A high-efficiency furnace typically lasts 15 to 20 years. While they are built to last, their lifespan heavily depends on proper installation, regular maintenance, and the quality of the unit itself.
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.
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.
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.
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.
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.
Since the cost to install an HVAC system can vary by system type and other factors, it's important to understand your financing options.
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 the furnace is 15 years or older, then it's likely that a full replacement is needed. In addition to the age of the unit, here are a few things that you should look for to determine whether it's time to replace your furnace: Constant emergency repairs. Increased energy costs.
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.
Best Furnace Brands of 2026 for Efficiency, Reliability, and...
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.
Furnace Tax Credit Amounts and Limits for 2025
Federal HVAC tax credits allow homeowners to claim a maximum annual credit of up to $3,200 for qualifying HVAC upgrades made between 2023 and 2025.
This tax credit is effective for products purchased and installed between January 1, 2023, and December 31, 2025. Claim the credits using the IRS Form 5695.
The best time to buy a new HVAC system is during the off-peak seasons, particularly in winter months (December through February) and early fall (September through October).
High-efficiency furnaces may require more frequent check-ups by qualified technicians to maintain their optimal performance levels. Additionally, when repairs are needed, they can be more costly and complex due to the specialized components and technology involved.
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.
If you smell something like burning plastic or a strong and unpleasant smell like formaldehyde, your furnace has serious issues. Turn off the power and call for immediate furnace repair. If you smell rotten eggs, that is the smell the gas company adds to natural gas to warn you of a gas leak.
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.
In short, the 20-degree rule of air conditioning states that you should always keep your AC unit at no more than 20 degrees lower than the outside temperature. It means that, if the outdoor conditions are at 95 degrees, you should set your thermostat at no less than 75 degrees.
The following are the most costly parts to fix or replace:
Furnace replacement may be covered by homeowners insurance if it was damaged by a covered peril. For example, fire, storm damage, or water from a burst pipe could qualify as sudden and accidental events that trigger coverage up to your policy's limits.
Eligibility for HVAC loans varies by lender and loan type, but common requirements include: Credit score: Most lenders look for a score of 600 or higher. The better your score, the lower your interest rate. Income verification: Be prepared to show recent pay stubs or tax returns.