How to Choose the Right Size AC Unit for Your Home

On December 26, 2015 by Himanshu

Choosing the proper sized air conditioning unit for your home can affect not only your comfort, but also your utility bill. If you choose a unit that’s too big, for example, you may use more electricity and experience excessive humidity in your home. If the system is too small, you may not be able to cool your house to a comfortable temperature. Take a few minutes and do some simple math to select the right sized air conditioner for your home.

Select the Right Type of Air Conditioner 

Right Type of Air Conditioner

There are several different types of air conditioners you can choose from. These include window units, portable air conditioners, built-in units or central air conditioning systems. If you plan to install an air conditioner in a single room, you’ll need to measure and calculate the square footage of the room. If you’ll be installing a central air conditioning system to cool your entire home, you’ll need to determine your home’s overall square footage.

Calculate the Optimal BTU Rating

Once you’ve determined the size of the space to be cooled, you’ll need to calculate the correct British Thermal Unit (BTU) rating that will best suit the room size. Other factors to consider when calculating the BTU rating include insulation levels, sun exposure, and climate type.

The BTU rating indicates how quickly and effectively the unit can cool the room. Generally, BTU ratings range from 5,000 to 20,000 units. The U.S. Department of Energy offers a few guidelines for determining the best BTU rating for different sized spaces:

  • 100 to 300 square feet: 5,100 to 7,000 BTUs
  • 300 to 550 square feet: 8,000 to 12,00 BTUs
  • 550 to 1,000 square feet: 14,000 to 18,000 BTUs
  • 1,000 to 1,200 square feet: 21,000 to 24,000 BTUs
  • 1,500 to 2,000 square feet: 30,000 BTUs
  • 2,000 to 2,500 square feet: 34,000 BTUs

Don’t forget to add other considerations into your BTU calculations, as well. Some basic guidelines are as follows:

  • Kitchens: add 4,000 BTUs
  • Shady location: decrease BTUs by 10 percent
  • Sunny location: increase BTUs by 10 percent
  • Occupied by more than one person: add 600 BTUs for each additional occupant

Understand Energy Efficiency Ratings

Energy Efficiency Ratings
Another consideration for choosing the right sized cooling unit is the system’s efficiency as measured by the energy efficiency ratio (EER). This is the ratio of the BTUs to the power input measured in watts. Essentially, the higher the EER rating of the system, the more efficient it is. When considering a cooling unit, you should look for an EER of at least 11, and you’ll find information about the EER on the unit’s Energy Guide label. Choose a unit that also carries the Energy Star label to ensure that the system meets efficiency guidelines established by the Environmental Protection Agency, along with the U.S. Department of Energy.

These guidelines can certainly help you select a cooling system for your home. When you’re ready to make the purchase, however, be sure to call in an HVAC professional to assist.

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