When installing a new central air conditioning unit or replacing your old unit, you have quite a few different options to choose from. The brand or manufacturer is one thing you should always focus on as units from the top-rated and most-trusted brands like Carrier will typically perform more effectively, last longer and have fewer issues.

The two other main things you’ll want to look at are the Seasonal Energy Efficiency Ratio or SEER rating and the compressor speed, i.e. whether it is single-stage, two-stage or variable-speed. To help you make a more informed decision on your new AC unit, here is a full overview of both SEER ratings and compressor speed so that you can better understand the differences between various air conditioners.

Understanding SEER Ratings

SEER is a measurement of how much total electricity an air conditioner uses compared to its total cooling capacity as measured in BTUs (British Thermal Units). The higher a unit’s SEER rating is, the more effectively it will cool and the less energy it will use.

Any new central air conditioner in Georgia or anywhere else in the southern US is required by law to be at least 15 SEER. This is an increase from the previous SEER standards as a new law went into effect at the start of 2023 that raised the minimum SEER requirements across the country. If your current AC was installed any time before 2006, it may only be 13 SEER as this was the minimum up until the start of that year.

The SEER rating is an essential factor to consider when looking at new AC units since it will directly affect how much a unit costs and how high your cooling bills will be. As you might expect, units with a higher SEER rating are quite a bit more expensive than lower-rated units. A 17 SEER unit will typically cost at least $1,000 to $1,500 more than a 15 SEER unit of the same size. If you’re looking at a 21 SEER unit, the price could easily go up by $3,000 to $5,000 more.

Despite the huge price difference, a higher SEER unit is often still the better long-term financial decision as the increased energy savings will typically offset the higher initial cost. For each additional SEER value, energy efficiency increases by approximately 7%. This means if you were to opt for a 20 SEER unit, your yearly cooling costs would be around 35% less than if you went with a 15 SEER unit.

Let’s say you have a large home with a 5-ton AC unit. In this case, your yearly cooling bills could be around $300 lower if you opted for a 20 SEER unit compared to a basic 15 SEER AC. Since most new AC units should last around 15 years, this means that a 20 SEER unit could potentially save you around $4,500 in energy costs over the life of the unit. This is why it is always important to consider both the total cost of the new unit and its estimated lifetime energy costs in order to find the unit that offers the best value for the money.

Compressor Speeds and AC Stages

In addition to SEER ratings, you’ll also want to pay attention to compressor speeds or how many stages the unit has as this will have an impact on both your energy bills and your overall comfort. Basic central AC units are generally always single-stage, which means that they can only run at one speed. While Georgia’s high heat and humidity means that any AC may need to run at full power during the hottest parts of the year, there are also many times in the evenings, early mornings and during spring and fall when you wouldn’t always need your AC to run at full power.

A two-stage AC will generally always use less energy overall than a single-stage unit as it can run at a lower speed any time when less cooling is required. In fact, even in Georgia, a two-stage unit will run most often at the lower power setting except during extremely hot times or when your home’s temperature is more than 5 to 8 degrees higher than the thermostat setting. Whenever a two-stage unit first turns on, it always starts at the lower power setting and will only switch to full power when it needs to provide much more cooling.

Since it is producing less cooling at a time when running on low power, a two-stage unit will typically run for much longer each time than a single-stage unit. However, your overall cooling costs will still be much less even though the unit runs for longer since it uses far less electricity when running at low power. The fact that a two-stage unit will always run longer also means that your home’s temperature will stay more consistent and not fluctuate as much as it would with a single-stage AC.

Two-stage ACs are also far more effective at controlling indoor humidity for the same reason, which is another reason why they can be a great option in Georgia. Simply put, the longer the unit runs, the more moisture it will remove from your home’s air. This is also another reason why two-stage units use less energy as high indoor humidity would otherwise reduce the unit’s cooling capacity and result in higher energy usage.

Variable-speed ACs are even more efficient as they typically have at least five power settings instead of only one or two. This means that a variable-speed AC will be even more effective at maintaining a consistent temperature since it can constantly adjust its speed based on how much cooling is currently needed.

Variable-speed ACs are also paired with a variable-speed blower that can speed up or slow down the rate at which air circulates through the system. Unfortunately, this variable-speed blower can add quite a bit to the installation cost since most residential HVAC systems only have a single-speed blower. This is important to consider since you will likely need to have a new blower installed. For this reason, you may still be better off opting for a two-stage unit if your blower isn’t all that old and still working properly unless you’re willing to pay the extra cost for a new blower.

Another advantage of both two-stage and variable-speed ACs is that they are typically much quieter than single-stage units. The noise level can still be similar whenever these units need to run at full power, but again, this typically won’t happen all that often since they are more effective at keeping your home’s temperature from suddenly spiking.

At Bardi Heating, Cooling & Plumbing, we carry a wide selection of Carrier air conditioners and our team can help you decide which unit best meets your needs and your budget. We also install furnaces, heat pumps, smart thermostats and whole-home air purifiers, and we can assist with HVAC repairs and maintenance as well as any residential plumbing services. For more information on our AC installation services or if you need to schedule any service in Norcross or the Atlanta area, contact Bardi Heating, Cooling & Plumbing today.

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