Evaporative cooling is a natural process in which heat is applied to change liquid water to a vapor. Heat is removed from the remaining liquid during evaporation. Therefore, it can help cool air as it flows through a medium. An evaporative cooler is an energy-efficient alternative to a central air conditioner that can lower a home’s air temperature by 15℉ to 40℉; it also uses about one-quarter as much energy as a central AC system.¹
How an Evaporative Cooler Works
An evaporative cooler features water-saturated pads. Also known as a swamp cooler, it uses a fan to pass outdoor air over these pads. When the water starts to evaporate, it absorbs heat from the air. Cooled air continues through the system and into your home.
The heat needed to evaporate liquid into water vapor isn’t heat you can feel. The latent heat of evaporation can’t be detected with a thermometer. This heat from the surrounding environment is absorbed into liquid water as it changes state; this energy is contained within the vapor molecules. But the sensible heat, or that which you can feel, of the air, decreases.
For an evaporative cooler to work, its cooling pads must be completely saturated. Its fan and motor must also be properly sized to ensure the amount of airflow accommodates the size of the space it serves. The size of an evaporative cooler is measured in cubic feet per minute (cfm); most models support an airflow capacity of between 3,000 and 25,000 cfm (to relate this to the size of your home, consider the recommended capacity of 20 to 40 air changes per hour).
Is an Evaporative Cooler Suited for My Home?
If you are looking into an evaporative cooling system, you’ll want to consider the following:
- Location: Evaporative coolers add humidity to your home; therefore, they work best in hot climates with low humidity. They also work well in cool, dry areas. Ideally, the wet bulb temperature should be 68℉ or less. But an evaporative cooler can be effective if the wet bulb temperature is below 77℉. On a hot summer day, you’ll want humidity below 25%. The system can work in more humid conditions, but you’ll need to increase airflow to boost cooling capacity, which uses more energy.
- Type of Installation: An evaporative cooler contains a fan that pushes cooled air into a network of air ducts. Some models can blow air to a central location if you have a small home or an open floor plan. In a residential building, the system is often installed on the roof and has a down-flow configuration. However, ground-mounted units are easier to maintain. Or, small, horizontal-flow coolers can be installed in windows to cool an individual room by a few degrees (wheeled portable units are also available).
- Operation: You can operate an evaporative cooler in vent-only mode, in which it serves as a whole-house fan. But with the water pump on, you should be able to set the cooler in one of at least two modes. Air movement, temperature, and humidity are controlled by adjusting the window openings or vents. Two-stage evaporative coolers use a pre-cooler, high-efficiency motors, and more effective cooling pads. They don’t add as much humidity and are often used in hotter climates.
Also, consider that evaporative coolers constantly need water (a concern if water supplies are limited). Sediment and minerals can build up in the unit if not drained and cleaned regularly. The more you use it, the more maintenance it will need, which includes checking the pads, filters, reservoir, and pump at least once every month. The unit’s pads should be changed once or twice a month depending on the frequency of use; some paper/synthetic pads can be cleaned per the manufacturer’s instructions.
Air Stars Finds Efficient Solutions to Improve Home Comfort
Evaporative cooling can improve home comfort depending on a few factors. At Air Stars, we specialize in other high-efficiency HVAC solutions, including ductless air conditioning and heat pumps. Let us evaluate your home and heating and cooling needs. Our team will help find the right system while special offers can help you save. To learn more about our products, maintenance plan, and financing or to schedule a visit, call (503) 832-5779 today.