Should You Replace Your Furnace and AC at the Same Time?
Should You Replace Your Furnace and AC at the Same Time?
Michael Carlson - 7/09/2025
If you’re replacing your air conditioner, should you replace your furnace at the same time? What about the reverse?
In many cases, taking on both tasks at the same time is more energy-efficient and cost-effective. Although furnaces and air conditioners have opposite roles in keeping your home comfortable, they often work in tandem to accomplish these goals. For example, in a split air conditioner system, your furnace and AC unit may share the same blower fan and use the same ductwork to move heated or cooled air through your home.
In this piece, we’ll break down some of the top reasons to consider replacing both components of your HVAC at the same time.
Compatibility Between Furnace and Air Conditioner
Two components play a role in furnace and air conditioner compatibility: size and communication.
Put simply, bigger units can handle more air, more quickly, making it easier to heat or cool your house. The interconnected nature of HVAC, however, means that the smaller unit is often your limiting factor. Putting in a larger AC unit won’t make your house any more comfortable if existing HVAC frameworks can’t handle higher air flow rates.
The second compatibility challenge is communication. Newer furnaces and AC units often use smart technology and sensors to communicate with your thermostat and determine optimal heating and cooling schedules. In addition, many companies have proprietary versions of this technology. If you have an older AC unit but buy a new furnace, you may be missing out on key benefits. And if you purchase new HVAC solutions from two different manufacturers, they may not work in tandem.
Cost Implications of Replacing Both Units
Replacing both your furnace and AC at the same time is expensive. Forbes notes that the average cost of a new AC unit with installation is $5,900, while the average cost of a newly-installed furnace is $4,700.
While this is a significant amount of money to spend up front, there are several potential benefits to a dual replacement approach. First is a reduction in labor costs. Since your AC and furnace are being installed simultaneously, your total labor costs are lower. In addition, this ensures that the units you purchase are compatible.
Next up are long-term savings. New units are more efficient than their older counterparts, meaning they use less energy to heat or cool your home. This leads to lower energy bills over time, which can help offset the cost of replacement. It’s also worth considering how long air conditioners last. Generally, units that are more than a decade old start to experience significant efficiency losses due to older parts and general wear and tear.
Energy Efficiency Benefits
Newer HVAC units are more efficient and offer a reduced environmental impact. Consider Seasonal Energy Efficiency Ratio (SEER) and Annual Fuel Utilization Efficiency (AFUE) ratings for AC units and furnaces.
The higher the SEER rating, the more efficient an AC system is. Older units often had SEER ratings of just 8 or 9, while modern air conditioners offer SEER ratings between 13.4 and 17.2.
AFUE, meanwhile, is a percentage. The higher the percentage, the more efficient the furnace at turning energy into heat. Furnaces installed 10-15 years ago had AUPE ratings of just 70%-75%. Today, these numbers range from 90% to 98%.
The refrigerant used in AC units has also changed. Older systems used R-22, or freon, which contributes to ozone layer depletion. Newer units rely on R-410A, which is more environmentally friendly and transfers heat more efficiently than freon.
Finally, newer systems now leverage embedded sensors and AI solutions to improve the efficiency of your heating and cooling over time.
Long-Term Savings and Performance Improvements
Choosing to replace your furnace when replacing your air conditioner offers three long-term benefits: Increased comfort, reduced costs, and improved home value.
- Increased Comfort — Newer systems heat and cool your home more quickly.
- Reduced Costs — Modern AC and furnaces are more efficient, meaning you pay less to keep your house warm or cool.
- Improved Home Value — High-quality systems add to the overall value of your home, making it more attractive to prospective buyers if you choose to move.
Doubling Down: The Case for Simultaneous Replacements
Should your AC and furnace be replaced at the same time? While initial costs are higher, long-term savings and efficiency often outweigh this spending.
By partnering with a trusted HVAC company to handle these replacements, you get the benefit of compatible technologies that are ideally sized for your home and make living more comfortable without breaking your budget.