Furnace Repair Cost Calculator
Furnace Repair costs $190 to $290 for a typical 2,000 sq ft job in 2026, against a national benchmark of $235. Labor runs 1.2 crew hours at $42.44 an hour. Enter a ZIP code to apply that area's measured wages for this work and its regional price level.
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What makes up the price
Cost by size
National averages, before any local adjustment. Computed from the same model as the calculator above, so the two always agree.
| Home size | Thousand BTU | Typical | Range |
|---|---|---|---|
| 1,100 sq ft | 40 | $220 | $180 to $275 |
| 1,600 sq ft | 60 | $225 | $185 to $280 |
| 2,000 sq ft | 80 | $235 | $190 to $290 |
| 2,700 sq ft | 110 | $245 | $200 to $305 |
| 3,400 sq ft | 140 | $255 | $210 to $315 |
Check four things before you call
Each takes a minute and each is a reason a furnace is not running that is not a repair.
- The filter. A blocked filter overheats the furnace, which trips the high-limit switch, which shuts it down. A furnace that runs briefly and stops, over and over, is very often this.
- The switch on the side. Furnaces have a light-switch-looking service switch on or near the cabinet. It gets turned off by accident more often than anyone admits.
- The thermostat. Batteries, and that it is set to heat rather than to a schedule that thinks it is still summer.
- The breaker, and on a gas furnace, that the gas is on — if the water heater and stove still work, it is not that.
If the furnace tries and fails rather than doing nothing, note how it fails before you call. It is genuinely useful diagnostic information:
- Inducer runs, a click, then nothing, three times, then it gives up — usually the igniter.
- Flame lights and goes out after a few seconds — usually the flame sensor, which is cheaper still.
- Burners light but no air moves — blower motor or capacitor.
- Igniter glows, no flame at all — gas valve, or the gas supply.
What the repairs cost
On an 80,000 BTU furnace:
| Typical | What it is | |
|---|---|---|
| Igniter or flame sensor | $235 | The most common failure |
| Control board | $500 | Erratic behavior, or nothing |
| Gas valve | $525 | Igniter glows but no flame |
| Blower motor | $775 | Burners light, no air moves |
| Cracked heat exchanger | $1,850 | See below |
The igniter is a $50 part. Most of that $235 is the diagnostic and the visit, which is why it is worth knowing the symptom before the technician arrives — it does not change the price, but it tells you whether the quote matches the fault.
The cracked heat exchanger, in both directions
This needs saying carefully, because the two halves of it point opposite ways.
It is a real hazard. The heat exchanger is the metal wall between the burner flame and the air blown into your house. A crack lets combustion gases — including carbon monoxide — into the supply air. That is not a comfort problem, and a technician who finds one is required to red-tag the furnace and shut it off.
And it is the most abused diagnosis in the trade. It is invisible to the homeowner, it cannot be checked after the fact, and it sells a furnace. Some of the time it is called without being found.
So: take it seriously, and ask for evidence.
- Ask to see it. A borescope photograph or video of the crack. Most technicians carry an inspection camera and a genuine finding is easy to show.
- Ask for the CO reading in the supply air, taken with a combustion analyzer, and the number.
- Ask what else could explain the symptom. A flame that rolls or lifts when the blower starts is the classic indirect evidence, and it has other causes.
- Get a second opinion before buying a furnace, from a company that does not know what the first one said. If the first diagnosis was right, the second will find it too, and you have lost a day.
Meanwhile: do not run it, and make sure you have working carbon monoxide detectors on every level. If you do not have CO detectors, buy them today regardless of what is wrong with the furnace. They are $25 and the failure mode of this appliance is the one that does not wake you up.
Repair or replace
A new furnace, using this site's own installation calculator, is around $3,050 for a standard-efficiency 80,000 BTU unit in existing ductwork, or $4,800 for a high-efficiency condensing furnace.
Against that:
- Any repair under about $500 on a furnace under fifteen years old: repair it. Even $775 for a blower is a quarter of a replacement and buys years.
- A cracked heat exchanger at $1,850: replace. That is 60% of a new standard furnace, spent on the oldest part of an old one, and the rest of the furnace is the same age.
- Over fifteen years old and the repair is over about $800: replace. Not because the arithmetic quite says so, but because the next failure is coming and the parts are being discontinued.
The widely quoted $5,000 rule is a reasonable shorthand: multiply the furnace's age by the repair cost, and if it exceeds $5,000, replace. A fifteen-year-old furnace with a $400 repair gives $6,000, which says replace — a little aggressive, but it is pointing the right way.
One real argument for replacing earlier than the arithmetic suggests: a furnace at the end of its life fails in January, and a January replacement is chosen in an afternoon under pressure rather than priced properly in September.
Age, parts and the cold week
Furnace age matters through parts availability more than efficiency. Past about fifteen years, control boards and heat exchangers start being discontinued, and sourcing one takes days — which the household spends cold. That is often what actually settles repair against replace, whatever the numbers say.
The age is on the rating plate inside the furnace door, and the serial number encodes the manufacture date. Worth reading now rather than on the night it fails, along with the model number and the input BTU rating.
What prevents most of this
- Change the filter, every one to three months. More furnace failures trace back to airflow than to anything else, because restricted airflow overheats the heat exchanger — which is also how exchangers crack.
- Keep the area around it clear. A furnace in a closet needs combustion air; boxes stacked against it starve the burner.
- Clean the flame sensor once a year with fine abrasive cloth. It is a five-minute job that prevents the second most common failure on this page.
- Have a fall tune-up if it includes a combustion analysis and a draft check. If it is a filter change and a sticker, it is not worth paying for.
- Keep the condensate drain clear on a high-efficiency furnace — a blocked drain trips a pressure switch and shuts it down, and it is the most common nuisance fault on a condensing unit.
Questions worth asking
- What is the diagnostic fee, and is it credited against the repair?
- What fault code did it show, and what does it mean?
- Is the part under warranty? Most furnaces carry 5 to 10 years on parts, often 20 or lifetime on the heat exchanger specifically — and that is commonly forgotten. Have the model and serial ready.
- If a cracked heat exchanger: can you show me? And what was the CO reading?
- What does a replacement cost, from you, if this repair is over $800?
- Was the manifold pressure checked after a gas valve replacement? It should be set with a manometer, not assumed.
Common questions
How much does furnace repair cost?
Most repairs fall between $235 and $775 on an 80,000 BTU furnace. An igniter or flame sensor is about $235, a control board $500, a gas valve $525 and a blower motor $775. A cracked heat exchanger is around $1,850. The diagnostic visit itself is $75 to $200 and is usually credited against the repair.
What is the most common furnace repair?
The hot surface igniter, with the flame sensor close behind — and both are cheap parts, around $50, fitted for about $235 once the diagnostic is counted. The classic igniter symptom is a furnace that tries three times and locks out: the inducer starts, there is a click, then nothing. A flame that lights and goes out after a few seconds is usually the flame sensor instead.
What should I check before calling for furnace repair?
Four things, a minute each. The filter, because a blocked one overheats the furnace and trips the high-limit switch — a furnace that runs briefly and stops repeatedly is often just this. The service switch on the side of the cabinet, which looks like a light switch and gets knocked off. The thermostat, meaning batteries and that it is set to heat. And the breaker, plus the gas supply if nothing else gas-fired is working.
How do I know if my heat exchanger is really cracked?
Ask to see it. Most technicians carry a borescope, and a genuine crack is straightforward to photograph — so ask for the image. Ask for the carbon monoxide reading in the supply air, taken with a combustion analyzer, and the actual number. Then get a second opinion from a company that does not know what the first said, before buying a furnace. Take the diagnosis seriously in the meantime: do not run the furnace, and make sure you have working CO detectors on every level.
Is a cracked heat exchanger dangerous?
Yes. The heat exchanger is the metal wall between the burner flame and the air blown into the house, so a crack lets combustion gases including carbon monoxide into the supply air. A technician who finds one is required to red-tag the furnace and shut it off, and that is the correct response rather than an upsell tactic. It is also the most frequently claimed diagnosis in the trade without being found, which is why asking for evidence and a second opinion is reasonable rather than paranoid.
Should I repair or replace my furnace?
A new standard-efficiency furnace in existing ductwork is around $3,050, or $4,800 for a high-efficiency condensing unit. Against that: repair anything under about $500 on a furnace under fifteen years old, and even $775 for a blower is a quarter of a replacement. Replace on a cracked heat exchanger, which at $1,850 is 60% of a new furnace spent on the oldest part of an old one. Over fifteen years with a repair over about $800, replace — because the next failure is coming and the parts are being discontinued.
What is the $5,000 rule for furnaces?
Multiply the furnace's age in years by the cost of the repair, and if the result exceeds $5,000, replace it rather than repairing it. A fifteen-year-old furnace with a $400 repair gives $6,000, so the rule says replace. It is a little aggressive and it is pointing the right way — the useful thing about it is that it weights age properly, which people tend not to do when they are looking at a single repair bill in isolation.
Why does furnace age matter so much?
Through parts availability more than efficiency. Past about fifteen years, control boards and heat exchangers start being discontinued, and sourcing one takes days that the household spends cold — which often settles repair against replace regardless of the arithmetic. The age is on the rating plate inside the furnace door and encoded in the serial number, and it is worth reading now rather than on the night it fails.
Why does my furnace keep shutting off after a few minutes?
Almost always restricted airflow. The furnace overheats, the high-limit switch does its job and shuts it down, it cools, and it starts again — which is called short cycling. The first suspect is the filter, then closed or blocked supply registers, then a dirty blower wheel. It is worth fixing promptly rather than living with: repeated overheating is one of the ways a heat exchanger cracks.
How much is an after-hours furnace call?
About a third more, which on a $235 igniter repair is $350. Furnaces fail on the coldest night because that is the night they run hardest, and that is also when every technician is already out. If the house will hold temperature overnight, waiting until a normal appointment saves real money. If there is a freezing risk to the pipes, or anybody vulnerable in the house, it is not a decision about money.
Is my furnace still under warranty?
Quite possibly, and it is routinely forgotten by both sides. Most furnaces carry five to ten years on parts, and many carry twenty years or a lifetime on the heat exchanger specifically — which is the one part where it matters most. The warranty covers the part and usually not the labor, but on a heat exchanger that is the difference between $1,850 and a few hundred dollars of labor. Have the model and serial number off the rating plate ready when you call.
What furnace maintenance actually matters?
Change the filter every one to three months — more failures trace back to airflow than to anything else, and restricted airflow is also how heat exchangers crack. Clean the flame sensor once a year with fine abrasive cloth, which is a five-minute job that prevents the second most common failure. Keep the area around the furnace clear so the burner has combustion air. And on a high-efficiency furnace keep the condensate drain clear, since a blocked drain trips a pressure switch and is the most common nuisance shutdown.
Where these numbers come from
Nothing here is copied from a contractor directory. Labor is priced from what the trades are actually paid, materials from published producer prices, and both are adjusted to your area using federal cost-of-living data.
- Plumbing, heating and air-conditioning contractors, United States: $42.44/hour, August 2026 (BLS CES CES2023822003)
- Hot surface igniter or flame sensor: $50.00 per part (price recorded October 2026, not index-adjusted)