What the “ton” means for an A/C (and why it matters).

“Tons” is a measurement (between 1.5-5) of the size/cooling capacity of the air conditioner. Basically, the higher the tonnage, the more heat the AC can remove from your home.

The phrase a “ton of air conditioning” comes from a time when a literal ton of ice was used for cooling. One ton of cooling is the equivalent of 2,000 lbs of ice absorbing heat in 24 hours.

OK, sounds neat. Does that mean that a greater tonnage is always better?

No way! Unlike SEER (the AC’s energy efficiency rating), a bigger number does not mean better. Like a shoe fits a foot, the AC size need to fit your home’s cooling needs. No more. No less.

Here’s why.

Nasty effects of over-sizing and under-sizing the air conditioner

Like we said before, tonnage determines how well an AC can cool your home.

So if the AC is under-sized you’ll be uncomfortable during summer because it will struggle to cool your home to your thermostat setting. The AC will run longer, leading to high energy bills and a premature breakdown.

But If the AC is over-sized it will cool your home too quickly. What’s so bad about that?

Well, part of your air conditioner’s job is to dehumidify your home. So if it cools the home too quickly, it won’t run long enough to properly dehumidify the home, leaving you uncomfortable —even at a lower temperature setting.

Also, an air conditioner that cools the home too quickly will turn on and off too often, (called short cycling). And that’s basically like turning your car off and on every time you come a stop light: It’s wasteful, costly and reduces the system’s life

“How do I find the right air conditioner size?”

Short answer: You don’t. The contractor will.

Long answer: Calculating the right size of air conditioner for your home is complicated. And an AC installer won’t assume your current air conditioner is sized properly because it may be under or over-sized.

At any rate, an air conditioner installer should perform a Manual J heat load calculation on your home to determine what size air conditioner you need.

This calculation takes several factor into account, including:

  • Square footage of your home
  • Materials used in the construction of your home
  • Structure of your home (like if you have vaulted ceilings)
  • Your climate zone
  • Number of windows and skylights in your home
  • Home’s orientation in relation to the sun
  • How well your walls and attic are insulated

Need to know what air conditioner size you need? Or just need a question answered? Contact Santa Fe Air Conditioning and Heating for help.

Santa Fe Air Conditioning and Heating serves the Kansas City area.