Should you repair or replace your furnace?
Short answer: Repair if the furnace is under about 15 years old and the fix is a common part like an igniter, flame sensor, or control board. Lean toward replacing if it's 15 to 20 years old, needs an expensive part like a heat exchanger, keeps breaking every winter, or has a safety problem. Angi puts the average furnace life at about 20 years.
Four questions that decide it
1. How old is it? Find the install date on the label inside the door or ask your HVAC company. Angi says furnaces last about 20 years on average.
2. What does the repair cost compared to a new furnace? Most repairs are $133 to $505 (Angi, 2026). A new gas furnace is $3,800 to $10,000. A common rule of thumb: multiply the furnace's age by the repair cost. If the result is over about $5,000, replacing usually makes more sense. Treat it as a starting point, not a law.
3. Is it a safety issue? A cracked heat exchanger can leak carbon monoxide. On an older furnace that's almost always a replace decision. Ask the tech to show you the crack or camera image.
4. How often has it failed? Two or three repair calls in the last couple of winters is a sign more are coming. If the same symptom keeps coming back, like a furnace blowing cold air, ask the tech what’s actually failing.
Reasons to replace even if it still runs
- It's an older, lower-efficiency unit and your gas bills are high.
- Rooms are uneven or it's noisy, and a variable-speed blower would fix that.
- You qualify for a rebate. In Utah, Enbridge Gas's ThermWise pays $300 to $350 for a qualifying high-efficiency gas furnace in 2026. (The federal tax credit ended for installs after December 31, 2025.)
Reasons to repair
- It's under about 10 to 12 years old and the part is common.
- The part is still under warranty.
- You're selling the house soon and the furnace passes inspection.
Get a second opinion when
Someone tells you a heat exchanger is cracked, or quotes a replacement on the first visit without showing you why. A second tech visit costs far less than an unneeded furnace.
FAQ
Should I replace my AC at the same time? If the AC is also old, doing both together can save labor and makes sure the blower and coil match. If the AC is newer, you can usually replace only the furnace.
Do I need a bigger furnace? Not necessarily. Many old furnaces are oversized. Ask for a load calculation.
Related: Furnace replacement cost · Furnace repair cost · Buying a furnace in Utah
Sources: Angi new furnace cost, 2026 · Angi furnace repair cost, 2026 · Enbridge Gas ThermWise · 26 USC 25C
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