Replacing both your air conditioning system and furnace at the same time is a big financial decision for any homeowner. In 2025, the cost to replace air conditioning unit and furnace continues to rise due to new efficiency regulations, labor shortages, and inflation on materials. Many homeowners wonder if it’s better to replace both systems together or separately, and how much they should realistically budget for this project.
This guide will break down average replacement costs, factors that affect pricing, how system type impacts the bill, and why some homeowners actually save money by doing both at once.
Key Highlights
- The average cost to replace air conditioning unit and furnace together in 2025 is between $18,500 and $25,000.
- Replacing both systems at once can reduce labor costs and ensure compatibility.
- The cost to replace furnace alone ranges between $14,200 and $18,000, while AC units range from $14,000 to $17,000.
- Common add-ons such as furnace ignitor replacement or duct modifications increase the final price.
- Rebates and efficiency credits from the U.S. Department of Energy can reduce total project costs.
Why Homeowners Replace Furnace and AC Together
Most furnaces last about 15–20 years, while central air conditioners usually last 12–15 years. If one system fails near the end of its life, it often makes financial sense to replace both at once. This avoids compatibility issues between old and new systems and can save thousands in labor costs.
Contractors often offer discounts for bundling both replacements into a single job. Since the same ductwork, wiring, and installation team is involved, it reduces the total hours spent on-site. Homeowners who choose to replace only one system may end up paying more in the long run if the other fails soon after.
Average Cost to Replace Air Conditioning Unit and Furnace
The cost to replace air conditioning unit and furnace together in 2025 averages between $18,500 and $25,000 depending on system type, size, and efficiency.
If you only replace one system, the cost to replace furnace averages $14,200 to $18,000, while replacing just the AC ranges from $14,000 to $17,000. Bundling both together often results in a lower combined price than paying for them separately.
Gas Furnace and AC Replacement
Gas furnaces are the most common pairing with central AC. High-efficiency gas furnaces add to upfront cost but lower heating bills in the long term. Expect a bundled system replacement to cost between $19,000 and $24,500.
Electric Furnace and AC Replacement
Electric furnaces have a lower installation cost, but they are less efficient to run in colder climates. Paired with AC, expect $18,500 to $22,500 total. While the upfront cost is slightly lower, ongoing electric bills can be higher depending on local utility rates.
Factors That Influence Cost
Every home is different, and so are furnace and AC replacement costs. Several factors can push the price higher or lower.
System Size and Capacity
The size of the furnace and AC, measured in BTUs and tons respectively, impacts cost. Larger homes require bigger systems, which are more expensive. Contractors perform Manual J load calculations to size both systems accurately.
Efficiency Standards
Modern systems must meet updated SEER2 ratings for AC and AFUE standards for furnaces. High-efficiency systems cost more upfront but lower energy bills significantly. For example, an AC rated at 18 SEER2 can cut cooling costs by 30% compared to an older 10 SEER system.
Ductwork Condition
If your ducts are old, leaking, or improperly sized, contractors may recommend modifications or replacement. This can add $11,500 to $14,000 to the project.
Regional Labor Rates
Labor costs vary across the country. Urban areas typically pay higher rates than rural regions. Colder climates often lean toward higher-end furnaces, which also raise costs.
Add-Ons and Repairs
Simple fixes like furnace ignitor replacement can add a few hundred dollars if needed during installation. Other parts like blower motors, thermostats, or condensate pumps can raise the total bill.
Pros and Cons of Replacing Both Systems Together
Pros
- Lower combined labor costs
- Improved energy efficiency across both systems
- Longer-term compatibility between AC and furnace
- Access to bundled rebates and discounts
Cons
- Higher upfront cost compared to replacing just one unit
- May not be necessary if one system is fairly new
- Requires more planning and higher financing options
Rebates, Tax Credits, and Efficiency Programs
Federal and state programs can significantly reduce the cost to replace furnace and AC together. The Inflation Reduction Act provides tax credits for high-efficiency systems, while many local utilities offer rebates for upgrades.
The U.S. Department of Energy provides up-to-date information on available credits and programs. Homeowners can save hundreds or even thousands by choosing eligible systems and filing for these incentives.
When Replacement Makes the Most Sense
If your furnace and AC are both over 10 years old, it is worth considering replacing both. Compatibility issues often arise when pairing an older furnace with a new AC or vice versa. Replacing together ensures the systems are matched, efficient, and covered by a new warranty.
If your systems are relatively new, replacing just one may be fine. However, homeowners often regret staggering replacements when the second system fails within a few years.
Final Thoughts
The cost to replace air conditioning unit and furnace in 2025 ranges from $18,500 to $25,000 depending on type, efficiency, and installation needs. Replacing both together can lower labor costs, improve energy savings, and provide a fresh start with matched systems. While the cost to replace furnace alone may seem lower, homeowners should weigh long-term savings and rebates when deciding.
Even small repairs like furnace ignitor replacement can add to the total bill, but they are minor compared to a full replacement. By getting multiple quotes, exploring rebates, and choosing the right contractor, you can control costs and make a smart investment in your home’s comfort.
