How Much Does a New Furnace Cost in St. Louis? [2025 Data]

Thanks to brisk and chilly winters, a reliable furnace isn't just a luxury in St. Louis, Missouri—it's a necessity. The cost of a new furnace in St. Louis is $4,285, with most homeowners spending between $2,605 and $6,142. The cost depends on the type of furnace, your home size, the efficiency rating, and more. Based on several cost factors, here’s what you might pay for a new furnace in St. Louis, Missouri.

Furnace Cost Factors

If you’re ready to install a new furnace in St. Louis, it’s important to understand the factors that influence the price, including the following.

Furnace Size

The heating capacity of a furnace is measured in British Thermal Units (BTUs). This represents the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit. Larger homes need furnaces with higher BTUs to adequately heat the space, which equates to a higher cost. 

In St. Louis, Missouri, homes often require 40 to 45 BTUs per square foot. Because the average home in St. Louis falls between 1,400 and 1,600 square feet, you’ll likely need between 56,000 and 72,000 BTUs. Keep in mind that this depends on insulation levels, energy efficiency, and other factors. 

Here’s how much you might pay for a new furnace based on home size (in square feet) and furnace size (in BTUs):

Type of Furnace 

The type of furnace also influences the price. In St. Louis, natural gas furnaces are the most common due to availability and effectiveness, as well as lower operating costs. Natural gas units require regular HVAC maintenance for optimal efficiency. 

Some homeowners choose electric furnaces instead. These are often less expensive up front but cost more to run. Oil and propane furnaces are less common in St. Louis. 

Here’s what you might pay for each type of furnace in St. Louis, along with their pros and cons:

Efficiency Rating

When installing a new furnace, the annual fuel utilization efficiency (AFUE) rating describes how efficiently your furnace converts fuel into heat. Higher AFUE ratings correlate with higher efficiency and lower energy bills—but at the same time, you can expect higher up-front costs. 

The table below breaks down furnace costs based on energy efficiency:

Ductwork Replacement

You might need to replace ducts if they’re outdated or incompatible with the new furnace. Alternately, some homeowners must repair leaky or damaged ductwork. An HVAC pro can help you with these problems. In St. Louis, Missouri, the average cost to replace ducts is between $376 and $1,072.

Old Furnace Removal

Installing a new furnace means getting rid of your old one. Most HVAC contractors in St. Louis will remove and dispose of your old unit, which can incur a fee ranging from $60 to $300. The cost is often incorporated into your final bill.

Furnace Pro Costs in St. Louis

You should also prepare for the following expenses when hiring a local furnace installation pro in St. Louis, Missouri.

Labor

The cost of living is 11% to 13% less than the national average in St. Louis. Because of this, homeowners often pay less than the national average to repair or replace their furnace. 

Labor costs for a new furnace often fall between $1,000 and $4,000. The higher price is often reserved for jobs where major modifications are needed to existing ductwork, electrical, or gas lines. Installing a furnace somewhere that’s not easily accessible—such as a tight attic, crawl space, or utility closet—can also raise labor rates. 

Permits

In St. Louis, Missouri, all residential heating/cooling units must be installed by a licensed mechanical contractor, and the work requires a permit. This ensures regulation for energy efficiency and safety, as well as local building codes. 

Your HVAC installation pro will likely secure this permit for you, and they’ll add the cost to your final bill. You can expect to pay between $250 and $400 for a permit in St. Louis. 

Once the work is completed, you must get an inspection to check the furnace installation and ensure it meets code. The HVAC contractor will also facilitate this.

Does a New Furnace Increase Home Value in St. Louis, Missouri?

A new HVAC system can increase home value in St. Louis. Thanks to Missouri's cold winters, a reliable furnace is a highly desirable feature when selling a home. 

Prospective buyers will enjoy the peace of mind that comes with an updated furnace. What’s more, new units have energy-efficient upgrades that can lower monthly utility bills—and that’s also an attractive selling point.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We survey real Angi customers about their project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We pair this data with research from reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

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