HVAC Repair & Replacement Cost in Knoxville, TN

Knoxville prices for HVAC and duct work

† Central AC replacement: High end reflects two-stage and variable-speed equipment, larger homes, and duct modifications; a standard-efficiency change-out on sound ductwork lands in the lower half.

† Furnace replacement: Electric furnaces sit at the low end; gas furnaces run $3,800 to $10,000 in most guides, and high-efficiency condensing units push past the high end.

† Heat pump installation (air-source): Sources disagree widely (>3x): contractor-network averages (Angi, Bob Vila, Today's Homeowner) cluster near $6,000 for a like-for-like change-out, while HomeGuide, This Old House, and Carrier quote $10,000 to $25,000 for higher-efficiency and cold-climate systems. Range widened to cover both.

† Ductwork replacement: Whole-home replacement in a 1,500 to 2,500 sq ft house; replacing a few runs costs a fraction, and retrofitting ducts into a home that never had them runs above the high end.

In an older Knoxville house, start with the ducts

Uneven rooms, a high power bill, and a system that runs constantly are often blamed on the furnace or heat pump when the ducts are the cause. Ducts in older houses tend to leak at joints, lose heat through thin or missing insulation in attics and crawlspaces, and lack enough return air. Sealing and insulating the worst runs costs a fraction of a full replacement; whole-house ductwork replacement runs $1,000–$5,500 for a typical home, and adding ducts to a house that never had them costs more than the top of that row.

That changes how to budget a Knoxville replacement. New equipment connected to leaky, undersized ducts will not deliver its rated efficiency or comfort. Before you sign for a new system, ask the contractor to test or at least inspect the ducts, and to price any duct work as its own line so you can see what you are paying for.

Very old systems raise a second issue. Air conditioners and heat pumps installed before about 2010 often use R-22 refrigerant, which is no longer produced. A leak on an R-22 system is expensive to recharge and usually a sign the system is due for replacement.

Heating demand 9th of 33, with an 88°F July

The Knoxville McGhee Tyson Airport station, 17 km from the city center, averages 3,528 heating degree days and 1,574 cooling degree days in NOAA's 1991-2020 normals. Cooling claims 31% of Knoxville's combined total. The January average low is 30°F, about 67 nights a year fall to freezing, and the July average high is 88°F, with roughly 37 days at 90°F or above and 0 at 100°F. The station sits at the airport outside the city, so a house in a hollow or on a ridge may run a few degrees off these figures.

Heat pump, gas furnace, or both for Knoxville winters

Heat pumps work well in Knoxville's climate, but the heating side is heavy enough that the backup heat deserves attention. When it gets cold, a heat pump leans on electric resistance strips, which cost much more to run. A cold-climate model, or a dual-fuel setup with a gas furnace for the coldest nights, keeps winter bills in check. An air-source heat pump runs $4,100–$14,700 here; cold-climate models sit toward the top.

If you have gas, a furnace with a separate AC is still a sound choice. Budget $2,700–$7,400 for a new furnace and $3,900–$11,800 for a new central AC. In older houses, a furnace past 20 years deserves a heat exchanger inspection, since a crack can leak carbon monoxide and usually ends the furnace's life.

Whatever you choose, new split systems use R-454B or R-32 refrigerant, and Tennessee is in the Department of Energy's Southeast region, where new air conditioners must reach 14.3 SEER2.

Knox County wind, falling limbs, and the condenser

Knox County reported 92 days of damaging thunderstorm wind from 2016–2025, ranking 5th of 33, with gusts up to 72 mph. Hail was less frequent: 18 days with stones an inch or larger, and the largest was 1.75 inches. For a condenser here, a falling limb is a likelier storm hazard than hail.

Homeowners insurance usually covers that kind of sudden damage, a fallen tree, lightning, fire, or hail, after the deductible. It does not cover a decades-old system that simply quits. Wear, age, and mechanical breakdown are excluded, which describes most furnace and AC failures in older housing. A manufacturer warranty may cover parts on newer equipment but rarely labor, and a home warranty plan is a service contract designed for breakdowns.

What older-house HVAC work costs at Knoxville labor rates

Because federal statisticians withhold Knoxville's metro construction wage, the 0.98 labor factor on this page comes from the Tennessee statewide figure. Nashville comes out at 1.02 and Charlotte at 0.95. For an older house, a tune-up ($50–$350) that includes a duct and heat exchanger check is a low-cost way to decide whether you are facing a repair or a replacement.

Knoxville HVAC questions, from ducts to heat pumps

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