Cleaning and maintaining of boilers, reverse osmosis (RO) systems, chillers, and ion exchange resin (IER) involves a combination of regular inspections, cleaning of components, and preventative measures to ensure optimal performance and longevity. Boilers require periodic cleaning of tubes, and combustion chambers to remove soot, scale, and sediment, while RO systems need regular filter replacement and membrane cleaning. Chillers benefit from cleaning condenser coils and water circuits, and IER systems require regular inspections and maintenance to get optimum performance.