Furnace repair vs replace
Repair it, or replace it?
Use your own repair quote, replacement quote and heating costs to compare both paths over time. This is a financial screening tool, not an HVAC diagnosis.
Your numbers
Your result
- Estimated annual fuel saving
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- Estimated heating spend after replacement
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- Simple payback from fuel savings alone
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How this estimate works
The calculator estimates useful heat delivered by your current furnace from your annual heating spend and AFUE, then estimates the fuel cost required to deliver the same heat with the replacement efficiency. The repair path includes the repair quote, your current heating spend and any additional repairs you expect. The replacement path includes the installed quote plus the estimated lower heating spend.
It does not account for financing, maintenance plans, energy-price changes, rebates, differences in equipment capacity, electricity used by blowers, or unexpected failures.
Use it well
Run more than one scenario.
Start with real repair and replacement quotes. Then change the future-repair allowance and comparison period to see how sensitive the result is.
Not just cost
Some decisions are not financial.
Safety, equipment condition, reliability, comfort, capacity, venting, warranty and installation quality can matter more than the lower modeled cost. A qualified HVAC assessment should address those issues separately.
Common questions
Repair vs replace, without a rule of thumb.
Is it cheaper to repair or replace a furnace?
It depends on the actual repair quote, replacement quote, heating cost, efficiency difference, comparison period and likely future repairs. Use those inputs rather than a fixed percentage rule.
Is furnace age enough to decide?
No. Age affects expected reliability and future-repair risk, but it does not tell you the condition of the heat exchanger, controls, blower, venting, installation or overall system.
Will efficiency savings pay for replacement?
Not necessarily. The calculator estimates the fuel-cost difference from your AFUE assumptions and shows a simple payback from fuel savings alone.
When should cost stop being the deciding factor?
If a carbon-monoxide alarm activates, a qualified technician identifies a safety issue, or the equipment cannot be operated safely, follow the relevant safety or professional guidance.