Wet Stacking: Causes And Solutions

What is wet stacking?

The term wet stacking refers to a situation where a diesel generator operates at a low proportion of its capacity for an extended period of time, which leads to the accumulation of unused fuel, carbon particles, and moisture in the exhaust system of a generator. A diesel engine needs to have the appropriate air-to-fuel ratio to sustain its designed operating temperature for a complete burn of fuel. When we operate a generator at low loads, it does not reach its designed operating temperature, resulting in wetness in the exhaust system.

What causes wet stacking?

What does happen to a generator when it experiences wet stacking? Excessive deposits will produce backup pressure, reduce turbo efficiency, and, consequently, affect the engine performance. In order to maintain the performance and efficiency of a power generator, it is critical to take preventive measures. If a generator keeps running at low load, deposits will erode key engine surfaces which could lead to permanent damage. In addition, when a diesel power generator operates below its capacity, the pistons do not expand sufficiently to seal the space between cylinder walls and the pistons. Apart from the loss of engine performance, wet stacking will:

  • Shorten engine life by many years
  • Produce smoke emissions
  • Lower maximum power
  • Lead to expensive repair and maintenance

A power generator subject to wet stacking will produce inefficient results, lower than its designed capacity.


It is ideal if the manufacturer of a diesel generator undertakes the maintenance of the system, but most of the companies outsource maintenance of their standby power systems and sign a planned maintenance contract. There are companies which provide load bank testing and commissioning services.

How do you maintain your diesel power systems and avoid issues such as wet stacking?

The function of a load bank is to run the generator at a load that maintains the designed operating temperature and prevents objects from accumulating in the exhaust system. You can find a wide range of portable and permanent load banks depending on your needs and requirements. No matter what industry you are in, it is of paramount importance for you to maintain your industrial power generators.

About Us

At Power Systems Plus, we provide rental load bank solutions to fulfill your generator maintenance and commissioning needs in Edmonton. The objective of our rental load bank service is to ensure that your backup power systems support loads by maintaining voltages and frequencies compatible with the design criteria. Reach us for a free consultation!