The decision in one line
Repair when the system is relatively young, the fix is modest, and it's safe. Replace when the furnace is near the end of its life, the repair is a large share of replacement cost, efficiency is poor, or there's a safety issue. The trick is being honest about which side you're on.
The four tests
- Age. Under ~10 years: lean repair. 15+ years: replacement enters the conversation. 20+: replacement is usually the better long-term spend.
- The 50% / cost test. If a single repair approaches half the cost of a new furnace — or you've had multiple repairs in two years — replacement usually wins.
- Efficiency. An old 70–80% AFUE furnace wastes 20–30 cents of every heating dollar. A modern 95%+ furnace can cut that meaningfully over a long Minnesota heating season.
- Safety. A cracked heat exchanger or a carbon-monoxide concern moves you to replace regardless of age — this is non-negotiable.
When repair is the right call
A younger furnace with a failed igniter, flame sensor, capacitor, or control board is almost always worth repairing — these are common, bounded fixes. Don't replace a 7-year-old furnace over a $300 part.
Failure modes of a bad decision
Two traps: pouring repair money into a 20-year-old furnace one part at a time, and being scared into a replacement for a part that's a simple fix. Get the heat-exchanger and safety status in writing, and get the repair-vs-replace numbers side by side.
Proof / how Midland approaches it
Midland has replaced furnaces for the same Twin Cities families for decades — and talked plenty of homeowners out of a replacement when a repair was the smarter spend. We give you the age, the repair cost, the efficiency delta, and the safety status, and let the numbers make the case.
What to do next
If you're leaning replace, also weigh whether a heat pump or dual-fuel system fits before you buy a like-for-like furnace. If you're leaning repair, a tune-up plan keeps the next surprise smaller.