A 100,000-BTU furnace typically costs $3,500-$8,500 installed, with an average near $5,800 for a standard natural-gas replacement. The final price depends on efficiency, venting, ductwork, local labor, and whether the existing furnace is correctly sized.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Installed furnace | $3,500 | $5,800 | $8,500 | Standard gas replacement |
| Furnace equipment | $1,500 | $2,700 | $4,500 | 100,000-BTU input capacity |
| Installation labor | $900 | $1,600 | $2,800 | More for venting or duct changes |
| High-efficiency installation | $5,000 | $7,500 | $11,000 | Typically 95%-98% AFUE |
Installed Price for a 100,000-BTU Furnace
Most homeowners pay $3,500-$8,500 for a straightforward, complete replacement. This range assumes a forced-air natural-gas furnace, an existing compatible duct system, ordinary access, and no major code or electrical work. A basic 80% AFUE model usually falls toward the lower end; a two-stage or variable-speed unit with 95% or higher AFUE generally costs more.
A 100,000-BTU label usually refers to input capacity, not heat delivered to the home. At 80% AFUE, the furnace supplies about 80,000 BTU per hour; at 96% AFUE, it supplies about 96,000 BTU per hour. Capacity alone does not determine the price or prove that this is the right size. Assumptions: U.S. midrange labor, standard natural-gas equipment, existing furnace location, and routine replacement.
What Equipment, Labor, and Venting Add to the Quote
A written estimate should separate equipment from installation work so the homeowner can compare proposals with similar scope. The ranges below are typical components, not amounts that should simply be added together; some contractors include disposal, permits, or small materials in a bundled installation price.
| Quote component | Typical range | Pricing basis | What changes the charge |
|---|---|---|---|
| Furnace equipment | $1,500-$4,500 | Per unit | AFUE, stages, blower, brand tier |
| Removal and installation labor | $900-$2,800 | About $75-$150 per hour | Access, crew size, site conditions |
| Venting and intake materials | $150-$900 | Per job | Vent type, length, wall or roof exit |
| Permits and inspection | $50-$500 | Per job | City or county requirements |
| Disposal and small materials | $100-$450 | Per job | Old-unit removal and haul distance |
Labor often accounts for roughly $900-$2,800 of a standard replacement. A simple swap may take 6-10 hours; relocating equipment, repairing ducts, or rebuilding a flue can extend the job and raise the labor charge.
How AFUE, stages, and venting change the price
Efficiency and controls can add thousands of dollars compared with a basic furnace. An 80% AFUE unit commonly has a lower equipment price and uses a standard metal flue. A 95%-98% AFUE condensing furnace often requires plastic intake and exhaust piping, a condensate drain, and sometimes a nearby electrical outlet. Vent modifications can add around $300-$1,500, depending on route and access.
Single-stage furnaces are generally the least expensive. Two-stage or variable-speed models can add about $500-$2,000 or more, depending on equipment and controls. A conversion from natural gas to propane may require a compatible model or conversion kit and can add roughly $150-$600, excluding any tank or gas-line work. Confirm that the estimate lists the exact AFUE rating, fuel, and venting scope.
Does a 100,000-BTU furnace fit the house size?
House square footage is not enough to establish the right furnace capacity. Insulation, window area, air leakage, ceiling height, and local winter design temperature all affect the heating load. A contractor should use a room-by-room or whole-house load calculation rather than automatically replacing an older 100,000-BTU unit with the same size.
For example, a tight, well-insulated 2,000-square-foot home may need substantially less capacity than a drafty house of the same size in a colder climate. A furnace that is oversized by 20% or more can cycle frequently, potentially reducing comfort and increasing wear. If load calculations indicate a smaller unit, equipment pricing may fall by several hundred dollars, although labor and permit costs may remain similar. Ask for the calculated heating load and proposed output, not just the old furnace’s nameplate.
How replacement labor hours and access affect the bill
For a like-for-like furnace in an accessible basement or utility room, installation commonly takes one workday with a two-person crew. Tight crawlspaces, attic placement, difficult stairways, or a new exhaust route can add several hours or require extra workers. Labor rates also vary considerably: many U.S. markets fall around $75-$150 per technician hour, while high-cost metro areas may exceed that range.
Changing the furnace location, resizing return-air ducts, replacing a gas shutoff, or upgrading electrical service is usually outside a basic swap. These additions may cost $300-$2,000 or more, depending on the work. Have each contractor identify what is included in the quoted labor and what would trigger a change order.
Why furnace quotes vary across U.S. regions
Installation prices in high-cost coastal metros and areas with strong contractor demand may run about 10%-25% above a comparable small-town or lower-cost-market quote. Rural jobs can also cost more when travel, equipment delivery, or limited contractor availability adds expense. Local permit fees and cold-climate installation requirements contribute to the difference.
These percentages are broad comparisons, not fixed regional price lists. A useful estimate should reflect local labor, the actual equipment model, and site-specific work. Compare at least two or three itemized quotes with the same capacity, AFUE, controls, venting, disposal, and warranty terms. A low quote may omit work that appears as an extra charge later.
Repairing an older furnace versus replacing it
A diagnostic visit commonly costs $75-$200, and many ordinary repairs fall around $150-$800. Replacing a control board, inducer motor, or blower motor can cost more, while a cracked heat exchanger may lead to a replacement recommendation because repair cost and safety concerns can be significant. The furnace’s age, repair history, and condition matter alongside the estimate.
For a furnace nearing 15-20 years old, compare a major repair with the full replacement quote and expected operating costs. A repair under about $500 can be reasonable when the unit is otherwise reliable; repeated repairs or a repair approaching 30%-50% of replacement cost call for closer comparison. Get a written diagnosis before deciding that a repair is uneconomical.
Ways to reduce a 100,000-BTU furnace bill
Keep the job scope focused on verified needs. If the ducts, thermostat, and venting are in good condition, ask whether they can remain rather than accepting automatic upgrades. Choose efficiency and blower features based on local fuel prices, utility rates, and comfort priorities; the highest AFUE model does not always deliver the quickest payback.
Schedule before peak cold-weather demand when practical, and compare quotes using the same equipment specifications. Ask whether removal, permits, startup testing, and warranty registration are included. Avoid choosing a furnace solely by matching the old capacity, and do not pay for unnecessary duct replacement without a documented problem. Clear scope and comparable bids are the most reliable ways to control the total price.