Fin tube heat exchangers are subject to fouling, which takes place as long as there is an airflow or waterflow in the unit. Defined as thermal resistance due to the accumulation of contaminants on heat transfer surfaces, fouling negatively affects heat exchanger efficiency, longevity, and increases system operating costs.

Systems designed to cool air, whether for HVAC, industrial facilities, or manufacturing operations all have to address it. Failure to address it can lead to botched processes, reduced production, ruined equipment or uncomfortable building occupants. It can be expressed in percentage, lb./lb., wet bulb temperature, or other metrics. The silent “it” is humidity. Put simply, humidity is a measure of the amount of water vapor in the air, and while overlooking this simple measure can be costly, it can also be readily addressed during system design.

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Oftentimes, using stainless steel components seems like a simple solution to corrosion on coils. You may see fins or tubes or other parts of the system show signs of corrosion, and it seems that the best option is to change the coil to stainless steel, solving the corrosion problem permanently. While this seems like a simple solution to a significant problem in the HVAC, industrial, and commercial systems where coils are found, the answer to the question “should I make an all-stainless coil?” is far more complex.

An 800MW 2x1 combined-cycle power plant in Alberta, Canada was experiencing consistent frost issues on anti-icing coils in their gas turbine inlet filter houses. The purpose behind these coils is to bring the temperature of the air up to just above the dew point, to prevent the condensation of water (which can cause serious damage through icing if introduced into the turbine.)