HVAC systems are expensive to replace and getting more expensive as efficiency requirements increase. But pouring repair money into a system at the end of its life is also expensive.
The age question
- Central AC: 12-17 years
- Gas furnace: 15-25 years
- Heat pump: 10-15 years
- Boiler: 20-30 years
If your system is in the back half of its expected life and needs a major repair, replacement is usually the better economic call.
The 50% rule
If the repair cost is more than 50% of replacement, replace. Less than 50%, repair. Adjust threshold lower for systems already near end of life.
The refrigerant question
Older AC and heat pump systems may run on R-22 (Freon), which has been phased out since 2020. R-22 is no longer manufactured, so existing supply is extremely expensive. A leak in an R-22 system can cost more than a new system to recharge.
Modern systems run on R-410A or newer R-32 or R-454B. Manufacturers shifted from R-410A in 2025 due to updated EPA rules.
Repair history pattern
One repair is normal. Two unrelated repairs in 18 months is a pattern. Three is a warning.
The efficiency math
A 15-year-old AC at SEER 10 vs. a new one at SEER 15+ can mean 30-40% lower cooling costs. Over remaining lifespan, real money — especially in expensive electricity markets.
Federal and state incentives for heat pumps
Heat pumps — especially cold-climate heat pumps — qualify for federal tax credits and many state and utility rebate programs. The dollar amounts can be substantial. Check the Energy Star website for current programs before deciding.
The replacement landscape
Like-for-like
Gas furnace replaces gas furnace. Straightforward, lowest cost, lowest disruption.
Heat pump conversion
Replace gas furnace and AC with a single heat pump system. Higher upfront, dramatically lower operating cost in moderate climates, qualifies for the most generous incentives.
Hybrid (dual-fuel)
Heat pump for most of the year plus gas furnace for coldest weather. Bridges comfort and cost concerns in cold climates.