Common Types of Chemically-Induced Heat Exchanger Failure


In most cases, you will not think much of your furnace until it stops working optimally. There are several parts in your furnace, but the key one is arguably its heat exchanger. This is simply the part that heats air. It comprises coils and tubes that are looped to maximize the surface area for the heating of your air.

The heat exchanger might be the reason you need heating repair for your Riverton property. Unfortunately, most property owners do not think of the heat exchanger as the cause of their furnace’s breakdown since it has no moving parts. There are different types of chemicals, which circulate through the heat exchanger, and these might interact with the metal to cause various forms of chemically induced corrosion.

General Corrosion

This form of corrosion comprises a somewhat uniform attack over your exchanger’s tube or shell. In extreme cases, general corrosion will cause the total breakdown of your exchanger’s material. Fairly stable chemicals with low pH mixed with oxygen and carbon dioxide are the common causative agents of this type of corrosion. A furnace expert can help you choose the best heat exchanger material for the chemicals that circulate in your furnace to reduce general corrosion.

Pitting Corrosion

This results from a difference in the oxygen concentration inside and outside your heat exchanger, which causes an electrochemical potential. Pitting corrosion usually occurs from a periodic furnace shutdown, which forms an environment for the accumulation of chemicals in one part of the heat exchanger. This increased risk of chemical damage will be further compounded by scale deposits, dirt, and scratches, which further break down the protective layer of your heat exchanger.

Stress Corrosion

Furnace Filter

This attacks the boundaries of your heat exchanger’s stressed areas. These areas include the U bends and the expanding areas of your tube’s sheets. Failures generated by stress corrosion are generally evidenced by fine cracks along the lines of stress and the heat exchanger’s boundaries. In stainless steel heat exchangers, the causative compound of stress corrosion is chloride ions from the water that circulates in the furnace.

Crevice Corrosion

This form of corrosion is found in the secluded and hidden areas of your heat exchanger, such as the inner tubes and baffles or under loose dirt. Before the eventual failure of your heat exchanger, the affected area will appear slightly eroded. Unlike in mechanical failure, heat exchangers destroyed by crevice corrosion have sharp cuts rather than pits.

To alleviate this damage, you should keep the fluids in your furnace continually moving. This prevents stagnation of liquids and the buildup of solids in one area, which both contribute to corrosion.

The best way to prevent the above forms of corrosion is by scheduling a regular furnace tune-up. In this service, any corrosion is noticed in its initial stages, and the formation of pits and cracks is averted. The poor installation of your furnace will also contribute to the occurrence of chemically induced damage. Though a DIY installation might save you a few dollars initially, it will cost you a new heat exchanger again within a few months, which will not come cheap.

Read more at Children First America.

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