Furnace Repair Cost Calculator

In 2026, furnace repair typically costs $150 to $700, with most repairs averaging around $300. The cost depends heavily on what's broken: a thermostat replacement runs $150-$350, an igniter or flame sensor $150-$400 (common no-heat causes), a blower motor or capacitor $300-$700, a control board or gas valve $400-$900, and a heat exchanger $1,000-$2,000+ (a major, safety-critical repair). A basic service call/diagnostic fee is often $75-$150 (sometimes waived if you proceed with the repair). The cost depends mainly on the repair type (the failed part — a thermostat or igniter is cheap, a heat exchanger is expensive), the fuel type (an electric furnace is simplest/cheapest to repair, gas is the baseline, propane similar, and oil the most complex), the complexity (a minor/quick fix vs an old furnace with hard-to-find parts), and the service timing (standard hours vs after-hours, weekend, or emergency service, which carry premiums). A furnace repair fixes a malfunctioning furnace — diagnosing the problem (a technician inspects and tests to find the cause) and replacing/repairing the faulty component. Common furnace problems include: no heat (igniter, flame sensor, thermostat, gas valve, or pilot issues), the furnace not turning on (thermostat, control board, power), short-cycling (overheating, flame sensor, airflow), a blower not working (blower motor, capacitor, belt), strange noises (blower, bearings, ignition), and weak/uneven heat (airflow, ducts, undersizing). The technician diagnoses and repairs the specific issue. Note: for an old furnace (15-20+ years) with a major or costly repair (like a heat exchanger), replacing the furnace may be more economical than repairing it (the '50% rule' — if the repair exceeds ~50% of a new furnace's cost, consider replacing). Add-ons like the diagnostic/service-call fee, a full tune-up/maintenance, duct cleaning, a carbon monoxide test, a filter replacement, and a repair warranty add to the total. Pricing varies by region, the repair, the part, the fuel, and the company. A simple igniter or thermostat fix is at the lower end, while a heat exchanger, control board, or emergency repair is at the higher end. This calculator lets you set the repair type, fuel type, complexity, and service timing to estimate your project.

The most common furnace problems include no heat, the furnace not turning on, short-cycling, a malfunctioning blower, strange noises, and weak or uneven heat — caused by issues like a faulty igniter or flame sensor, a bad thermostat, a worn blower motor or capacitor, a dirty filter, or a failing control board. Most are repairable, and many are inexpensive. Common problems and their typical causes/repairs: No heat — the furnace runs but doesn't heat (or won't ignite). Common causes: a faulty igniter (the hot-surface igniter fails — a very common, inexpensive repair) or flame sensor (a dirty/failed flame sensor shuts down the burner — cheap to clean/replace), a thermostat problem, a gas valve/supply issue, a pilot light issue (older furnaces), or a tripped safety. The igniter and flame sensor are the most common no-heat culprits (and affordable fixes). Furnace won't turn on — no response. Causes: a thermostat issue (dead batteries, settings, wiring), a power problem (tripped breaker, blown fuse, a switch off), a control board failure, a clogged condensate line (high-efficiency furnaces — a safety switch shuts it off), or a safety lockout. Short-cycling — the furnace turns on and off frequently. Causes: overheating (a dirty filter restricting airflow — a common, simple fix; or a blocked vent), a dirty flame sensor, an oversized furnace, or a thermostat issue. Often a dirty filter or flame sensor. Blower not working / weak airflow — the fan doesn't run or airflow is weak. Causes: a failed blower motor or capacitor, a bad belt (older units), a control issue, or a dirty filter. Blower motor/capacitor repairs are common. Strange noises — banging, squealing, rattling, grinding. Causes: ignition issues (banging on startup — delayed ignition), blower problems (squealing belt, worn bearings), loose parts (rattling), or motor issues (grinding). Noises indicate specific component problems. Weak or uneven heat — insufficient or uneven heating. Causes: a dirty filter, airflow/duct issues, a failing component, or an undersized furnace. Cold air / wrong temperature — blowing cold air. Causes: thermostat settings (fan 'on' vs 'auto'), ignition issues, or overheating shutoff. Yellow flame / soot — a yellow (vs blue) burner flame or soot indicates incomplete combustion (a problem and potential carbon monoxide risk — needs prompt attention). Frequent/most affordable repairs: igniter, flame sensor (clean/replace), thermostat, capacitor, and filter (the dirty filter is the simplest, and prevention) — these common repairs are relatively inexpensive. More costly: blower motor, control board, gas valve, and heat exchanger. Prevention: many problems (short-cycling, weak heat, overheating) stem from a dirty filter or lack of maintenance — regular filter changes and annual tune-ups prevent many issues. Considerations: most furnace problems (no heat, won't start, short-cycling, blower, noises) have identifiable causes (igniter, flame sensor, thermostat, capacitor, filter, control board) — a technician diagnoses the specific issue. Many common repairs are affordable; major ones (heat exchanger) are costly (and may favor replacement for old furnaces). This calculator includes common repair types. So the most common furnace problems are no heat, won't turn on, short-cycling, blower issues, strange noises, and weak heat — often caused by the igniter, flame sensor, thermostat, capacitor, dirty filter, or control board (many affordable to fix). A technician diagnoses the cause. Regular maintenance prevents many issues. Most furnace repairs are routine and fixable.

Whether to repair or replace your furnace depends on its age, the repair cost, the furnace's condition/efficiency, and repair frequency — a common guideline is to replace if the furnace is old (15-20+ years) and/or the repair cost exceeds ~50% of a new furnace's cost (the '50% rule'), while repairing makes sense for newer furnaces with affordable, occasional repairs. Weigh the factors. When to REPAIR (repair makes sense): Newer furnace — if the furnace is relatively new (under ~10-12 years, well within its 15-20 year lifespan), repairing is usually worth it (the furnace has years of life left). Affordable repair — if the repair is inexpensive (igniter, flame sensor, thermostat, capacitor — common, cheap fixes), repairing is cost-effective. Infrequent repairs — if the furnace has been reliable (this is a one-off repair), fix it. Good condition/efficiency — if the furnace is otherwise in good shape and reasonably efficient. For a newer, reliable furnace with an affordable repair, repair it. When to REPLACE (replacement makes sense): Old furnace — if the furnace is near or past its lifespan (15-20+ years for gas), replacing is often wiser (it's nearing the end anyway, and will likely need more repairs). Age is a key factor. Expensive repair (50% rule) — if the repair cost exceeds ~50% of a new furnace's cost (e.g., a $1,500+ heat exchanger or control board on an old furnace), replacing is often more economical than pouring money into an old unit. The '50% rule' (or the '5,000 rule': multiply the repair cost by the furnace's age — if over $5,000, consider replacing). Heat exchanger failure — a cracked heat exchanger (a major, safety-critical, costly repair, and a carbon monoxide risk) on an older furnace usually means replacement. Frequent repairs — if the furnace needs frequent/recurring repairs (nickel-and-diming you), replacing ends the cycle. Rising energy bills / low efficiency — an old, inefficient furnace (especially below 80% AFUE) costs more to run; a new high-efficiency furnace saves on energy (offsetting the replacement cost over time). Safety concerns — carbon monoxide issues, a cracked heat exchanger, or unsafe operation warrant replacement. Comfort issues — if the furnace can't keep the home comfortable. The decision factors: Age — older = lean toward replace. Repair cost vs furnace value — expensive repair on an old furnace = replace (50% rule). Frequency — frequent repairs = replace. Efficiency — old/inefficient = replacing saves energy. Safety — safety issues = replace. Long-term plans — staying long-term favors investing in a new efficient furnace; selling soon might favor a repair. Considerations: repair a newer furnace with an affordable, occasional repair; replace an old furnace (15-20+ years), one needing an expensive repair (over ~50% of replacement cost), one with a cracked heat exchanger or safety issues, or one needing frequent repairs or running inefficiently. An HVAC technician can assess and advise (and provide both repair and replacement quotes). This calculator estimates repair cost (see the furnace installation calculator for replacement). So repair your furnace if it's newer with an affordable, infrequent repair, and replace it if it's old (15-20+ years), needs an expensive repair (50% rule), has a cracked heat exchanger or safety issues, needs frequent repairs, or runs inefficiently. Weigh age, repair cost, frequency, efficiency, and safety. Get a pro's assessment. The 50% rule and age are the key guides.

You can safely DIY some basic furnace troubleshooting and simple fixes (checking the thermostat, replacing the filter, resetting the breaker, cleaning the flame sensor), but most furnace repairs — especially those involving gas, electrical components, or the combustion system — should be done by a qualified HVAC technician for safety and proper repair. The repair type and safety risks determine whether DIY is appropriate. DIY-friendly (basic troubleshooting/fixes): Check the thermostat — ensure it's set to 'heat,' the temperature is set correctly, and the batteries are fresh (a common, simple fix). Replace the air filter — a dirty filter causes many problems (short-cycling, weak heat, overheating); replacing it is easy DIY and often resolves issues (and is key maintenance). Check the power — ensure the furnace switch is on, and check/reset the breaker or fuse (if tripped). Check the furnace door — some furnaces won't run if the access panel/door isn't properly closed (a safety switch). Clean the flame sensor — a dirty flame sensor (causing the furnace to start then shut off) can sometimes be cleaned by a careful DIYer (removing and gently cleaning it) — though this involves accessing the burner area. Relight a pilot light — for older furnaces with a standing pilot, relighting it (per instructions). Clear the condensate line — for high-efficiency furnaces, a clogged condensate line can be cleared. Keep vents clear — ensure registers/vents aren't blocked. These basic steps can resolve simple issues (and are worth checking before calling a pro). When to hire a technician: Gas components — anything involving the gas valve, gas line, burners, or gas supply should be done by a professional (gas leaks, explosions, carbon monoxide risks — serious safety hazards). Don't DIY gas repairs. Electrical components — the control board, blower motor, capacitor, wiring, and electrical repairs require expertise (shock risk, proper diagnosis). Igniter replacement — while some DIY it, proper replacement/handling matters. Heat exchanger — a cracked heat exchanger (carbon monoxide risk) is a serious, professional repair (or replacement). Combustion/venting — combustion issues, venting, and carbon monoxide concerns require a professional (safety-critical). Diagnosis — if you can't identify the problem, a technician diagnoses it properly (avoiding misdiagnosis and wasted parts). Persistent/complex problems — recurring or complex issues. Safety/uncertainty — when in doubt, or for any safety concern (gas smell, CO, soot, unusual operation), call a professional. Why hire a pro: furnaces involve gas (explosion, CO risks), electrical (shock), and combustion (safety) — professional technicians safely and correctly diagnose and repair issues, ensuring safe operation (avoiding gas leaks, carbon monoxide, fire, and electrical hazards). Given the safety stakes, most repairs warrant a pro. Considerations: DIY basic troubleshooting and simple fixes (thermostat, filter, breaker, flame sensor cleaning, pilot light) — these resolve many issues and are worth checking first; but hire a qualified HVAC technician for gas, electrical, combustion, heat exchanger, or any repair you're unsure about (for safety and proper repair). If you smell gas or suspect carbon monoxide, leave and call a professional immediately. This calculator estimates professional repair. So you can DIY basic furnace troubleshooting (thermostat, filter, breaker, flame sensor, pilot light), but hire an HVAC technician for gas, electrical, combustion, heat exchanger, or complex/uncertain repairs — for safety (gas/CO/electrical risks) and proper repair. Check the simple things first; call a pro for the rest. Safety is paramount with furnaces. When in doubt, call a professional.

A furnace blowing cold air or not heating can be caused by several issues — from simple ones (thermostat settings, a dirty filter, a tripped breaker) to component failures (igniter, flame sensor, gas valve, pilot light) — many of which are common and repairable. Here are the typical causes. Simple/check-first causes: Thermostat settings — the thermostat fan set to 'ON' (instead of 'AUTO') makes the fan blow continuously, including cold air when not heating; set it to 'AUTO.' Also check it's set to 'heat' and the temperature is above the room temp. A common, simple fix. Dirty air filter — a clogged filter restricts airflow, causing overheating and the furnace to shut off the burner (blowing cool air) — replace the filter. Power/breaker — a tripped breaker or blown fuse, or the furnace switch off, can stop heating. Furnace door/panel — if the access panel isn't fully closed (a safety switch), the furnace won't fire. No-heat component causes: Faulty igniter — the hot-surface igniter (which ignites the gas) fails (a very common cause of no heat) — the furnace tries but won't ignite. A common, affordable repair. Dirty/failed flame sensor — the flame sensor detects the flame; if dirty or failed, it shuts off the gas (the furnace ignites then quickly shuts off — short-cycling or no heat). Cleaning/replacing it is a common fix. Pilot light out (older furnaces) — for furnaces with a standing pilot, the pilot light going out means no heat (relight it; if it won't stay lit, the thermocouple may be bad). Gas supply/valve — a gas supply issue (gas off, valve problem) prevents ignition. Ignition/control issues — the ignition system or control board failing. Overheating shutoff — the furnace overheating (dirty filter, blocked airflow) triggers a safety limit switch that shuts off the burner (the blower may run, blowing cool air) — addressing airflow resolves it. Condensate clog (high-efficiency) — a clogged condensate line trips a safety switch, stopping the furnace. Other: a tripped safety/limit switch, a thermostat wiring issue, or a control board problem. What to check (DIY first): set the thermostat to 'heat,' fan to 'AUTO,' temp up; replace the filter; check the breaker/switch and furnace door; and (for older units) check the pilot light. These resolve many cases. If those don't fix it: the cause is likely a component (igniter, flame sensor, gas valve, control board) needing a technician to diagnose and repair. The igniter and flame sensor are the most common (and affordable) culprits. Safety note: if you smell gas, leave and call the gas company/professional. A yellow flame or soot (incomplete combustion) needs prompt professional attention (carbon monoxide risk). Considerations: a furnace blowing cold air or not heating is often a simple fix (thermostat set to 'AUTO'/'heat,' filter, breaker, door) — check these first; if not, it's likely the igniter, flame sensor, pilot, gas valve, or control board (needing a technician). Many causes are common and repairable. This calculator estimates repair cost. So a furnace blowing cold air or not heating can be from thermostat settings (fan 'ON'), a dirty filter, a tripped breaker, or component issues (igniter, flame sensor, pilot, gas valve) — check the simple things first, then call a technician for component repairs. The igniter and flame sensor are common, affordable culprits. Address it promptly (especially any gas/CO concern). Most no-heat issues are fixable.

You can avoid many expensive furnace repairs through regular maintenance — annual professional tune-ups, frequent filter changes, keeping the area clear, prompt attention to small issues, and proper operation — which keeps the furnace running efficiently, catches problems early, and extends its life. Preventive care is far cheaper than major repairs. Key prevention measures: Annual professional tune-up/maintenance — have an HVAC technician service the furnace annually (ideally before the heating season): they inspect, clean, and test the furnace (burners, igniter, flame sensor, heat exchanger, blower, electrical, gas pressure, venting, safety controls), catching small issues before they become major (and costly) failures, ensuring safe/efficient operation, and maintaining the warranty. Annual tune-ups (often $100-$150) prevent expensive breakdowns — the best prevention. Change the air filter regularly — replace the filter every 1-3 months (more often with pets, dust, or heavy use). A dirty filter is a leading cause of furnace problems (restricted airflow causes overheating, short-cycling, blower strain, weak heat, and even component failure) — and changing it is cheap and easy. Regular filter changes prevent many issues. Keep the furnace area clear — keep the area around the furnace clean and clear (no clutter, dust, or combustibles), and ensure vents/registers and intakes aren't blocked (for proper airflow). Address small issues promptly — don't ignore warning signs (strange noises, weak heat, short-cycling, frequent cycling, unusual smells, rising bills) — addressing small problems early prevents them from cascading into major (expensive) failures. Catch problems early. Keep vents/registers open and unblocked — for proper airflow (blocked vents strain the system). Test and maintain the thermostat — ensure it works (fresh batteries, proper operation). Keep the condensate line clear (high-efficiency) — prevent clogs that trigger shutoffs. Monitor carbon monoxide — have working CO detectors (safety). Proper operation — don't overwork the furnace (reasonable thermostat settings), and seal/insulate the home (reducing the heating load and furnace strain). Why prevention saves money: Catches issues early — maintenance finds small problems (a worn part, a dirty component) before they cause a major failure (e.g., a dirty filter straining the blower until the motor fails) — fixing small is cheaper than major. Extends lifespan — a well-maintained furnace lasts longer (delaying replacement). Efficiency — a clean, tuned furnace runs efficiently (lower energy bills). Prevents breakdowns — reducing emergency repairs (which carry premiums) and no-heat situations. Safety — maintenance ensures safe operation (no CO/gas issues). The modest cost of maintenance (tune-ups, filters) prevents costly repairs and breakdowns. Considerations: avoid expensive furnace repairs with annual professional tune-ups, regular filter changes (every 1-3 months), keeping the area/vents clear, addressing small issues promptly, and proper operation — preventive maintenance is far cheaper than major repairs or breakdowns, and extends the furnace's life. A maintenance plan (some companies offer them) can help. This calculator includes a tune-up add-on. So avoid expensive furnace repairs through regular maintenance — annual tune-ups, frequent filter changes, keeping the area/vents clear, prompt attention to small issues, and proper operation — keeping the furnace efficient, catching problems early, and extending its life. Prevention is much cheaper than major repairs. Invest in annual maintenance and filter changes. Proactive care saves money and prevents winter breakdowns.