Reviewed 2026-09-01
Furnace replacement cost in St. Louis, MO
| Scope | Low | Typical | High |
|---|---|---|---|
| 80,000 Btu gas furnace | $3,550 | $4,550 | $6,100 |
| 100,000 Btu gas furnace | $4,170 | $5,340 | $7,160 |
| Ducted air-source heat pump | $7,110 | $9,110 | $12,210 |
How much does a furnace replacement cost in St. Louis?
A furnace replacement in St. Louis typically costs $4,550 for an 80,000 Btu gas furnace, installed on the ducts that are already there. The range for that same straightforward swap is $3,550 to $6,100. A 100,000 Btu gas furnace is typically $5,340. A ducted air-source heat pump, replacing the furnace and using those same ducts, is typically $9,110, from $7,110 to $12,210. None of those prices includes new ducts, a chimney liner, or a panel upgrade.
What the St. Louis labor rate changes
The national starting point for the 80,000 Btu furnace is $4,600 before local labor. St. Louis labor is 0.98 times a national crew. About 48 percent of that furnace price is the crew, so the city moves the hours more than the cabinet. Versus a crew priced at 1.00, that saves about $50. The heat pump uses a 45 percent labor share because more of its price is the machine. Do not compare a heat-pump quote with the furnace row and call the difference a rip-off. They are different machines.
Which size the example home is even asking about
The example house was built around 1952 and is about 1,550 square feet. brick houses and two-families, basements, humid summers and a real winter St. Louis has about 4,740 heating degree days, against 4,000 in the national reference. A colder city is the usual reason a quote jumps from 80,000 to 100,000 Btu. That jump is not proof you need it. An oversized furnace short-cycles: the air gets hot, the blower stops, and the house never feels even. This page will not run a Manual J. It will tell you to ask why the quote left the smaller furnace.
What pushes a St. Louis quote into the high column
Same cabinet location, existing flue or vent that passes, existing gas line, filter door you can reach: that is the typical price of $4,550. The low price is that job with a clear basement or a garage and no code surprise. The high price, $6,100 for the smaller furnace, is a drain on the coil, a condensate pump, a flue that fails inspection, or a second trip. A liner for an old chimney, a move of the furnace to another room, or a duct replacement can honestly sit above the high number. Ask the quote to name those lines. St. Louis brick houses with basements are workable for trades, and the labor factor sits just under national. Humidity in summer and a real heating season mean equipment actually runs both ways. The high column is a two-family with shared electric and a basement drain that does not work. This page is the Missouri side. East St. Louis and the Metro East are not silently included.
The bill after the St. Louis install
Install price and the yearly bill are different sentences. At $1.50 a therm — the price you typed in the bar, not a St. Louis gas tariff — a year of gas heat for the example home is about $1,320, roughly 882 therms. The same heat from a heat pump at 13.2¢ per kilowatt-hour is about $1,310 a year, about 9,935 kilowatt-hours. Ameren Missouri serves the Missouri side. The planning rate is under the national figure. The Illinois side of the river is a different utility and not this page. A heat pump that costs $4,560 more to install does not pay for itself just because the brochure says so. Divide that gap by the yearly difference only if both numbers are for your house. This page will not invent a rebate.
If you rent in St. Louis
A furnace and a ducted heat pump belong to the owner. The price does not change with the lease. Permission does. Use the range to read a landlord’s number. An “emergency” furnace that is several times $6,100 for a standard swap is a question about scope, not a reason to sign a contract on a building you do not own. Reviewed 2026-09-01. Planning model: IECC climate zone, degree-day normals, a metro labor factor, and a residential rate used only for operating-cost context. Installed costs start from published national ranges and scale the labor share. Rents are planning medians, not listings. Reviewed 2026-09-01.
Before you accept a furnace quote in St. Louis, match it to one row. The 80,000 Btu gas furnace is typically $4,550 at labor 0.98. The heat pump is typically $9,110. If the quote is new ducts, say so out loud and stop using this table. The example home is about 1,550 square feet, built around 1952, in a 4,740 heating-degree-day climate.
Questions this page can answer
- How much does a new furnace cost in St. Louis?
- An 80,000 Btu gas furnace, installed on existing ducts, is typically $4,550, from $3,550 to $6,100. A 100,000 Btu furnace is typically $5,340. New ducts are extra.
- How much is a heat pump in St. Louis?
- A ducted air-source heat pump that replaces the furnace is typically $9,110, from $7,110 to $12,210. A wall-mounted mini-split is a different page.
- Does St. Louis need the bigger furnace?
- The city has about 4,740 heating degree days. That is a reason to ask about size, not a reason to buy 100,000 Btu without a load calculation. An oversized furnace short-cycles.