How much does a furnace cost?

Installed: gas (standard 80%): $2,500-$4,000. Gas (high-efficiency 90-98%): $3,500-$6,000. Electric: $1,500-$3,500. Oil: $3,000-$6,000. National average: $3,500-$5,000 (gas furnace replacement). Factors: efficiency rating, size, brand, installation complexity. Operating cost: gas: $500-$1,200/year. Electric: $1,000-$2,500/year. Best value: a 95-96% AFUE gas furnace balances upfront cost with long-term savings.

How long does a furnace last?

Gas: 15-25 years (average 18). Electric: 15-20 years. Oil: 15-25 years. Factors: maintenance (annual tune-ups extend life 3-5 years). Filter changes (dirty filters strain the system). Quality of installation. Usage (mild climates extend life). Signs of replacement: age (15+ years). Frequent repairs. Uneven heating. Rising gas bills. Yellow burner flame (should be blue). Cracked heat exchanger (safety issue, replace immediately). Excessive dust despite clean filters. Key: a cracked heat exchanger can leak carbon monoxide. If detected, replace the furnace immediately.

How often should I change my furnace filter?

1-inch fiberglass: every 30 days. 1-inch pleated: every 60-90 days. 4-inch pleated: every 6-12 months. Factors that increase frequency: pets (pet hair clogs filters faster). Allergies (change more often for better air quality). Construction or renovation (dust). Running fan continuously. Check monthly: hold the filter up to light. If you can't see through it, replace it. Importance: a dirty filter is the number one cause of HVAC problems. Restricts airflow. Causes overheating. Shortens system life. Increases energy bills. Reduces air quality.

Gas vs electric furnace?

Gas: operating cost: $500-$1,200/year. Upfront: $2,500-$6,000. Powerful heat (warms faster). Requires gas line. Produces combustion gases. 80-98% efficiency. Electric: operating cost: $1,000-$2,500/year. Upfront: $1,500-$3,500. Less powerful heat (slower). No gas line needed. No combustion (safer). 100% efficiency (but electricity is expensive). Best alternative: a heat pump is 2-3x more efficient than an electric furnace and can replace both furnace and AC. Consider a heat pump before choosing an electric furnace.

Home Improvement

Furnace Guide: Types, Cost & Maintenance

Lumberama Editorial Team, Heating & Furnace Specialists Nov 30, 2026 7 min read

Furnace Types

Gas furnace: Most popular in the US. Burns natural gas. Efficiency: 80-98% AFUE. Cost: $2,500-$6,000 (installed). Standard efficiency (80% AFUE): vents through chimney. High efficiency (90-98% AFUE): vents through PVC pipe (no chimney needed). Pros: powerful heat, lower fuel cost than electric. Cons: requires gas line, produces combustion gases.

Electric furnace: Resistance heating elements. Efficiency: 100% AFUE (but electricity costs more per BTU). Cost: $1,500-$3,500 (installed). Pros: no gas line, no combustion, simple. Cons: expensive to operate (2-3x gas in most areas). Best for mild climates or backup.

Oil furnace: Burns heating oil. Cost: $3,000-$6,000 (installed). Common in Northeast where natural gas isn't available. Requires oil tank and delivery. Declining in popularity.

Two-stage and modulating: Single-stage: full blast or off. Most basic. Two-stage: high and low settings. Better comfort, quieter. Cost: add $500-$1,000. Modulating: adjusts output in tiny increments. Best comfort and efficiency. Cost: add $1,000-$2,000.

Cost

Furnace replacement (installed): Gas (standard 80%): $2,500-$4,000. Gas (high-efficiency 90-98%): $3,500-$6,000. Electric: $1,500-$3,500. Oil: $3,000-$6,000.

Cost factors: Efficiency rating. Size (BTU output). Brand. Installation complexity (ductwork, venting). Location (labor rates vary).

Operating cost per year: Gas furnace: $500-$1,200. Electric furnace: $1,000-$2,500. Oil furnace: $700-$1,500. Heat pump: $300-$800 (for comparison).

Repairs: Ignitor replacement: $150-$300. Blower motor: $300-$600. Heat exchanger: $500-$1,500 (often means replacement). Control board: $200-$500. Average repair: $200-$500.

Maintenance

DIY maintenance: Change filter every 1-3 months (most important thing you can do). Keep area around furnace clear. Check thermostat batteries annually. Ensure vents and registers are open and unblocked.

Professional tune-up (annually in fall): Inspect heat exchanger for cracks. Clean and adjust burners. Check gas connections. Test safety controls. Lubricate moving parts. Check airflow. Cost: $80-$150.

Filter types: Fiberglass (basic): $1-$5. MERV 8 (standard pleated): $5-$15. Good balance of filtration and airflow. MERV 11-13 (high filtration): $10-$25. Catches smaller particles. HEPA (hospital-grade): not recommended for most furnaces (too restrictive).

Lifespan: Gas furnace: 15-25 years (average 18). Electric: 15-20 years. Oil: 15-25 years. Key factors: maintenance quality, usage, and installation quality.