Furnace Replacement Cost Planning Range (2026)

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Define the furnace and the work before comparing prices

The existing HomeScore model covers an installed 80k–100k BTU gas furnace with professional labor, standard materials, startup and a permit/inspection allowance. Major ductwork, asbestos or mold remediation, structural work and fuel conversion are outside that range. Those boundaries describe the planning model; they do not promise that a contractor's bid includes the same items.

A furnace heats air; it is not the same purchase as a boiler, heat pump or a complete AC-and-furnace package. Start by identifying the system and fuel you have and the proposed replacement. If a proposal includes cooling equipment or a change of fuel, separate that work so an apparently higher total is not mistaken for a higher price for the same job.

Keep equipment and installation prices separate when the contractor supplies that breakdown. Then compare the complete installed proposal, not an equipment-only internet price against a finished job. Ask what happens if hidden work is discovered. A blank line is unknown, not included, and a verbal assurance should be reflected in the written scope before you rely on it.

Normalize every written quote

Use these six headings to compare the same work. This worksheet organizes evidence; it does not diagnose equipment or determine a fair local price.

Compare capacity and efficiency without a savings promise

DOE defines AFUE as useful heat output divided by fuel energy input over a heating season, expressed as a percentage. It is an efficiency measure, not a capacity rating or a prediction of your household bill. Record both input and output capacity and AFUE so you can see which part of a proposal describes size and which describes efficiency.

ENERGY STAR uses different gas-furnace efficiency criteria for northern and southern regions. Its product page also points homeowners toward insulation, air sealing, duct sealing and maintenance. Ask how the proposed equipment fits your location and home. Do not copy a federal purchasing requirement or a label threshold into a claim that every homeowner must buy that model.

DOE's sizing guidance starts with heating and cooling load calculations. Ask what information supports the proposed furnace size and whether changes to windows, insulation or the house affect it. The 80k–100k BTU example on this page is a model boundary, not a recommendation for your address. Replacing an old unit with the same capacity does not itself establish correct sizing.

When comparing a higher-efficiency option, ask for the installed price difference and the assumptions behind any operating-cost estimate: fuel price, heat demand and expected use. Keep rebates or incentives separate until eligibility and current terms are confirmed. This guide makes no payback, tax-credit or bill-savings promise and does not use DOE's federal-facility examples as your home's forecast.

Use age and symptoms to ask better questions

ENERGY STAR lists a furnace or boiler more than 15 years old, frequent repairs and rising bills among reasons to consider professional advice about replacement or system improvements. That is a prompt to assess options. A date alone does not establish remaining life, the cause of a symptom or whether replacement is the best choice for a particular home.

Ask what failed, how the diagnosis was established, what a repair would address and what remains uncertain. Compare a documented repair option with a separately described replacement option when both are appropriate. Avoid treating a fixed age or repair-cost percentage as a universal rule. Keep safety concerns with a qualified professional; this page is not a combustion, gas, electrical or venting repair tutorial.

Before choosing between bids, separate ordinary equipment replacement from corrections to the existing installation. Ask who checks venting, combustion-air provisions, condensate handling, fuel and electrical connections, controls and duct connections. These are scope questions for the qualified installer, not instructions to inspect or modify those components yourself.

Planning method, source limits and records

Reviewed October 18, 2026. The $4,500 low, $6,800 midpoint and $10,500 high preserve HomeScore's existing furnace planning method. They are not newly collected prices. No verified invoice sample, local bid distribution or confidence interval is available for these amounts. A quote outside the model is a reason to examine scope, not proof of overcharging or a bargain.

DOE and ENERGY STAR support the efficiency, sizing and assessment context below; they do not substantiate HomeScore's dollar amounts. DOE's linked purchasing guide is written for federal buyers and includes dated illustrative assumptions. This homeowner page uses its AFUE explanation, not its purchasing mandates, lifetime assumptions or calculated savings as a prediction for your home.

After choosing a proposal, keep the agreed scope and any written changes with the final invoice and equipment records. Confirm who provides startup results, applicable inspection evidence and warranty documents. Record the installation date only when supported by the paperwork. That evidence makes the next maintenance, repair or replacement decision more useful than a generic age estimate.

Furnace replacement questions

Is $6,800 a national average?

No. It is HomeScore’s authored planning midpoint for the stated gas-furnace scope. No verified invoice sample establishes a national average or a local fair price.

Does this include a central AC unit?

No. This model covers an installed gas furnace. AC plus furnace, a heat pump, an oil system or a fuel conversion requires its own scope and written proposal.

Does a higher AFUE guarantee a lower bill?

No. AFUE describes seasonal fuel-use efficiency. Actual bills also depend on heat demand, weather, fuel prices, installation and use. Compare stated assumptions rather than accepting a guaranteed savings figure.

Should I replace a furnace after 15 years?

ENERGY STAR identifies a furnace or boiler more than 15 years old as a reason to consider replacement or system improvements with a professional. Age is a prompt for assessment, not proof of failure or an automatic deadline.

Can I reuse the old furnace size?

Do not assume it is correct. Ask the contractor for the load calculation and proposed capacity, especially after insulation, window or layout changes. The 80k–100k BTU planning example is not a sizing recommendation.

What should I save after installation?

Keep the accepted scope, changes, final invoice, model and serial records, startup results, applicable inspection record and warranty terms. Mark missing evidence as unknown rather than assuming the work was included.

Related planning guides

Furnace cost by state · AC plus furnace scope · Heat-pump replacement · Documented HVAC age · Lifespan reference method · Home-system cost guides

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