When to Repair or Replace a Furnace Heat Exchanger. There are several ways to determine if you need to replace or repair your heat exchanger (which costs) between $150 and $300 on average.

How Much Does It Cost to Replace a Heat Exchanger in a Furnace? It’s a major undertaking that can cost as much as $3,000 and take up to eight hours, depending on the furnace model.

Furnaces usually last between 15 and 20 years. If your heat exchanger fails when the furnace is 10 years old or more, it might be best to purchase a new furnace rather than replace the heat exchanger.

He wanted to replace his older furnace with one that was more efficient, and to that end he built a heat exchanger into the design. This way the exhaust will preheat the intake air.