Furnace Replacement Cost Calculator

A standard 80% AFUE furnace for a 2,000 sq ft home typically runs $3,500–$7,500 installed. High-efficiency 95%+ AFUE condensing furnaces add $1,500–$2,000 more but save 15–20% on annual gas bills. Costs vary by region, brand, and whether ductwork modifications or flue/venting upgrades are needed. The calculator provides a planning range — get at least 3 contractor quotes.

High-efficiency (95%+ AFUE) costs more upfront but saves 15–20% on gas bills annually. It also qualifies for federal tax credits and many utility rebates. However, it requires PVC venting (existing metal flue must be abandoned or shared with a water heater). If you plan to stay in the home 10+ years, high-efficiency usually pays for itself. In cold climates with high heating bills, the payback period is shorter.

Furnace capacity (BTU) must be determined by a Manual J load calculation — not just square footage. An oversized furnace short-cycles, wastes energy, and creates temperature swings. An undersized furnace can't keep up on the coldest days. A reputable HVAC contractor will perform the load calculation as part of their quote.

Gas furnaces typically last 15–20 years with proper maintenance. Signs that replacement is near: age over 15 years, frequent repairs (>$500/year), cracked heat exchanger (CO hazard), rust or corrosion, loud operation, or uneven heating. Replace before failure — emergency replacements in winter always cost more.

Assumptions (not a quote): 1,800 sq ft one-story in South Bend or Mishawaka, gas forced air, furnace ~18 years old, existing metal flue. Like-for-like 80% AFUE with Manual J often plans around $4,800–$6,200. High-efficiency 95%+ with PVC venting and condensate often plans around $6,800–$8,900. Compare 10-year gas savings vs upfront delta and your stay horizon. Pair with the local furnace market answers for citeable ranges.