In short

Multiply the repair cost by the system age — if it tops roughly $5,000, replacement usually wins. Furnaces last 15 to 20 years here, so under 12 years old almost always means repair, over 18 with a major failure usually means replace. Anything in between is a real conversation.

The five-thousand rule

Take the repair quote, multiply it by the age of the system in years. Over $5,000, replacement usually makes more sense:

  • $400 igniter on a 9-year-old furnace → $3,600 — repair it
  • $900 blower motor on a 17-year-old furnace → $15,300 — that money is better spent on the new unit

It is a guideline, not gospel — but it keeps the conversation honest on both sides.

How long furnaces actually last

Gas furnaces run about 15 to 20 years with maintenance; oil furnaces similar. The units we see die early are almost always the ones that skipped service — see the math on skipped maintenance. A well-kept furnace at 15 years is middle-aged, not ancient.

Repairs that almost always make sense

  • Igniters, flame sensors, thermocouples — cheap parts, common failures
  • Capacitors and small electrical parts
  • Thermostat and control issues
  • Most things under 10 years old, period

Where replacement starts winning

  • Cracked heat exchanger — the one failure that is a carbon-monoxide risk, not just a comfort issue. On an older unit, this is replacement, full stop.
  • Repeated breakdowns — two-plus service calls a season is a pattern, not bad luck
  • Rising fuel bills — an old burner running at 65% efficiency while a new one runs 95% is real money every January
  • 18+ years with a major failure — you are paying for the repair now and the replacement soon anyway

Questions to ask whoever quotes you

What exactly failed, and what does the part cost? What is the system’s repair history? What does a new system actually buy me in efficiency? Anyone who cannot answer those without reaching for the replacement brochure is selling, not advising.

Got a replacement quote and want a second opinion?

We give you both numbers with the reasoning — repair and replace — and the decision stays yours. Call or text (267) 227-8115.