Furnace Replacement Cost: Gas, Electric, and Oil Prices Explained

Furnace Replacement Cost by Fuel Type

Gas furnaces dominate American homes and offer the best balance of installed cost and operating cost where natural gas is available. A standard 80% AFUE unit (meaning 80 cents of every fuel dollar becomes heat) installed runs $3,000 to $5,000. Stepping up to a 96 to 98% AFUE condensing furnace runs $4,500 to $8,000 installed but can cut heating fuel use by 15 to 20 percent — meaningful in cold climates with long heating seasons.

Electric furnaces are the cheapest to install at $2,000 to $4,500 because they need no gas line, flue, or combustion air. The tradeoff is operating cost: in most of the country, electric resistance heat costs two to three times more per BTU than gas. They make the most sense in mild climates or homes without gas service where a heat pump isn't practical.

Oil furnaces, concentrated in the Northeast, run $4,000 to $9,000 installed. Fuel oil prices are volatile, and annual maintenance is heavier than gas, but a modern oil furnace is far cleaner and more efficient than the unit it typically replaces.

Propane furnaces mirror gas furnace pricing for the equipment ($3,000 to $6,500 installed) but require a tank and carry higher fuel costs than natural gas in most markets.

What Else Shows Up on the Invoice

The furnace itself is often only 50 to 60 percent of the installed price. Labor, sheet metal transitions, venting, gas line work, electrical, condensate drainage, the thermostat, permits, and haul-away make up the rest. This is why 'the same furnace' can be quoted $1,500 apart by two contractors — the scope around the box differs.

High-efficiency condensing furnaces vent through PVC pipe rather than a metal flue and produce acidic condensate that must be drained. In a home with an old chimney flue, that means running new vent pipe — often a few hundred dollars of additional labor, and more if the routing is difficult.

Ductwork is the silent budget item. If your ducts are undersized, leaky, or poorly insulated, a new high-efficiency furnace connected to bad ducts performs like a mediocre one. Sealing and modest modifications typically run $500 to $2,000; significant replacement runs $3,000 to $7,000 or more.

If your air conditioner is the same age as the furnace, ask about replacing both together. The indoor coil sits on top of the furnace, so doing both at once saves a full labor visit and ensures the components are matched — see our HVAC repair or replace guide for the full decision framework.

Sizing: Why Bigger Is Worse

Furnaces are sized in BTUs, and the correct size comes from a Manual J load calculation — a room-by-room assessment of your home's insulation, windows, orientation, and air leakage. Rule-of-thumb sizing by square footage alone is how homes end up with furnaces 50 percent too large.

An oversized furnace heats the house so fast that it shuts off before completing a proper cycle, then restarts minutes later. This short-cycling means uneven temperatures, more noise, higher fuel use, and a heat exchanger that wears out years early. If a contractor quotes a size without measuring anything, that is a red flag — ask what load calculation they used.

Repair or Replace: The Decision Framework

Furnaces typically last 15 to 20 years with maintenance. Two rules of thumb cover most decisions. First, the 50 percent rule: if a repair costs more than half the price of a new unit and the furnace is past the middle of its expected life, replacement usually wins. Second, the frequency test: if you've paid for two or more repairs in the last two heating seasons, the failures tend to accelerate.

One repair is never optional: a cracked heat exchanger. It can leak carbon monoxide into the airstream, and on an older furnace the repair cost approaches replacement cost anyway. If a technician condemns your heat exchanger, get a second opinion promptly — but treat it as a safety issue, not a sales tactic, until proven otherwise.

When you're ready for quotes, get matched with local HVAC contractors through Home Services Pro USA — free for homeowners, with no obligation to hire.