Furnace Replacement: Cost, Efficiency and When to Replace
🇩🇪 Diesen Artikel auf Deutsch lesenReplacing a gas furnace typically costs a few thousand dollars installed, more for high-efficiency condensing models or complex ductwork. Consider replacement if your furnace is over 15–20 years old, needs frequent repairs or your heating bills keep rising. Before buying, compare a high-efficiency furnace with a heat pump using your local energy prices.
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Furnaces rarely fail at a convenient time. Knowing the warning signs and options in advance helps you avoid a rushed, expensive decision in the middle of winter.
Signs it's time to replace
- Age over 15–20 years
- Repairs every season, or a single repair costing a large share of a new unit
- Uneven heating and rising energy bills
- Yellow burner flames, soot or a cracked heat exchanger (a safety issue — call a technician)
Efficiency ratings explained
| AFUE rating | Meaning |
|---|---|
| 80% | Standard efficiency; 20% of fuel energy is lost through the flue |
| 90–98% | Condensing furnace; much less energy wasted, needs PVC venting and a condensate drain |
In cold climates, a high-efficiency furnace usually pays off over its lifetime. In mild climates, the savings may be smaller.
Furnace or heat pump?
If you also need a new air conditioner, a heat pump can replace both systems. Compare running costs with your own energy prices:
Heat Pump vs. Gas Furnace Cost CalculatorCompare yearly running costs side by sideTry the calculator →Getting fair quotes
- Ask for a load calculation (Manual J) rather than matching the old unit's size.
- Compare equipment model numbers, warranty terms and what's included (permits, removal, thermostat).
- Ask about utility rebates for high-efficiency furnaces or heat pumps.
Frequently asked questions
Should I repair or replace an old furnace?
A common rule: if the repair costs more than about a third of a new furnace and the unit is older than 15 years, replacement is often the better investment.
How long does installation take?
A straightforward replacement often takes one day; changes to venting, gas lines or ductwork can take longer.