How a New AirConditioner Is Sized

A new central air conditioner is a major investment for your home. When it comes time to replace your cooling equipment, finding the correct size is a critical step. A unit that is too small will run constantly and struggle to cool your rooms during the hottest months. A unit that is too large cools in short bursts and turns off and on too often.

Many people believe that determining the size of a new unit is a simple calculation based on the size of the house. That approach is flawed. Square footage alone is never enough to determine the correct equipment capacity. A proper estimate looks at the whole home before recommending a size. This involves evaluating:

• The individual rooms and how your family uses the house.
• The level of insulation in the attic and walls.
• The quality of the windows and overall sun exposure.
• The condition of the existing ductwork.

How the Desert Climate Impacts Sizing

Living in the Las Vegas valley means dealing with extreme summer conditions. According to the National Weather Service, July brings an average high of 104.5 degrees. About 78 days a year reach 100 degrees, and about nine days reach 110 degrees. The all-time record high is 120 degrees, recorded on July 7, 2024. Furthermore, about 47 nights a year stay at 80 degrees or warmer.

Your outdoor unit sits in direct sun and dust for months at a time. The monsoon season in July and August brings strong winds and blowing dust. Indoor units in many valley homes are located in the attic, a garage or a hall closet, which exposes them to high temperatures. All of these environmental factors affect how hard your cooling system must work, which in turn influences the capacity required to cool your living spaces effectively.

The Role of Windows and Insulation

The amount of heat entering your home directly impacts the size of the air conditioner you need. Homes with large windows facing the afternoon sun will absorb a significant amount of heat. If those windows are older or lack proper sealing, the heat gain is even greater. Insulation also plays a major role. A well-insulated home retains cooled air much better than a poorly insulated one.

When an estimator visits your property, they will look at these specific details. Two houses with the same square footage might require different equipment sizes if one has shaded, double-pane windows and thick attic insulation, while the other has single-pane windows in direct sunlight. The estimate also looks at how your family uses the house.

Evaluating Existing Ductwork

The duct system is responsible for delivering conditioned air to every room. If the existing ductwork is undersized or damaged, a new high-capacity air conditioner will not perform well. According to ENERGY STAR, in a typical house about 20 to 30 percent of the air moving through the ducts is lost to leaks, holes and poorly connected ducts.

Our team assesses the existing ductwork during the visit. We look for areas that require duct repair, sealing, replacement or airflow balancing. We do not offer duct cleaning. Fixing duct problems helps the new equipment move air to every room. This is especially important for two-story homes, which often have uneven temperatures between floors.

Efficiency and Refrigerant Updates

When selecting new equipment, you must also account for current federal regulations. The United States Department of Energy places Nevada in the Southwest region. Since January 1, 2023, new split central air conditioners in this region must meet a minimum efficiency of 14.3 SEER2, plus an EER2 minimum for systems under 45,000 BTU. Heat pumps nationwide require 14.3 SEER2 and 7.5 HSPF2.

Refrigerant standards have also changed. According to the Environmental Protection Agency, since January 1, 2025, new residential air conditioners and heat pumps are made for lower-impact refrigerants such as R-454B and R-32 instead of older options like R-410A. Anyone who maintains, services or repairs equipment containing refrigerant must hold EPA Section 608 certification.

Making the Final Choice

Carrier and ENERGY STAR note that central air conditioners commonly last about 15 to 20 years. ENERGY STAR suggests considering replacement of an air conditioner older than 10 years. However, we never recommend replacement on age alone.

During our free, in-home, written estimate, we provide two or three equipment options when more than one fits your needs. Elena Navarro reviews every replacement estimate before it goes to the homeowner. We also help homeowners check which NV Energy PowerShift programs apply to the equipment they choose. For new system installations, Kestrel Heating & Air provides a two-year labor warranty in addition to the parts warranty set by the manufacturer. At the walkthrough after a new installation, the installer helps the homeowner register the equipment with the manufacturer where registration is required. Our AC replacement services and the Kestrel Comfort Club are designed to help your home handle the summer heat.