How Swamp Coolers Work

A little science talk helps you appreciate how an evaporative cooler works and for which climates it’s best suited. Evaporation is an endothermic process, which means it absorbs heat from the surroundings in order to effect a change of state from liquid to vapor. Particles in a vapor are in a higher energy state than those in a liquid, so energy is required for evaporation to occur. That energy comes in the form of heat from the surroundings. In other words, when a liquid evaporates, the immediate environment become cooler. The process doesn’t create cool air—it creates air that is less warm. It’s a subtle distinction, but an important one.

Air Conditioners rely on this principle, but the substance that evaporates is a specially formulated refrigerant sealed in a system of coils. A compressor circulates this refrigerant as a liquid through the condenser coils and forces it through a tiny aperture into the evaporative coils. As it vaporizes, it draws heat from the air around the coils.

Evaporative coolers—also known as swamp coolers—employ the same principle, but instead of a refrigerant in a sealed system, they stream plain old water onto an absorbent pad, from where it evaporates. Anyone who has ever sweated knows that evaporating water cools the surrounding air. The same principle applies with an evaporative cooler A fan inside the unit blows the cool air through a grid or duct system and into the living space. This process is especially suited for hot arid climates, like the Colorado Springs, CO area. They do require more maintenance than air conditioners, but not much.

Swamp Cooler Routine Maintenance

An evaporative cooler is not a sealed system, and the water that circulates through the filter pad gets dirty. It may get contaminated by bacteria, which become airborne as the fan blows through the pad. You don’t have to worry about water contamination if you have a rooftop unit connected to a supply pipe and a drain, because fresh water is always circulating through the pads.

Although the air circulating through the filter pads is a natural mold and mildew deterrent, some mold is bound to get a foothold during the course of a hot summer. Allowing the filter to dry out completely when you change the water is a good way to keep it under control, but to be on the safe side, it’s best to remove the filter and clean it periodically. When the filter is out, we will clean the inside of the filter compartment, as well as the water reservoir.

Every few years it’s a good idea to disassemble the fan blades and give them a deep cleaning, along with the fan housing. The water tubes inside the unit should also be disassembled and soaked, to keep them free of mold and other debris.

Swamp Cooler Beginning and End of Season Process

You probably don’t need your evaporative cooler during the winter, so before you put it into hibernation, it needs to be drained completely and the filter pads removed. We will wipe down the interior of the unit or wash it with soap and water, then replace the pads when everything has dried out. We then unplug the unit or switch off the circuit breaker to ensure it doesn’t start up when it’s empty of water.

When you start up the unit in the spring, it’s a good idea to have the pad removed again and inspected. This is the best time of year to replace the pad, if necessary. We recommend replacing the pads at least twice a year, and we highly recommend that practice if you keep your unit running constantly. High-quality pads may not need replacing quite that frequently, but if inspection reveals damage or cracking to any part of the pad, then it should be replaced.

The fan rotors and motor need periodic lubrication to keep them in good working order. The best time to do this is in the spring when you’re restarting the unit. We will clean the fan blades and the motor housing with a damp rag, and spray lubricant into the motor shaft. We’ll also a replace the fan filter, if necessary.