Types of Mechanical Failures in Furnace Heat Exchangers

a man fixing the furnace

Indoor heating is an integral part of all properties. There are various indoor heating solutions, but most property owners opt for furnaces. The core of your furnace’s function is its heat exchanger. The heat exchanger comprises no moving parts, and most people assume they can work with minimal or no maintenance.

One of the frequent reasons for heating repair in Raleigh properties, however, is heat exchanger cracks. There are various causes of cracks in heat exchangers, but mechanical failure is the most common one. Here are the different types of mechanical failure that cause cracks.

Metal Erosion​

Fluids run through your heat exchanger at a high velocity throughout. This fluid velocity on both sides of your heat exchanger causes erosion of the metal inside your tubes. U-type heat exchangers are the most vulnerable to metal erosion, especially at their U-bend. Sometimes, metal erosion might occur on the surface of your tubes due to impingement of high-velocity wet gases like steam.

Thermal Fatigue​

The repeated thermal cycling of your furnace’s operation results in accumulated stress on your heat exchanger. This process typically leads to thermal fatigue, which over time exceeds the tensile strength of the heat exchanger’s material and cracks it. Cracks from thermal fatigue usually run radially and result in complete breakdown of your heat exchanger.

Thermal Expansion​

This type of mechanical failure is widespread in steam-heated exchangers. Any exchanger without an adequate provision for thermal expansion is, however, prone to failure from thermal expansion. Continuous thermal expansion results in excessive pressures, which exceed the strength of your exchanger’s material and causes cracks.

A cracked heat exchanger might not seem like a significant issue for some property owners. Cracks from the above forms of mechanical failure, however, result in insufficient combustion of gases and leakage of carbon monoxide in your indoors. It also causes over 50% energy inefficiency with your furnace’s operation.