Replace your furnace if both of these are true: (1) it's 15+ years old, AND (2) the repair quote is 30% or more of a replacement cost. Only one of those conditions? Repair and keep running. Age alone is not a reason to replace. Big repair quote alone is not a reason to replace.
This is the single most common phone call we take. Furnace stopped working, a contractor came out, and now there's a $1,800 repair quote sitting on the kitchen counter — alongside a $9,500 replacement quote. How do you decide?
Most HVAC shops will push you toward replacement. Their margins are better, the commission is bigger, and the sales pitch is easy: "it's already 12 years old, it's going to fail again soon anyway." That's often true. It's also often a bad reason to replace working equipment.
Here's how we actually think about it.
The two-condition rule.
Replace your furnace only if both of these are true:
- The system is 15 years or older. That's past the midpoint of a typical furnace's 18–25-year service life. You're 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.
Only one of those conditions met? Repair and keep running. Neither of them met? Definitely repair. Both met? Time to replace.
Worked examples.
Example 1: The classic trap.
18-year-old furnace. Inducer motor failed. Repair quote: $950. Replacement quote: $8,500.
$950 is 11% of replacement cost. The system is old, but a single repair at 11% doesn't justify replacement. Repair it. The shop telling you otherwise is quoting their preferences, not your math.
Example 2: Real replacement territory.
16-year-old furnace. Heat exchanger cracked. Repair quote (new heat exchanger + labor): $2,900. Replacement quote: $8,500.
$2,900 is 34% of replacement cost. System is past 15 years. Heat exchanger failure means you're also paying for other wear parts that will fail in the next few years. Replace it.
Example 3: Newer system, big repair.
8-year-old furnace. Blown ignition control board. Repair quote: $680. Replacement quote: $8,500.
The repair is 8% of replacement. The system is young. Absolutely repair. Anyone quoting replacement on an 8-year-old furnace is pushing unnecessary product.
Example 4: Old but reliable.
14-year-old furnace. Blower motor failed. Repair quote: $1,100. Replacement quote: $8,500.
Just under the age threshold. Repair is 13% of replacement. Repair it. That blower motor will run another 8–10 years — you've bought a real extension, not just patched the symptom.
When the rule doesn't apply.
A few situations where the math changes:
- Heat exchanger failure. A cracked heat exchanger means carbon monoxide risk. Repair cost is usually 35%+ of replacement on its own, and by the time a heat exchanger fails other parts are generally tired too. This almost always pushes to replace.
- R22 refrigerant in the AC side. If your furnace and AC share a refrigerant system running R22 (phased out in 2020), any refrigerant repair is prohibitively expensive. That changes the replacement math on both units.
- You're moving soon. A buyer in Vancouver's current market cares about HVAC condition. A 16-year-old repaired furnace is a negotiation point. A new system isn't.
- Efficiency upgrade with real payoff. If your 18-year-old 80% AFUE furnace costs you $1,800/year in gas, a new 95% AFUE unit cuts that to $1,520. That's $280/year forever. At a $2,000 premium over an 80% replacement, it pays back in 7 years. Different math than a simple repair decision.
Red flags to watch for.
When a contractor pushes replacement, listen for these:
- "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
Our promise on diagnostics
When we diagnose a system and the repair math favors keeping it, we'll tell you. On a system where replacement is the right call, we'll walk you through why — in writing, with numbers. You'll never be pressured to sign during a service call.
One more consideration: timing.
A system that dies in August (AC) or January (heat) 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 emergency replacement in a crisis. We'll help you triage: repair now, plan for replacement in six months.
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. No sales pressure — just the numbers.