The evaporative cooling part that requires regular replacement is the cooler filter pads/media, notes H2ouse.org. Depending on the cooler type, the pad can be made of either fiber or rigid-sheet material. Fiber pads may need replacement every year, while a rigid-sheet pad is replaced less often.
An evaporative cooler is an appliance that requires the evaporation of water to cool air. For an evaporative cooler to work, it requires a fan, pads that absorb water, water and a pump. Although an evaporative cooler requires maintenance service at least twice a year, the pads are the parts that are replaced most often. However, there are different types of fiber pads used for these coolers, including Aspen wood, natural fiber and cellulose, notes H2ouse.org. The most commonly used fiber pad is the Aspen filter pad, which is less expensive than the thicker rigid-sheet pad.
Some other types of pads used for evaporative coolers can be spun aluminum and plastic pads. However, because these types are less expensive than Aspen wood pads, they often need replacing more than once a year. The reason for yearly replacement of fiber pads is that evaporative coolers may use hard water, which leaves behind a mineral residue after the water evaporates. This can decrease the cooler's efficiency and also may lead to corrosion of the cooler unit.
Although fiber pads may need replacing on a yearly basis, some other parts that may need occasional replacement can be the water supply system or float valve. For example, water dripping from the cooler constantly can mean a problem with the water supply system and a unit that requires too much water may be related to a faulty float valve.