Repair or replace

Furnace or Heat Pump Repair or Replace: How to Decide

Repair or replace a furnace or heat pump: age guidelines, cracked heat exchangers, failed compressors, efficiency and what the estimate should cover.

Reviewed October 17, 2026 4 sources

A heating failure in winter feels like an emergency, and sometimes it is. But most no-heat calls end with a small part: an igniter, a flame sensor, a capacitor, a pressure switch. The expensive decisions come when the failure is in the heart of the system, a cracked heat exchanger on a furnace or a failed compressor on a heat pump, or when the equipment is simply old enough that any big repair is a poor bet.

This article covers both furnaces and heat pumps, because the questions are the same even though the parts differ. One thing before cost: a fuel-burning furnace produces carbon monoxide, and a cracked heat exchanger or bad venting can put it in the house. A technician who finds that will shut the furnace down, and they are right to. Have working CO alarms regardless of what you decide.

Typical service life

ENERGY STAR suggests considering replacement when a furnace or boiler is more than fifteen years old, and when a heat pump is more than ten. These are planning thresholds, not expiration dates. A well-maintained gas furnace often runs longer; a heat pump works year-round, heating and cooling, so it accumulates hours faster and its compressor ages like an air conditioner’s.

Maintenance history is the better predictor. A furnace with yearly combustion checks and clean filters is a different machine at fifteen than one that has never been serviced. The manufacturing date is on the data plate inside the furnace cabinet or on the heat pump’s outdoor unit.

Repairs that are usually worth it

These cover the large majority of heating calls and are reasonable on equipment of nearly any age that is otherwise sound.

  • Hot surface igniter or flame sensor on a gas furnace. The furnace clicks and shuts down, or lights and goes out after a few seconds. Cheap and quick.
  • Pressure switch, limit switch or a blocked condensate drain shutting the furnace down on a safety lockout.
  • Blower motor, blower capacitor or an inducer motor. Louder, but still routine.
  • Thermostat, control board or low-voltage wiring faults.
  • On a heat pump: capacitor, contactor, outdoor fan motor, defrost control or a reversing valve solenoid.
  • A dirty filter or blocked return. Not a repair, but often the actual cause of short cycling and overheating.

Repairs that usually are not

A few failures are either unsafe to repair or too expensive to justify on older equipment.

  • A cracked heat exchanger on a furnace. This is a safety failure, because combustion gases can mix with the air in the house. The exchanger is the core of the furnace and replacing it on an out-of-warranty unit is a major job that usually costs a large share of a new furnace. Some manufacturers warranty the exchanger for many years, so check; but even with the part covered, the labor is substantial and the rest of the furnace is the same age.
  • A failed compressor on a heat pump past its warranty. Same calculus as an air conditioner: part, labor, filter-drier and refrigerant add up to a large fraction of a new system.
  • A refrigerant leak in a heat pump coil or a failed reversing valve on an older unit, or any major repair on R-22 equipment.
  • Heavy corrosion of the furnace cabinet or burners, or a leaking secondary heat exchanger on a condensing furnace.

The fifty-percent rule of thumb

The usual rule: if a repair would cost more than about half of a comparable replacement and the equipment is past the midpoint of its typical life, replacing it is the better investment. It is a rule of thumb. For furnaces, the fifteen-year guideline and the heat exchanger question usually settle things before the arithmetic does. For heat pumps, it behaves like the rule for air conditioners: small repairs at any age, big refrigerant-circuit repairs only on young units under warranty.

Make the replacement number honest. A furnace replacement may also involve venting, a condensate drain and gas line work; a heat pump replacement means matched indoor and outdoor equipment. If the air conditioner shares the furnace’s blower and is also old, replacing both at once is often cheaper than two visits a few years apart.

Efficiency and rebates

Older furnaces are often far less efficient than current ones. The U.S. Department of Energy notes that in moderate climates a heat pump can be an efficient alternative to a furnace and air conditioner, and ENERGY STAR certified furnaces and heat pumps beat the minimum sold today. What that saves depends on climate, fuel prices, insulation and installation quality, so ask for an operating cost estimate, not just a rating. Some federal credits that applied through 2025 have since changed, and utility and state rebates vary widely; check the ENERGY STAR rebate finder and your utility, and have the contractor confirm the equipment qualifies before you count on it.

What a technician’s estimate should tell you

Before approving a significant heating repair, make sure these are answered.

  • The failed part and the test that confirmed it. A cracked heat exchanger should be shown to you, by camera or by a combustion test, not just asserted.
  • The age of the equipment from the data plate and the warranty status of the part, including any long heat exchanger or compressor warranty.
  • For a furnace: that combustion, venting and CO levels were checked.
  • Parts, labor and any refrigerant separately, the diagnostic fee and whether it is credited, and the warranty on the repair.
  • If replacement is proposed: a load calculation, the equipment and its efficiency rating, and every added line item including permit and disposal.

What to do while you decide

If a CO alarm sounds or anyone feels headache, nausea or dizziness that improves outdoors, leave the house and call emergency services. If you smell gas, leave and call the gas utility. Otherwise, check the thermostat, filter and breaker, and make sure the furnace switch near the unit is on. Use space heaters safely in occupied rooms and let faucets drip in a hard freeze. Note the model and serial number and any error code flashing on the furnace board so a second opinion can be priced without another visit.

Questions people ask

The technician says my heat exchanger is cracked. Do I have to replace the furnace?

You have to stop using it until it is fixed. Whether to replace the exchanger or the furnace depends on age and warranty; on a furnace past fifteen years, replacement is almost always the better choice. Ask to see the evidence either way.

My 18-year-old furnace needs an igniter. Should I bother?

Yes. An igniter is a small repair. Use the visit to get a combustion check and an honest opinion on how much life is left so you can plan a replacement on your own schedule rather than in a cold snap.

Should I replace my furnace with a heat pump?

In moderate climates a heat pump can heat and cool efficiently; in cold climates a cold-climate model or a dual-fuel setup with a backup furnace may be the right fit. Ask for a load calculation and an operating cost comparison rather than deciding on the equipment price alone.

Sources

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