Furnace Heat Exchanger Replacement: What Affects the Cost?

HVAC Logo IconBy Tom MoorDecember 11, 2023

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Furnace flames

When cold air blankets your region, a properly functioning heating system is required to keep your family safe and comfortable. The most important component of a gas furnace is its heat exchanger, which is responsible for generating heat. Issues with the heat exchanger such as cracks and holes can cause your furnace to stop working properly and cause safety issues.

Given that heat exchangers are the costliest and most crucial components in heating systems, it often makes more financial sense to replace the entire furnace when the heat exchanger is compromised. In the vast majority of cases, a deteriorated heat exchanger means the furnace has likely reached its expected lifespan. However, if your furnace is relatively new and still covered under warranty, replacing just the heat exchanger may be worth considering.

It’s critical to consult with a qualified HVAC technician to thoroughly discuss your options. Keep reading as HVAC.com details what a heat exchanger is, how much furnace heat exchanger replacement costs, and the factors that affect the price. When you receive a quote for a heat exchanger or a new furnace, QuoteScore from HVAC.com can analyze it to determine if it’s a fair deal.

How Does a Heat Exchanger Work?

A heat exchanger, which resembles a hot metal shell located inside the furnace, plays two critical roles – it generates heat and safely releases harmful combustion gases. As the combustion gas, typically natural gas, heats the inside of the heat exchanger, cold air passes over the exterior of the heat exchanger. The air is heated and distributed throughout the home via a series of ducts to provide warmth, while the combustion gases safely exit the home through a flue. Many furnaces with an efficiency rating of 90% or higher contain a secondary heat exchanger for an additional level of efficiency.

If your heat exchanger deteriorates and develops cracks or holes, replace it or the entire furnace immediately. A compromised heat exchanger can result in incomplete combustion and carbon monoxide, which can be deadly if it leaks into your living areas.

The Cost of a New Heat Exchanger

The cost of a new heat exchanger typically ranges from $2,000 to $3,000 on average.

What Affects The Cost of a New Heat Exchanger?

  • Warranty. Check your furnace’s warranty to verify if the heat exchanger is still covered. Although warranties vary based on the manufacturer, some include a 10-year limited parts warranty and a 20-year heat exchanger warranty. If it’s still under warranty, you’ll only need to pay for HVAC labor costs.
  • Brand. The furnace’s make and model can greatly influence the price of a new heat exchanger. Some furnace brands are more affordable, which will lower the cost of buying a replacement heat exchanger.
  • Furnace size. Furnaces with larger capacities, measured by British thermal units (BTUs), have larger heat exchangers that can add to the overall furnace heat exchanger replacement costs.
  • The furnace’s age. If your furnace is more than 15 years old, it’s more difficult to find a replacement heat exchanger that matches your unit. If the heat exchanger fails and the furnace is over 10 years old, consider replacing the entire furnace.
  • Efficiency. Higher-efficiency furnaces often utilize two heat exchangers, a primary and a secondary unit. Replacing a heat exchanger for a more efficient heating system incurs higher costs.
  • Accessibility. Furnaces located in hard-to-reach areas such as tight closets or attics drive up the HVAC labor costs.

The Bottom Line on Replacing a Furnace’s Heat Exchanger

If your heat exchanger is rusted or compromised, contact a qualified HVAC contractor to inspect the unit and make a recommendation. In most cases, replacing the entire furnace is the right call since the heat exchanger is the most expensive component of a furnace.

When you do receive a quote for a new heat exchanger or furnace, QuoteScore from HVAC.com can analyze it to tell you what’s good, what’s not, and recommend clear next steps.


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