The short answer
Furnace repair vs replace comes down to two conditions: replace the furnace only when it is 15 or more years old and the repair quote is 30% or more of the cost of a new furnace, which runs $6,400–$13,300 installed in Clark County at 2026 prices, so the line sits around $2,000–$4,000. If only one condition is true, repair it and keep running. Age alone is not a reason to replace, and neither is a big repair quote alone.
In this guide
The two-condition rule.
Replace your furnace only if both of these are true:
- The system is 15 years or older. By then a furnace is into the back half of its working life, so every repair is buying borrowed time.
- The repair quote is 30% or more of what a replacement would cost. This is the point where fixing it stops making financial sense.
One condition met, or neither: repair. Both met: replace.
Furnace repair vs replacement cost: the numbers to compare.
A new gas furnace installed by our crew in Clark County runs $6,400–$13,300 at 2026 prices, with equipment, labor, permits and commissioning included. Divide your repair quote by the price of the furnace you would actually buy. Our furnace replacement cost guide covers what moves that price.
Repair or replace? Get a straight answer.
Five quick taps. We run our 15-year, 30% rule on your furnace and show you the math. No email needed.
This quiz needs JavaScript. The rule: replace only if the furnace is 15+ years old AND the repair is 30% or more of a new furnace. Otherwise, repair. Questions? Call (360) 838-5568.
How old is your furnace?
Age is the first test. A best guess is fine.
What is the repair quote?
The total you were quoted, parts and labor.
What failed?
Only one answer changes the rule on its own: a cracked heat exchanger.
How efficient is it now?
This decides whether gas prices matter to your answer.
Anything else true?
Pick all that apply. These can change the answer.
How we can help
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Worked examples.
The repair quotes in these examples, and the $8,500 replacement quote each one is divided by, are sample numbers to show the math, not prices from our price list. Put your own quote in their place.
| Furnace | Repair | Share | Call |
|---|---|---|---|
| 18 years old, failed inducer motor | $950 | 11% | Repair |
| 16 years old, cracked heat exchanger | $2,900 | 34% | Replace |
| 8 years old, blown ignition control board | $680 | 8% | Repair |
| 14 years old, failed blower motor | $1,100 | 13% | Repair |
Only the 16-year-old furnace meets both conditions, and a heat exchanger failure at that age means the other wear parts are tired too. The 18-year-old furnace is old, but a single repair at 11% doesn't justify replacement, and the 14-year-old one is just under the age threshold.
A $900 quote on a 15-year-old furnace.
A $900 repair quote on a 15-year-old furnace is 14% of even the cheapest new furnace ($6,400 installed in Clark County). The furnace meets the age condition but not the cost condition. Repair it, and start planning the replacement for a calm month instead of a January emergency.
The repair is half the replacement cost.
If the repair is 50% of a new furnace and the furnace is 15 or older, replace it; you would be spending half the price of a new system on an old one. If the furnace is younger, the rule says repair, but first ask whether the failed part is still under the manufacturer's parts warranty, which can change the quote completely.
How long does a furnace last?
Most gas furnaces last 15 to 20 years, according to Carrier, and the U.S. Department of Energy used an average lifetime of 21.5 years for gas furnaces in its 2023 furnace efficiency rule. So a furnace has no set replacement date: replace it once it is 15 or older and a repair quote reaches 30% of the price of a new furnace.
ENERGY STAR uses the same 15-year mark, listing a furnace more than 15 years old as a reason to consider replacing it, along with frequent repairs and rising energy bills. Where a furnace lands in that 15-to-20-year range comes down to a few things:
- Filters and tune-ups. A dirty filter restricts airflow and makes the blower motor strain. Carrier calls regular filter changes and annual maintenance the two most effective ways to extend a furnace's life.
- Sizing. An oversized furnace turns on and off rapidly, and Carrier says those short cycles add wear and can lead to premature failure. We run a Manual J load calculation on every install so the furnace is sized to the house's actual heating load.
- Summer work. If your central AC blows through the furnace, the blower runs year-round, and Carrier counts that use against the furnace's lifespan.
- The drain on a 95% furnace. High-efficiency furnaces drain condensate, and Carrier warns that improper drainage can cause internal damage.
Dirty or worn out? A furnace that keeps shutting off early is often just choked. Carrier names a clogged filter as a leading cause of short cycling, because trapped heat trips the limit switch, and a faulty flame sensor can also shut it down. Start with our filter guide. A cracked heat exchanger, or frequent repairs past 15 years, is the worn-out kind. Weighing a heat pump instead? See how long heat pumps last in Vancouver.
Do high energy prices change the answer?
High energy prices change the furnace repair-or-replace answer less than most people think. Gas prices only matter through efficiency, which for a furnace is its AFUE rating. Going from an old 80% AFUE furnace to a 95% AFUE furnace cuts the gas you burn for the same heat by about 16% (80 divided by 95). If your old furnace burns $1,800 a year in gas, a 95% unit brings that to roughly $1,520, about $280 a year. To see the payback, divide the extra cost of the 95% furnace on your quote by that yearly saving.
So higher gas prices make the 95% furnace pay back faster once you are replacing anyway. They rarely justify replacing a furnace that only needs a small repair, and if your current furnace is already 90%+ AFUE, energy prices barely move the decision at all. The bigger question at replacement time is often whether to stay on gas or switch to a heat pump (or a dual-fuel hybrid).
When the rule doesn't apply.
Five situations change the 15-year, 30% math:
- Heat exchanger failure. A cracked heat exchanger is a carbon monoxide risk. It is also an expensive repair, and by the time one cracks the other parts are generally tired too. This almost always pushes to replace.
- An AC that still runs on R-22. If the air conditioner paired with your furnace uses R-22 (no longer produced since 2020), a refrigerant leak on the cooling side gets expensive to fix. That often tips the decision toward replacing the furnace and AC together.
- You're moving soon. A buyer cares about HVAC condition. A 16-year-old repaired furnace is a negotiation point. A new system isn't.
- Efficiency upgrade with real payoff. When the payback is short (see the energy-price math above), early replacement can make sense even without a failure.
- Fuel switch on the table. For homes still on oil heat, the oil-to-heat-pump conversion math usually beats a straight oil furnace replacement.
Red flags to watch for.
When a contractor pushes furnace replacement, these are the red flags to listen for:
- "It's not worth fixing", without showing you numbers
- "Parts aren't available anymore", almost always untrue for common residential furnaces
- "We can't warranty a repair on something this old", a shop choice, not a physical limitation
- "The inspector would red-tag it", ask exactly which code violation
- Pressure to sign before the end of the call
One more consideration: timing.
A furnace that dies in January forces a rushed decision. If your furnace is 15+ and limping, planning a September or April replacement (off-peak, with proper permit time) is always better than an emergency replacement in a crisis: repair now, and plan the replacement for a calm month.
Got a repair quote you're unsure about? Get a second opinion from us. We'll tell you honestly whether the math favors keeping your system or replacing it.
Questions homeowners ask.
Should I repair or replace my furnace?
Replace it only if both of these are true: the furnace is 15 years or older, and the repair quote is 30% or more of the cost of a new furnace. If only one is true, repair it. Age alone is not a reason to replace, and a big repair quote on a young furnace is not either.
How much does a new furnace cost compared to repairing an old one?
A new gas furnace installed in Clark County runs $6,400–$13,300 at 2026 prices. Divide your repair quote by the price of the furnace you would buy. Under 30%, or on a furnace younger than 15, repair usually wins. The furnace replacement cost guide covers what moves the price.
Should I repair a 15-year-old furnace with a $900 repair quote?
Usually yes. $900 is about 14% of even the cheapest new furnace ($6,400 installed), so it meets the age condition but not the cost condition. Repair it, and plan the replacement for a calm month rather than waiting for a January breakdown.
My furnace repair quote is half the replacement cost. Which way should I go?
If the furnace is 15 or older, replace it: you would be spending half the price of a new system on an old one. If it is younger, the rule says repair, but first ask whether the failed part is still under the manufacturer's parts warranty, which can change the quote completely.
Do high energy prices mean I should replace my old furnace now?
Only if the efficiency jump is big enough. Going from an 80% to a 95% AFUE furnace cuts gas use by about 16%, roughly $280 a year on an $1,800 annual gas bill. Divide the extra cost of the 95% furnace on your quote by that saving to get the payback in years. If your furnace is already 90%+ AFUE, energy prices barely change the decision. They matter most when you are replacing anyway.
What is the difference between furnace repair and heating system replacement?
A repair replaces one failed part, such as an igniter, inducer motor, control board or blower motor, and keeps the rest of the furnace. A replacement swaps the whole furnace, and often the AC coil and thermostat with it, and needs a mechanical permit. Repairs cost a fraction of replacement, which is why the 30% rule exists.
What are red flags that a contractor is pushing unnecessary furnace replacement?
Watch for 'it's not worth fixing' without any numbers, 'parts aren't available anymore' (almost always untrue for common residential furnaces), 'we can't warranty a repair on something this old' (a shop choice), or 'the inspector would red-tag it' without naming the code violation. Pressure to sign before the end of the call is also a red flag.
When does the repair-vs-replace rule not apply?
A cracked heat exchanger is a carbon monoxide risk and almost always pushes toward replacement. An AC that still runs on R-22 makes cooling-side repairs expensive and often tips the decision toward replacing both. Moving soon, a short efficiency payback, or a planned switch to a heat pump can also change the math.
Sources and resources
Reviewed for accuracy by Sam Tsarenko, founder of Pacific Peak Mechanical. This guide draws on the following primary sources:
- Carrier, How Long Does a Furnace Last?
- Carrier, Understanding Furnace Short Cycling
- ENERGY STAR, When to Replace Heating and Cooling Equipment
- U.S. Dept. of Energy, Energy Conservation Standards for Consumer Furnaces (Federal Register, Dec. 18, 2023), for the 21.5-year average lifetime
Related from Pacific Peak: Furnace repair in Vancouver WA · Furnace installation in Vancouver WA · HVAC repair in Vancouver WA
