Most furnaces last between 15 and 20 years. However, exact longevity depends heavily on your system type, usage, and maintenance habits.
The $5,000 rule is a guideline to help homeowners decide whether to repair or replace their HVAC system. You multiply the age of your unit by the cost of the needed repair. If that number exceeds $5,000, replacing your HVAC system is often more cost-effective.
5 Warning Signs It's Time for Furnace Replacement
You may be able to improve efficiency by replacing a part, but if your furnace is 15+ years old, a new furnace will be more efficient and more cost-effective. You'll save money on repair bills and future energy bills.
Average Cost to Replace a Furnace
However, the cost of furnaces can range widely depending on their size, type, and efficiency, and homeowners can generally expect a new furnace to cost anywhere between $3,800 and $10,000. If efficiency is important to you, high-efficiency models can reach up to $12,000.
The best time to buy a furnace is during the off-season, specifically late spring (April-May) or early autumn (September-October), when HVAC companies are less busy and offer lower prices, rebates, or promotions. Purchasing in these shoulder seasons ensures faster installation times and better negotiating power compared to winter peak season.
If you make qualified energy-efficient improvements to your home after Jan. 1, 2023, you may qualify for a tax credit up to $3,200. You can claim the credit for improvements made through December 31, 2025. For improvements installed in 2022 or earlier: Use previous versions of Form 5695.
The heat exchanger is often considered the most costly part of a furnace to repair or replace. It is a critical component that transfers heat from the combustion process to the air that circulates throughout your home. Over time, heat exchangers can crack due to the constant heating and cooling cycles they undergo.
Yes HVAC prices have steadily increased over the past few years, and 2026 is no exception. These increases are affecting everything from entry-level systems to high-efficiency units, making it more expensive than ever to install or replace HVAC systems.
Short cycling
This is one of the most common furnace problems, and it can stress important furnace components such as the blower motor, limit switch, or flame sensor. There are several potential causes of short cycling, including some that are related to your furnace's built-in safety systems.
If your furnace is not turning on, the most common causes are incorrect thermostat settings, a tripped circuit breaker, or a clogged air filter. These issues either interrupt power supply or trigger built-in safety switches that shut the system down to prevent overheating.
Scraping Sounds
Ask an expert, “What does a failing furnace sound like?” and they'll tell you to pay attention to any scraping or grinding noises. This distinct sound might indicate loose parts or issues with your blower motor.
You know it is time to replace your furnace when it is over 15 to 20 years old, requires increasingly expensive repairs, or struggles to maintain consistent heating. Waiting for a total, freezing-weather breakdown leaves you with higher costs and limited options, so being proactive is crucial.
How Do I Claim a New Furnace on My Taxes? As a homeowner, you can claim a credit on your energy-efficient furnace by filling out Form 1040 (or 1040NR for non-resident aliens). To determine your credit amount, complete the Residential Energy Credits Form 5695.
Ideally, you would have your furnace serviced at least once a year. To elaborate on that point, you should have your furnace serviced at least once a year to catch any problems early on and to keep your furnace in top condition. Professional maintenance and cleaning provide many benefits, which we'll cover next.
The "two-foot rule" in HVAC is a duct design and installation guideline that requires a minimum of 24 inches of straight, uninterrupted space between branch take-offs (where air taps off the main trunk). It is also applied to spacing branches away from end caps, transitions, and the main plenum.
Federal tax credits for residential furnaces and HVAC systems expired at the end of 2025. If your furnace was installed and placed in service in 2026, it no longer qualifies for the Section 25C Energy Efficient Home Improvement Credit.
A new furnace can cost anywhere from $3,500 to $7,500 in 2026, depending on fuel type, efficiency, and installation requirements. If you're replacing both the furnace and air conditioner, most homeowners spend $5,000 to $15,000 for a complete system upgrade.
While rare, a furnace can last up to 30 years with excellent maintenance, but most systems begin to lose efficiency and reliability after 15 to 20 years.
What fails first on a furnace? The most common early failures are the furnace ignitor or flame sensor, as they experience regular wear and tear and are critical to starting the heating cycle.
Homeowners insurance may cover the cost to repair or replace your furnace or boiler if it's damaged or destroyed by a covered peril. Covered perils as defined by your policy typically include events such as: Lightning. Fire.
For the 2025–2028 tax years, individuals age 65 or older by the end of the tax year can claim an additional $6,000 deduction ($12,000 for married couples) under the "One, Big, Beautiful Bill". This deduction requires a Modified Adjusted Gross Income (MAGI) below $75,000 for individuals ($150,000 joint) and is available regardless of whether you itemize or take the standard deduction.
The most chronically overlooked tax deductions are state sales tax (valuable if you made major purchases or live in a state without income tax) and out-of-pocket charitable expenses. Because taxpayers focus on major items like mortgage interest, these small-but-mighty write-offs frequently slip through the cracks.
In 2026, you can receive factory-direct rebates of up to $𝟏,𝟖𝟎𝟎 when purchasing a qualifying Lennox Ultimate Comfort System Spring 2026: Lennox AC Rebates Up to $1,800 | Symbiont Service. To maximize your savings, you can combine these with available utility rebates and federal tax incentives Utility Company & Manufacturer Rebates | Lennox & Mitsubishi ....