Should you replace your AC and furnace at the same time? Often, yes: if the furnace is more than 15 years old, or you’re upgrading to a higher-efficiency AC, replacing both together usually makes sense, according to HomeGuide. Angi puts the combined job at about $7,500 on average, typically $5,000 to $12,500.
Below, we compare the costs, explain why matched equipment matters, cover the refrigerant rules behind many 2026 quotes and show when replacing only one unit is the better call. Information checked on November 4, 2026.
Cost to replace the AC and furnace at the same time
| Source | Furnace + AC replacement | Notes |
|---|---|---|
| Angi (2026 data) | $5,000–$12,500 | $7,500 average |
| HomeGuide (Aug. 27, 2025) | $5,000–$11,000 | $8,000 average; existing ductwork |
| HomeGuide (Aug. 27, 2025) | $7,000–$16,000 | With new or replaced ductwork |
For comparison, Angi puts a furnace alone at about $4,800 on average and a central AC installation at $3,900 to $8,000. Meanwhile, HomeGuide says a new furnace and AC cost $3 to $6 per square foot, or $6,000 to $12,000 for a 2,000-square-foot house.
Brand example: Trane prices by product line
| Trane line | Central AC | 80% AFUE furnace | 96% AFUE furnace |
|---|---|---|---|
| Premier (variable) | $11,525–$13,669 | $6,000–$6,386 | $7,569–$8,390 |
| Priority (multi-stage) | $8,573–$10,671 | $5,530–$5,934 | $6,851–$7,412 |
| Choice (single-stage) | $6,568–$8,544 | $5,093–$5,481 | $6,630–$6,946 |
Why replacing both at once often makes sense
- Shared blower: your furnace and AC share the same air handler, or blower, Angi notes. In addition, HomeGuide says replacing the outdoor AC without the indoor furnace blower lowers efficiency and may cause premature failure.
- Rated efficiency: contractors match the furnace, coil and condenser so the system reaches its SEER2 and AFUE targets, according to Angi.
- Warranty: manufacturers aren’t obligated to honor warranties on new systems combined with older ones, Angi says. Similarly, This Old House warns that mixing old and new components can reduce efficiency and void warranties.
- One installation: duct, electrical and gas work happens in a single job, so you avoid paying for a second installation later.
- Age: ENERGY STAR suggests considering replacement when an AC is more than 10 years old or a furnace is more than 15 years old.
How the 2026 refrigerant rules affect your decision
Most new AC systems now use A2L refrigerants such as R-454B or R-32. That matters because North Carolina’s Office of State Fire Marshal says you must replace an existing indoor coil or air handler built for R-410A when you install an A2L outdoor unit. As a result, a new AC usually means at least a new indoor coil.
An existing gas furnace, however, may stay in place if the manufacturer’s instructions allow it, according to the same guidance. Some instructions require extra steps, such as a minimum airflow or connecting the AC’s leak detection system to the furnace fan. So ask your contractor whether the manufacturer approves your current furnace for the new AC.
Meanwhile, leftover R-410A equipment can still be installed in most states after EPA’s May 2026 rule change, except in New York. Our AC replacement cost guide explains the details.
When to replace only one unit
Replacing both isn’t always the best value. For instance, HomeGuide suggests considering only a new blower motor if the furnace is less than 15 years old. Likewise, This Old House notes that newer systems with minor issues can usually be repaired. Replacing just one unit can make sense when:
- Your furnace is under 15 years old, works well and suits the new AC.
- Repairs are small compared with the cost of a new system.
- You’d rather switch to a heat pump. In that case, compare it with a new AC first; our heat pump cost guide shows installed prices.
Should you replace your AC and furnace at the same time? Checklist
- First, check the age of both units; ENERGY STAR flags ACs over 10 years and furnaces over 15 years.
- Get a load calculation so both units fit your home’s actual load. Our guide on what size AC you need explains how.
- Ask for one quote for both units and separate quotes for each, so you can see the real savings.
- Confirm that the furnace, coil and condenser are a matched combination with a published SEER2 rating.
- Ask which refrigerant the new AC uses and whether your furnace works with it.
- Finally, compare warranties, including labor coverage.
Related guides: See also our guide on AC coil replacement cost. You can also get a personalized estimate with our HVAC replacement cost calculator.
FAQ
Is it cheaper to replace the AC and furnace at the same time?
Usually, yes, in total. Angi says installing both together will likely cost less overall than two separate jobs, because the contractor coordinates the labor. However, neither Angi nor HomeGuide publishes an exact savings figure, so compare a combined quote with separate quotes.
How long do a furnace and an AC last?
Angi says a modern furnace lasts 15 to 20 years and a central AC 12 to 15 years. HomeGuide, by contrast, gives 15 to 30 years for furnaces and 15 to 20 years for AC units.
Can I replace my AC without replacing my furnace?
Yes, in many cases. Still, you’ll usually need a new indoor coil, and the furnace must be compatible with the new AC, according to the North Carolina fire marshal guidance. Therefore, ask your contractor to confirm compatibility in writing.
How long does it take to replace the AC and furnace at the same time?
HomeGuide says installing a new HVAC system takes 1 to 2 days with existing ductwork, or 3 to 5 days with new ductwork.
Sources and review
Sources: Angi, new furnace and AC cost (2026 data); HomeGuide, new HVAC system cost (August 27, 2025); Trane, 2026 HVAC replacement cost guide; This Old House, HVAC replacement cost (September 2, 2026); ENERGY STAR, when is it time to replace?; North Carolina Office of State Fire Marshal, A2L partial replacement interpretation (June 6, 2025); ACHR News, EPA removes R-410A installation deadline (May 21, 2026). All checked on November 4, 2026.
Written by: HVAC Switch. Last updated: November 4, 2026. Read our editorial policy to learn how we research prices, or contact us if you spot an error.