep up in a San Antonio summer. Too big and it short-cycles and leaves the house clammy. Here is how sizing works.
Tons and BTUs, in plain words
AC size is measured in tons. One ton of cooling equals 12,000 BTUs per hour. It has nothing to do with weight. Most homes use systems somewhere between about 1.5 and 5 tons. A 3-ton system, for example, moves 36,000 BTUs of heat out of the house each hour.
Why square footage alone is not enough
You will see charts online that match square feet to tons. They are a rough starting point only. Two homes with the same square footage can need very different systems because of:
- Insulation in the attic and walls
- Windows: how many, which way they face, and how much afternoon sun they get
- Ductwork in a hot attic, and how well it is sealed
- Ceiling height, shade trees, and the number of people living there
The problem with an oversized AC
Bigger is not better. An oversized system cools the air fast and shuts off before it has removed much humidity. In humid San Antonio weather that leaves the house cool but clammy. It also turns on and off more often, which wears out parts sooner.
The problem with an undersized AC
A system that is too small runs nonstop on hot afternoons and still may not hold your setting. Some of that is normal on extreme days (see the 20-degree rule), but a system that never catches up in normal summer weather may be undersized.
How the right size is chosen
The right way to size an AC is a load calculation (called Manual J in the trade). It uses your home’s real measurements, insulation, windows and ductwork to work out how much cooling the house needs. Ask any company quoting a new system how they sized it.
Cowboys Air Conditioning & Heating has installed AC and heat pump systems in San Antonio since 2007, and you get the price in writing first. See AC installation and replacement, AC replacement cost in San Antonio and getting a second opinion.
Frequently asked questions
What size AC do I need for my house?
It depends on more than square footage: insulation, windows, sun, ductwork and ceiling height all matter. A load calculation (Manual J) gives the right size for your home.
How many BTUs is a ton of AC?
One ton of cooling equals 12,000 BTUs per hour. A 3-ton system is 36,000 BTUs per hour.
Is a bigger AC better?
No. An oversized AC cools fast but removes less humidity and cycles on and off more, which can leave the house clammy and wear parts sooner.
Should I replace my AC with the same size?
Not always. If the home has new windows, insulation or an addition, or the old system never worked well, the right size may be different. A load calculation will tell.
What is a Manual J load calculation?
It is the industry method for working out how much heating and cooling a home needs, using its size, insulation, windows, ductwork and other details.
Related service: AC installation and replacement · AC repair in San Antonio · AC replacement cost. Cowboy's AC answers 24/7 at (210) 495-7771.
