Gas fired furnace heat exchangers most often fail from?

Gas fired furnace heat exchangers most commonly fail due to rust and metal fatigue. Over time, the heat exchanger experiences extreme temperature fluctuations during operation. When gas combustion occurs, it produces moisture and carbon byproducts that can lead to corrosion. The constant cycling of hot and cold causes the metal to expand and contract, which can lead to metal fatigue. This is particularly true in environments where humidity is present, as the moisture accelerates rusting.

Regular maintenance and proper installation can help mitigate these issues, but as the system ages, it becomes increasingly susceptible to such failures. Understanding these key factors is essential for both homeowners and inspectors in identifying potential issues before they lead to significant problems.