New Furnace Replacement Cost and Installation Cost 2021

The average cost to replace a gas furnace is $3,550 for a 100,000 BTU furnace.

The total price range is $1,750 to more than $6,000 based on cost factors like furnace size and features.

Furnace SizeAve Total CostAve Home Size
40,000 BTU$2600600-1000 sf
60,000 BTU$30851000-1400 sf
80,000 BTU$33501400-1800 sf
100,000 BTU$37251800-2300 sf
120,000 BTU$43502300-2800 sf
140,000 BTU$46852500-3200 sf

Note: House size is used for basic reference only. It is just one of many factors that determine what size furnace you should install.

This table shows average installed furnace costs for common sizes. The cheapest, smallest furnaces cost less. The largest, most expensive furnaces cost more.  

Note: House size is used for basic reference only. The size of the house is just one of many factors that determine what size furnace you should install.

Overview of Furnace Replacement Cost

This guide focuses on cost. Important factors like furnace size, features, performance and efficiency are considered.

We itemize all possible costs, so you can closely estimate what your furnace cost will be.

Because we account for all costs, our price estimates are accurate.

If you want more details about cost factors, they are comprehensively discussed in our Gas Furnace Buying Guide that is updated each year for accuracy.

It also has more pricing details like furnace prices by brand.

Information on choosing the right size and efficiency for your home and climate is included.

Gas Furnace Replacement Cost Breakdown

Here’s an itemized look at costs:

  • Furnace only – 80% AFUE: $700 – $2,400
  • Furnace only – 90% or higher AFUE: $995 – $3,650
  • Installation labor cost: $1,050 – $1,975
  • Potential extra costs (see next section): $400 – $1,000+
  • Total potential cost range: $2,150 – $6,625 plus zoning and ductwork, if required.

Potential Extra Costs

Here are common costs incurred when installing a furnace.

  • New plenum: $150-$275. The plenum is fabricated from sheet metal and connects the furnace to the ductwork where heated air from the furnace flows into the ducts.
  • New cold air return: $200-$325. This connection is between the cold-air return ducts and the furnace.

In a few cases, an old plenum and/or return can be used when replacing a gas furnace. The new furnace must be the same size with the same size openings, and that is rare.

  • Electrical circuit and wiring: $325-$615. When a furnace is being installed in new construction, a dedicated circuit might need to be added to the electrical box.
  • Thermostat: $40 – $500+ installed. Cheap thermostats start at less than $20 for the unit Nest, ecobee, Lux, Lyric and similar smart thermostats range up to $300 or more. LCD touchscreen WiFi thermostats can cost $500+.

If the new furnace is much like the old one, a new thermostat might not be necessary.

Your thermostat options are discussed in our Thermostat Buying Guide. It includes links to our reviews of the top thermostat brands like those mentioned above.

  • Ductwork: $3,000 – $4,500. Of course, you’ll need ductwork for new construction. Existing ductwork can usually be used if it is in good condition and rated for the size furnace being installed. Complete details are found in our Ductwork Cost Guide
  • Zoning: $2,000 – $3,300. Zoning allows you to separately control the temperature in two or more zones. Each zone has its own thermostat. Dampers in the ducts open or close accordingly. All the details are in our Zoning Guide

Gas Furnace Replacement Cost Factors

This section will assist you in narrowing down your cost estimate. There are more details in our Furnace Buying Guide. Click the Furnace tab at the top of the page to access it.

1). Gas furnace efficiency: Your options are 80% AFUE or 90% to more than 98%.

An 80% furnace is OK for warm climates and part-time locations.

When the furnace gets heavy use, as in cold regions, a 90% furnace is required. The colder your climate, the more efficient the furnace should be.

2). Gas furnace performance: Your options are single-stage (100% capacity), two-stage (70% and 100%) and variable capacity (from 40% to 100% in small increments) furnaces.

Variable capacity models are only available in 95% or higher efficiency.

The more stages of operation, the more temperature in your home will be balanced and comfortable.

3). Gas furnace size: As noted, they range from about 40,000 to 140,000+ BTUs. In any model, cost goes up $150 – $500 per 20,000 BTUs.

How large should your furnace be? There are a dozen or more factors considered by HVAC pros: House size, climate, home’s insulation, windows and doors, number of levels, etc.

All factors are considered in a load test should as a Manual J that can be conducted by a furnace pro. They are discussed in great detail here.

4). Gas furnace quality: We sort brands into Budget (12-15 years of durability), Standard (15-20 yrs) and Premium (20+ yrs). Cost goes up with quality.

See the Furnace Guide to see what brands are in each category.

There are also links to our Reviews for all top brands – Trane, Goodman, Carrier, Heil, Lennox and many more.

Installation cost factors: Installation costs account for about half the total cost of a new furnace. These factors affect the labor part of the estimate.

  • Access: Installing a furnace in a walk-out basement or first-floor utility closet is much easier than doing the work in an attic or crawlspace. Estimators give a lot of consideration to access when determining cost.
  • Installer certification: Most large brands offer factory training and certification. If the installer has been through the program and is labeled a Certified Installer, expect higher estimates. You might get better installation too.
  • Size of the company: Companies with just a few employees tend to provide more competitive estimates than companies with 6+ employees. The smaller companies have lower overhead costs and usually don’t spend as much on advertising.
  • Cost of living: Life is more expensive in large metro areas, especially along the Coasts. Cost of living is lower in small towns and rural areas of the country. Cost of living can affect furnace prices by 40% from cheapest areas to most expensive.
  • Time of year: If your furnace needs replacing in January, cost will certainly be higher than in a month when HVAC technicians are less busy. We’re big fans of pre-emptive furnace replacement, so you can choose when to have the work done. See details below.

How Size, Performance and Efficiency Affect Cost

This table gives a more detailed view of how cost is affected by efficiency and heating performance.

Furnace Size80%
40,000 BTU$1,750 - $2,400$1,900 - $2,650$2,300 - $2,875$2,515 - $3,100$2,735 - $3,650
60,000 BTU$1,980 - $2,785$2,185 - $2,900$2,470 - $3,050$2,725 - $3,600$3,115 - $4,000
80,000 BTU$2,230 - $3,065$2,475 - $3,215$2,950 - $3,575$3,200 - $4,145$3,750 - $4,515
100,000 BTU$2,445 - $3,200$2,950 - $3,675$3,375 - $3900$3,595 - $4,665$4,285 - $5,165
120,000 BTU$2,700 - $3,485$3,395 - $3,965$3,595 - $4,285$3,950 - $5,100$4,495 - $5,570
140,000 BTU$3,100 - $3,750$3,675 - $4,200$3,800 - $4,450$4,325 - $5,450$4,750 - $6,000+

Furnace Buying Tips

What are your goals when shopping for a new furnace?

Most homeowners want the right furnace, installer and price:

  • The right equipment: A furnace with the right size, efficiency and performance.
  • The right installer: In our culture, brands are heavily pushed.

“Buy the right brand, and your furnace will run longer than the other brands.”

That’s not reality for two reasons.

First, most of the top brands use a mix of proprietary and universal parts. In many cases, brands are virtually identical products.

Secondly, this approach doesn’t consider installation quality. Like car mechanics, some installers are experts and some aren’t quite sure what they’re doing.

Correct installation (of any brand) will ensure your furnace runs as efficiently and as durably as you expect.

  • The right price: Get competitive estimates. This is done by asking 3 or more gas furnace companies for estimates and letting them know they are competing for your business.

Quick, Convenient and Competitive Estimates

Compiling a list of furnace companies by asking family and friends for suggestions is a very thorough approach.

Plan to take two or more weeks to gather names, research the companies, make calls and wait for the companies to get back to you. 

If you aren’t in a hurry, this is a fine approach.

When time matters, you can reduce the time to just a few days.

  1. Choose the Free Local Quotes tab or Call the toll-free number
  2. Share brief details about your furnace replacement or repair (5 minutes or less)
  3. Get written estimates from top furnace experts in your area (1-3 days)
  4. Compare estimates
  5. Research each company’s online reviews and ratings
  6. Select a furnace repair or replacement company with the right combination of good ratings, experience and competitive cost
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