AC Replacement: A Buying Guide
Learn what you need to consider when it’s time to replace your central AC unit.
By Anne Fonda
Whether your old air conditioner finally bit the dust, you’re tired of costly AC repairs, or you want to upgrade to a more energy-efficient AC system, we’ve got you covered. Air conditioner replacement doesn’t have to be hard.
If this is the first time you’ve had to replace an AC unit, you should know there are probably a lot more options than you thought possible. The combination of features and ratings can be dizzying. Making an informed choice comes down to doing your homework.
We’ve put together this buyer’s guide to help you. You’ll learn about the top factors to consider when replacing your central air conditioning unit, including:
Doing your homework and understanding these various factors can help ensure you ask the right questions when HVAC companies send a representative to your home to give you a quote for an AC unit replacement.
Getting a properly sized central air conditioner is a critical part of your AC replacement journey. HVAC sizing should be done by an HVAC professional who takes the time to do it right, performing a precise load calculation to determine the AC unit size that is suitable for your home.
Cooling capacity, or size, is measured in tons. A ton is equal to 12,000 BTUs, or British Thermal Units. A 5-ton AC unit can cool a 3,000 sq. ft. home, while a 2-ton AC unit could cool a 1,200 sq. ft. home. However, this can vary depending on the type of insulation, windows, or siding on your home. That’s why it’s important to have a qualified technician perform an actual load calculation on your home.
You want a replacement air conditioner that is sized just right for your home. An air conditioner that is either too big or too small will waste energy and fail to deliver the comfort you deserve – no matter how efficient the unit is.
There are two important air conditioner energy-efficiency ratings - SEER2 and EER2. The most energy-efficient air conditioners will have high ratings in both categories.
SEER2
SEER2 stands for seasonal energy efficiency ratio. It measures an AC unit’s cooling efficiency in a temperature range of 65-104° F. The higher the SEER2, the more efficient the air conditioner is.
EER2
EER2 stands for energy efficiency ratio. It also measures an air conditioner’s cooling efficiency but at a specific temperature of 95°F rather than in a temperature range. If you live in a hot climate such as south Texas, the desert southwest, or Florida where temperatures exceed 95 degrees for weeks at a time, the EER2 rating may be more important to you than the SEER2 rating.
Learn all about HVAC efficiency metrics.
How many cooling stages your new central air unit has will combine with the SEER2 and EER2 ratings to provide you with a range of energy efficiencies. Let’s take a look at the options.
Single-stage
A single-stage air conditioner is either on or off. When it’s on, it runs at 100% capacity until the temperature reaches the set point on the thermostat. Then it shuts off. It will turn on again when the temperature rises.
This frequent on/off cycle can result in high operating costs.
Two-stage
A two-stage, or two-speed, air conditioner takes cooling up a notch and regulates the temperature in your home a little better. While single-stage systems run at 100% capacity, two-stage air conditioners operate at a high or low speed. In most cases, the low stage operates at around 70% +/- capacity, while the high stage operates at 100% capacity.
Multi-speed
A new kid on the block at Trane, our multi-speed air conditioner offers more precise comfort than a two-stage unit, without the premium price tag of our most efficient variable speed systems. Compared to a 2-stage cooling system, you get higher efficiency, up to 4 additional operating speeds, and more heating and cooling capacity at extreme temperatures.
Variable-speed
A variable-speed HVAC system is the most energy-efficient air conditioning system available. The system takes the indoor and outdoor temperatures and humidity levels, calculates the run time needed to reach your set temperature, and then determines the appropriate output.
Variable-speed air conditioners can operate anywhere from 25-100% capacity to precisely meet and maintain your desired temperature within half a degree. Because they can operate at lower speeds, they consume less power, which makes them the least expensive to operate over the long term.
Cost shouldn’t be the only factor you consider, but we know it’s a big one for most homeowners. Think both in terms of upfront costs and future cost savings. The most energy-efficient air conditioner will cost more than a lower SEER2 single-stage AC unit, but it can result in lower utility bills for years to come.
Some of the factors that will impact your air conditioning replacement cost include:
- The size and layout of your home
- The size of the AC unit you need will vary based on the size of your home, climate, sun exposure, insulation, exterior construction materials (brick, stucco, vinyl)
- The age of your home and the condition of the ductwork
- If you’re replacing the furnace at the same time
- The air conditioner brand you choose – lower-priced brands may not last as long as premium brands
- The efficiency ratings of the units
- Single-stage, two-stage, multi-stage, or variable-speed system
- Add-on comfort features such as a zoning system, whole-house air cleaner, etc.
- Who does the installation
- Labor costs in your area
- Available tax credits or rebates
Each home is different, and every family’s needs are different. The best way to get specifics on the cost to replace an AC system is to gather quotes from several HVAC companies in your area.
If you’re a new homeowner or new to the area and you’re not sure who to work with, read our blog on how to choose the best HVAC contractor for some tips. When each company representative comes to your home to give you a quote, ask them about all of the factors we’ve discussed here.
Ask them to help you run the numbers on how much an energy-efficient air conditioner can save you on your energy bills. The cost savings might be expressed as a percentage. But remember, you will only get the most out of a new system if your home is properly weatherized and you utilize a smart thermostat for optimal energy usage.
Check a company’s reviews and reputation – because a new air conditioner is only as good as the installation.
Work with the HVAC experts
If it’s time to replace your air conditioner or perhaps replace your furnace and air conditioner at the same time, we can help. Contact your local Trane Comfort Specialist to discuss your options.
They’ll listen to what you want, ask what you need, and evaluate your home cooling needs. You can get quotes on multiple units and determine what the right choice is for your home and budget.
Anne Fonda, Content Writer
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Mark Woodruff, Senior Product Manager, Ducted Outdoor
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