Furnace Repair: What It Costs, Common Problems & When to Replace

Most homeowners pay $150 to $600 for a furnace repair, though the total depends heavily on what's wrong. A simple fix like cleaning a flame sensor might run $75 to $300, while replacing a blower motor can cost $300 to $2,500.

The national average for a furnace repair falls between $300 and $500, including parts and labor. On the low end, minor repairs like a bad thermocouple or a faulty limit switch cost $65 to $300. On the high end, major component failures — a cracked heat exchanger, for example — can run $500 to $3,500 and sometimes make replacement the better option.

A few things to keep in mind before you call a technician:

• Diagnostic fees run $75 to $200. Many companies credit this toward the repair if you go ahead with the work.
• Emergency and after-hours repairs cost 1.5x to 3x the standard rate. If it's not a safety issue, waiting until morning can save you hundreds.
• Location matters. Repair costs in the Northeast and West Coast run 10–25% higher than the South and Midwest, driven by higher labor rates and cost of living.
• Furnace type matters. Electric furnaces are the cheapest to repair ($50–$400). Oil furnaces are the most expensive ($400–$2,500).

The sections below break down costs by specific component, by symptom, and by furnace type — so you can estimate what your repair might cost before a technician arrives. You can also use our furnace repair cost calculator for a personalized estimate based on your specific situation.

Most people don't know which furnace component is failing — they just know something is wrong. Here's what common furnace symptoms typically point to, and what the repair usually costs.

A few of these have simple, free fixes. Short cycling is often caused by a dirty air filter ($5–$30 to replace yourself). A burning smell when you first turn on the furnace in fall is usually just dust burning off and is harmless. But if a burning smell persists, shut the furnace off and call a technician — it could indicate an electrical problem or cracked heat exchanger.

If you smell gas or your carbon monoxide detector goes off, leave your home immediately and call 911 or your gas company. Do not attempt to diagnose or fix the issue yourself.

Not all furnaces cost the same to repair. Electric furnaces have fewer complex components and are the cheapest to fix. Oil furnaces are the most expensive because of specialized parts and soot buildup that complicates repairs.

Gas furnaces are by far the most common in the US, accounting for about 45% of residential heating systems. They fall in the middle for repair costs. The wide range ($100–$1,200) reflects the difference between a minor fix like a flame sensor ($75–$300) and a major one like replacing a gas valve or blower motor.

Propane furnaces work similarly to natural gas units, so repair costs are comparable. The main difference is fuel cost — propane typically costs more per BTU than natural gas.

Oil furnaces cost the most to repair. They require specialized technicians, and components like burner assemblies and oil nozzles need more frequent attention due to carbon buildup. If you have an oil furnace approaching 20 years, replacement with a gas or high-efficiency electric system often makes more financial sense than continued repairs.

When your furnace fails at 2 AM in January, you'll pay a premium. Emergency and after-hours repairs typically cost 1.5x to 3x the standard rate.

For perspective, an ignitor replacement that costs $200 during regular business hours can run $400 or more on a weekend night.

When you need emergency service (don't wait):

• You smell gas
• Your carbon monoxide detector alarms
• The furnace won't shut off
• You see visible damage, sparking, or smoke

When you can probably wait until morning:

• The furnace won't turn on but your home is above 55°F
• You hear unusual noises but the furnace is still heating
• The furnace is short cycling

If your home won't stay above 55°F, you need emergency service — not just for comfort, but because frozen pipes can cause thousands of dollars in water damage. Use space heaters as a temporary bridge (keep them away from anything flammable) and call for service.

Eight factors determine what you'll actually pay for a furnace repair.

1. The component that needs repair. This is the biggest factor. A flame sensor cleaning runs $75–$300. A heat exchanger replacement costs $500–$3,500. See the full component cost table above.

2. Your furnace's age. Older furnaces cost more to repair for two reasons: parts are harder to source (manufacturers discontinue them), and aging systems tend to have multiple failing components. A 15-year-old furnace repair often becomes a "fix this, then that breaks next" situation.

3. Furnace type. Electric furnaces are cheapest to repair. Gas furnaces are moderate. Oil furnaces are most expensive. See the type comparison above.

4. Where you live. HVAC labor rates vary significantly. Technicians in Washington state average $32/hour, while those in Florida average $21/hour (BLS data). The Northeast and West Coast see repair costs 10–25% above the national average.

5. Time of year. Peak heating season (November through February) means higher demand, longer wait times, and 15–25% markups. Off-season repairs in spring and summer are typically cheaper and faster.

6. Emergency vs. scheduled service. After-hours and emergency calls cost 1.5x to 3x standard rates. If it's not a safety emergency, scheduling a next-day appointment saves real money.

7. Warranty status. If your furnace is under warranty, parts may be covered. Most manufacturers offer 5–10 year parts warranties. Many offer lifetime heat exchanger warranties on higher-end models. Labor is usually not covered unless you purchased an extended warranty.

8. Your contractor. Pricing varies between contractors. Some charge flat rates per repair, others bill hourly. Always get 2–3 quotes for non-emergency repairs. Ask whether the diagnostic fee is credited toward the repair — many companies do this.

At some point, continuing to repair an old furnace costs more than replacing it. Three rules of thumb can help you decide.

The $5,000 Rule

Multiply your furnace's age (in years) by the estimated repair cost. If the result exceeds $5,000, replacement is the better investment.

• 12-year-old furnace, $350 repair: 12 × $350 = $4,200 → Repair
• 15-year-old furnace, $400 repair: 15 × $400 = $6,000 → Replace
• 8-year-old furnace, $800 repair: 8 × $800 = $6,400 → Replace (even though it's relatively young, the repair cost is high)

The 50% Rule

If the repair costs more than 50% of what a new furnace would cost, replace. A new mid-efficiency gas furnace installed runs $3,800–$6,200, so any repair over $1,900–$3,100 points toward replacement.

The 15-Year Threshold

Furnaces over 15 years old with any major repair (heat exchanger, blower motor, control board) are generally better candidates for replacement. Parts become harder to find, efficiency drops, and another failure is likely not far behind.

Replacement Cost by Efficiency

The Department of Energy estimates that replacing a furnace over 15 years old can reduce energy consumption by 20–40%. A high-efficiency upgrade typically pays for itself in 5–8 years through lower utility bills.

One important note: federal regulations taking effect in 2028 will require a minimum 95% AFUE for new furnaces in northern states. If you're replacing now, a high-efficiency model avoids potential compliance issues if you sell your home.

Based on data from American Standard and HVAC industry reports, these are the most frequent furnace issues homeowners encounter — and what they cost.

1. Dirty or clogged air filter — $5–$30 (DIY) The single most common cause of furnace problems. A clogged filter restricts airflow, causing the furnace to overheat and short cycle. Change your filter every 1–3 months during heating season. This alone prevents more breakdowns than any other maintenance task.

2. Thermostat issues — $100–$600 Sometimes the problem isn't the furnace at all. Check that your thermostat is set to "heat" and the temperature is set above room temperature. Dead batteries are a surprisingly common culprit. If the thermostat itself needs replacing, expect $100–$600 depending on whether you're upgrading to a smart thermostat.

3. Short cycling — $20–$350 When your furnace turns on and off every few minutes, it's usually a dirty filter ($5–$30), a failing pressure switch ($150–$350), or a bad limit switch ($65–$125). Start by checking the filter before calling a technician.

4. Ignition problems — $75–$400 Modern furnaces use hot surface ignitors or direct spark ignition instead of standing pilot lights. These wear out and need replacement every 5–7 years. Cost: $150–$400 for the ignitor, or $75–$300 if it's just a dirty flame sensor that needs cleaning.

5. Strange noises — $150–$2,500 Banging usually means delayed ignition (gas builds up before igniting). Squealing points to a belt or bearing issue in the blower motor. Rattling often means loose components. Costs range widely depending on the cause.

6. Cracked heat exchanger — $500–$3,500 The most expensive repair and a safety concern. A cracked heat exchanger can leak carbon monoxide into your home. If your furnace is over 15 years old and the heat exchanger cracks, replacement of the entire furnace is almost always recommended.

7. Blower motor failure — $300–$2,500 The blower motor pushes heated air through your ducts. Single-speed (PSC) motors cost $300–$800 to replace. Variable-speed (ECM) motors run $1,500–$2,500. The motor's type is the biggest factor in cost.

8. Dirty flame sensor — $75–$300 The flame sensor detects whether a flame is present. When it gets dirty, it can't sense the flame and shuts the furnace down as a safety precaution. Cleaning costs $75–$150. Replacement costs $100–$300. This is one of the most common service calls HVAC technicians respond to.

9. Tripped circuit breaker — Free (DIY) Before calling a technician, check your electrical panel. A tripped breaker is a free fix. If the breaker trips repeatedly, that's a different issue — likely an electrical problem that needs professional diagnosis.

10. Gas valve problems — $200–$1,500 The gas valve controls fuel flow to the burners. Failure means the furnace can't produce heat. Replacement costs $200–$1,500 depending on the valve type and furnace model. Gas valve work should always be done by a licensed professional.

When to DIY vs. Call a Professional

Safe to DIY:

• Changing the air filter
• Checking and adjusting the thermostat
• Resetting a tripped circuit breaker
• Clearing obstructions from vents and registers
• Checking that the gas valve is in the "on" position

Always call a professional:

• Anything involving gas lines or the gas valve
• Electrical component repairs
• Heat exchanger issues
• Any repair where you smell gas or suspect carbon monoxide
• Blower motor or inducer motor replacement

1. Schedule annual maintenance. A tune-up costs $90–$200 and prevents the majority of breakdowns. According to ASHRAE, 85% of furnace repairs are linked to lack of maintenance. Regular maintenance also extends your furnace's lifespan by up to 50%.

2. Book repairs in spring or summer. HVAC contractors are less busy during off-season months (April–August). You'll get faster service, shorter wait times, and potentially 15–25% lower prices compared to peak heating season.

3. Get 2–3 quotes for non-emergency repairs. Pricing varies significantly between contractors. A blower motor replacement might be quoted at $800 by one company and $1,400 by another. Getting multiple quotes takes minimal effort and can save hundreds.

4. Ask if the diagnostic fee is credited toward the repair. Many HVAC companies charge a $75–$200 diagnostic fee but credit it toward the repair bill if you proceed with the work. Ask about this policy when you call to schedule.

5. Check your warranty before paying. Parts warranties typically last 5–10 years from installation. Heat exchangers often carry lifetime warranties on higher-end models. If your furnace is still under warranty, you may only pay for labor.

6. Consider a maintenance plan. Annual plans cost $150–$500 and typically include two service visits (heating and cooling season), priority scheduling, and 10–20% discounts on repairs. If your furnace is over 10 years old, the priority scheduling alone can be worth it during a winter breakdown.

7. Change your filter regularly. A $5–$30 filter change every 1–3 months is the simplest thing you can do to prevent costly repairs. A dirty filter is the number one cause of furnace problems — and it's the one cause that's entirely within your control.

Stat worth knowing: only 30% of homeowners schedule preventive maintenance, yet it reduces breakdown risk by up to 95%. The $100–$200 you spend on a tune-up is almost always cheaper than the repair it prevents.