Size Matters! Right-Sizing a New Home Cooling System

In our last post, we talked about SEER and the importance of efficiency when choosing a new central air conditioner (which may be a good idea this year, if summer unfolds as predicted).

This week we turn our attention to one of the other critical factors when choosing a home cooling system: size.


To choose the right-sized air conditioner, you need to consider many factors – climate, the style of your home, the amount of insulation in your home, and more. But it’s well worth the trouble: a properly sized air-conditioning system can reduce energy usage by up to 35 percent.

Just remember that when it comes to air conditioner size, bigger is not always better. If the system is too large, it will short cycle – meaning the compressor will not run long enough to dehumidify your space. The A/C unit will also cycle on and off more often, causing wear and tear – and likely the premature breakdown of your system.

Although there are rules of thumb for estimating cooling load, these formulas fail to take into account the complexities of right sizing. To get a more accurate estimate, you’ll need help choosing a unit that’s right for your home and lifestyle.

Sizing using your current central A/C unit

One useful thing to know is the size of the cooling system that‘s already in place in your home. The problem is manufacturers make it tricky for you by coding the unit’s capacity into the model number on the outdoor unit.

For example, a model called CKL24-1 is a 2-ton unit. Why? Because there are 12,000 Btus per ton; the number 24 in the model number indicates the unit is 24,000 Btus; simply divide that number by 12,000 Btus and you get 2 tons.

Here are some conversions for popular sizes of units. Make sure you use the system model number for your calculation and not the serial number.

  • 18– 1.5 tons
  • 24 = 2 tons
  • 30 = 2.5 tons
  • 36 = 3 tons
  • 42 = 3.5 tons
  • 48 = 4 tons
  • 60 = 5 tons

While knowing the size of your current unit can help you estimate what’s needed to cool your home, it still pays to do the work to get the cooling load calculation as accurate as possible.

Contact us to get a FREE estimate on a new central air conditioner for your home – which includes an accurate cooling load assessment so you’ll get the right size A/C for your home! And make sure to ask us about our amazing seasonal special offers on new cooling systems!

For everything you need in home heating, trust the pros at Carroll Home Services – keeping Maryland homes warm for more than a century! Contact us to get started today!