🔥 Furnace and AC Replacement Cost Calculator

Typical replacement cost by home size (mid-range gas furnace + AC, good ductwork):

• Under 1,000 sq ft: $5,000–$9,000
• 1,000–1,500 sq ft: $6,000–$11,000
• 1,500–2,000 sq ft: $7,000–$12,500
• 2,000–2,500 sq ft: $8,000–$14,000
• 2,500–3,500 sq ft: $10,000–$17,000

Premium high-efficiency systems: Add 30–50% to above. Budget systems: subtract 20–25%.

Bundle savings: Replacing both at once saves $500–$1,500 vs. separate projects due to shared labor and single permit.

Replace whichever is older or failing first. Decision framework:

• If furnace is 20+ years old and AC is 12 years old: replace furnace now, plan AC replacement in 3–5 years when you can bundle
• If AC is failing and furnace is 15 years old: strongly consider bundling now — labor savings are significant
• If only one is failing and the other is under 10 years old: replace the failing unit only

When bundling makes financial sense: The older unit is 15+ years old, you're already paying for an HVAC contractor to mobilize, and the combined bundle saves $500–$1,500 in labor and permits.

Single-stage furnace: Runs at 100% output or off. Less expensive ($600–$1,200 less). Good for mild climates or tight budgets.

Two-stage furnace: Has a low (60–70%) and high (100%) output setting. Runs on low stage 80–90% of the time — more efficient, quieter, better humidity control, and more consistent temperatures.

Variable-speed (modulating) furnace: Runs at any output from 40–100%. Most comfortable, quietest, most efficient — and most expensive. Often pairs with variable-speed AC for maximum comfort and efficiency. Required for 97%+ AFUE ratings in most models.

Recommendation: Two-stage is the sweet spot for most homes. Variable-speed is worth the premium in large homes or climates with extreme temperature swings.

IRS Section 25C — Energy Efficient Home Improvement Credit:

• Gas furnace (97%+ AFUE): 30% credit, max $600/year
• Central AC (SEER2 ≥ 16 for split systems): 30% credit, max $600/year
• Both in the same tax year: Up to $1,200 total ($600 per component)

Additional credits for electric upgrades: If you upgrade your electrical panel as part of a heat pump conversion, the panel upgrade itself may qualify for 30% up to $600.

Claim process: Save all receipts and manufacturer certification statements. File IRS Form 5695 with your tax return. The credit is non-refundable (reduces tax owed, not a refund).

Standard replacement (existing ductwork in good condition): 1–2 days

• Morning: Remove old furnace and outdoor AC condenser, old refrigerant recovery
• Afternoon: Install new furnace, air handler, and coil; connect refrigerant lines
• Day 2 (if needed): Connect new condenser, pressure test, refrigerant charge, test heating and cooling, thermostat programming

Factors that extend timeline:

• New ductwork or duct modifications: add 1–3 days
• Electrical panel upgrade required: add 1 day (electrician)
• Gas line modifications: add half a day
• Permit inspection wait: 1–3 days in some areas

Upgrading from old system to new high-efficiency — annual savings estimates for 2,000 sq ft home:

• Old 60% AFUE furnace → 96% AFUE: Save $350–$600/year on heating
• Old 80% AFUE → 96% AFUE: Save $150–$280/year on heating
• Old SEER 10 AC → SEER2 16 AC: Save $200–$400/year on cooling
• Old SEER 13 AC → SEER2 16 AC: Save $80–$150/year on cooling

Payback period examples (mid-range upgrade premium ~$1,200):

• Cold climate (Chicago): Furnace upgrade payback 4–6 years
• Hot climate (Phoenix): AC upgrade payback 3–5 years
• Combined upgrade in cold + hot climate: Payback 4–7 years