In low-humidity areas, evaporating water into the air provides a natural and energy-efficient means of cooling. Evaporative coolers, also called swamp coolers, rely on this principle. By passing outdoor air over water-saturated pads, the water in the pads evaporate, reducing the air temperature by 15°- to 40°F-before it is directed into the home. When operating an evaporative cooler, windows are partially opened to allow warm indoor air to escape as it is replaced by cooler air. Unlike central air conditioning systems that recirculate the same air, evaporative coolers provide a steady stream of fresh air into the house. Evaporative coolers cost about one-half as much to install as central air conditioners and use about one-quarter as much energy. However, they require more frequent maintenance than refrigerated air conditioners and they’re only suitable for areas with low humidity. Sizing and Selection Evaporative coolers are rated by the cubic feet per minute (cfm) of air that they deliver to the house. Most models range from 3,000 to 25,000 cfm. Manufacturers recommend providing enough air-moving capacity for 20 to 40 air changes per hour, depending on the climate. Installation Evaporative coolers are installed in one of two ways: the cooler blows air into a central location, or the cooler connects to ductwork, which distributes the air to different rooms. Central-location installations work well for compact houses that are open from room to room. Ducted systems are required for larger houses with hallways and multiple rooms. Most evaporative coolers for residential buildings are installed in a down-flow arrangement on the roof. However, many experts prefer to install ground-mounted horizontal units, which feature easier maintenance and less risk of roof leaks. Small horizontal-flow coolers are installed in windows to cool a room or section of a home. These portable evaporative coolers work well in moderate climates, but may not be able to cool a room adequately in hot climates. Room evaporative coolers are becoming more popular in areas of the western United States with milder summer weather. They can reduce the temperature in a single room by 5° to 15°F. Small, portable evaporative coolers on wheels are now available as well. Although the units have the advantage of portability, their cooling ability is limited by the humidity within your home. Generally, these units will provide only a slight cooling effect. Operation An evaporative cooler should have at least two speeds and a vent-only option. During vent-only operation, the water pump does not operate and the outdoor air is not humidified. This lets you use the evaporative cooler as a whole-house fan in a residential application during mild weather. Control the cooler’s air movement through the house by adjusting window openings. Open the windows or vents on the leeward side of the house to provide 1 to 2 square feet of opening for each 1,000 cfm of cooling capacity. Experiment to find the right windows to open and the correct amount to open them. If the windows are open too far, too much hot air will enter. If the windows are not open far enough, humidity will build up in the home. You can regulate both temperature and humidity by opening windows in the areas you want to cool, and closing windows in unoccupied areas. Where open windows create a security issue, install up-ducts in the ceiling. Up-ducts open to exhaust warm air into the attic as cooler air comes in from the evaporative cooler. Evaporative coolers installed with up-ducts will need additional attic ventilation. Optional filters remove most of the dust from incoming air — an attractive option for homeowners concerned about allergies. Filters can also reduce the tendency of some coolers to pull water droplets from the pads into the blades of the fan. Most evaporative coolers do not have air filters as original equipment, but they can be fitted to the cooler during or after installation. Evaporative Cooler Maintenance Save yourself a lot of work and money by draining and cleaning your evaporative cooler regularly. Build-up of sediment and minerals should be regularly removed. Evaporative coolers need a major cleaning every season, and may need routine maintenance several times during the cooling season. The more a cooler operates, the more maintenance it will need. In hot climates where the cooler operates much of the time, look at the pads, filters, reservoir, and pump at least once a month. Replace the pads at least twice during the cooling season, or as often as once a month during continuous operation. Some paper and synthetic cooler pads can be cleaned with soap and water or a weak acid according to manufacturer’s instructions. Filters should be cleaned when the pads are changed or cleaned. Be sure to disconnect the electricity to the unit before servicing it. Two-Stage Evaporative Coolers Two-stage evaporative coolers are newer and even more efficient. They use a pre-cooler, more effective pads, and more efficient motors, and don’t add as much humidity to the home as single-stage evaporative coolers. Because of their added expense, they are most often used in areas where daytime temperatures frequently exceed 100°F. Drawbacks of Evaporative Coolers Evaporative coolers should not be used in humid climates because they add humidity to the air in your home. Also, they do not cool your house down as low as an air conditioner would, and they require simple maintenance about once a month. If the evaporative cooler is installed on the roof, there is some roof deterioration caused by routine maintenance trips. A sunlit rooftop cooler will be about 1°F less effective than a shaded cooler. Rooftop maintenance also requires using a ladder, which may be an inconvenience. By their nature, evaporative coolers also continually use water. In areas with limited water supplies, homeowners may be concerned about the water-use impact of adding an evaporative cooler. Subscribe to Energy Saver Updates Subscribe to receive updates from Energy Saver, including new blogs, updated content, and seasonal energy saving tips for consumers and homeowners.

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Home Cooling Blogs THE MATERIAL CONTAINED IN THIS ARTICLE IS PROVIDED FOR GENERAL INFORMATION PURPOSES ONLY AND DOES NOT CONSTITUTE PROFESSIONAL ADVICE.LANDMARK HOME WARRANTY DOES NOT PURPORT TO BE A SUBJECT MATTER EXPERT WITH REGARD TO THIS MATERIAL, AND YOU SHOULD CONDUCT YOUR OWN RESEARCH AND/OR SEEK THE ADVICE OF APPROPRIATELY QUALIFIED PROFESSIONALS WITH REGARD TO YOUR SPECIFIC CIRCUMSTANCES BEFORE YOU TAKE ACTION. LANDMARK HOME WARRANTY ASSUMES NO RESPONSIBILITY, AND SPECIFICALLY DISCLAIMS ALL LIABILITY, FOR YOUR USE OF ANY AND ALL INFORMATION CONTAINED HEREIN. Learn how a swamp cooler works and cools your home with these animations and diagram. Have you ever traveled to a place with high humidity? You may have found your hair curled, your skin was softer, but you seemed to sweat a lot more. Your body used the moisture in the air to make you sweat, and cool you down; a process called evaporative cooling. This same principle is used when it comes to swamp coolers. Swamp coolers are prevalent in warm, dry areas, such as Utah, Nevada and Arizona, where there’s less moisture in the air, and evaporative cooling can work by adding moisture in the air. But how does a swamp cooler actually work? The following animations will give you a better idea of what’s happening in that machine that makes you comfortable in those warm summer months. Getting ready for winter? Click here to learn how to prep your swamp cooler for the colder months. Learn how to get your swamp cooler ready for the winter months. A swamp cooler uses moisture to cool air. A swamp cooler (which is also called an evaporative air conditioner) works by taking warm outside air through wet evaporative cooler pads, effectively cooling the air. The cold air is then blown into a home by a blower motor through a vent. The main parts of a swamp cooler can be found in the diagram below. A swamp cooler diagram showing the internal parts of a swamp cooler and how it operates to cool your home. Download these diagrams and animations of a swamp cooler and how it works.

The Parts that Make Up an Evaporative Cooler:

Water Supply Valve

This valve is found inside of your home, generally where your water heater is connected to the rest of your plumbing. This valve is connected to your swamp cooler by a copper tube. It brings water into the swamp cooler. Without this valve, the swamp cooler cannot work.


The evaporative cooler float is found on the bottom of the swamp cooler. When the water in the bottom of the swamp cooler reaches a certain level, the float rises on top of the water and shuts off the water supply valve. If this float stops working, the swamp cooler may not work or may overflow.


The swamp cooler’s pump is also found on the bottom of the unit. It pumps the water through the water distribution lines, keeping the evaporative pads wet.

Evaporative Pads

The evaporative cooling pads line the inside of the swamp cooler. They have to be wet for the swamp cooler to work properly. The clean and cool the air.

Blower and Blower Motor

The blower motor turns the blower, which brings cool air into the ductwork and forces it out of a home, cooling the air.

How Does a Swamp Cooler Work?

A swamp cooler works to cool the air in your home with four main steps. These are:

  1. Water Supply Valve Brings Water into Bottom of Swamp Cooler

A swamp cooler begins the cooling process by filling with water. Download these diagrams and animations of a swamp cooler and how it works. When you turn the dial of your swamp cooler to the «on» position, the water supply valve brings water into the bottom of the swamp cooler. The water continues to pour into the swamp cooler until the float, which is sitting on top of the water, reaches a certain level. This signals the water supply valve to turn off.

  1. The Pump Brings Water to the Evaporative Cooler Pads

The swamp cooler's pump brings the water from the bottom of the evaporative cooler up into the pads. Download these diagrams and animations of a swamp cooler and how it works. After there is enough water in the bottom of the evaporative cooler, the pump begins to pull water through the water distribution lines. These water distribution lines are located at the top of the evaporative pads and pour water through them. If the homeowner feels that the air isn’t cool enough, they can turn their swamp cooler’s switch to «pump» to pump more water into the evaporative pads.

  1. Warm Air is Pulled Through Evaporative Cooler Pads

The swamp cooler takes warm air through the wet pad and cools it, then blows it throughout the home. Download these diagrams and animations of a swamp cooler and how it works. After the evaporative pads have water on them, the blower motor begins pulling warm air into the swamp cooler, through the pads. As the warm air goes through the pads, the moisture cools the air, and cleans it. This process is called evaporative cooling. This works the same way when you are exercising, and sweat, and then have a fan blow on you, cooling your skin.

  1. Blower Forces Cool Through Vent, Cooling Home

After the air is pulled through the evaporative pads and cooled, the blower takes the cooled air and forces it through the ductwork and vent, and into the house. Here is the full process of the swamp cooler cooling a home animated below: The full process of how a swamp cooler works to cool your home. Download these diagrams and animations of a swamp cooler and how it works. ​​​​​​​

Did you know a Home Warranty Covers Swamp Coolers?

Unfortunately, each of these parts of a swamp cooler has a lifespan; they don’t last forever. Eventually, the mechanical parts of your evaporative cooler will get worn out and fail. When this happens, make sure your home is covered by a home warranty. Home warranties cover the systems and appliances in your home for a premium of $300 to $600 a year. When something breaks down, you pay a small service call fee for it to be repaired and replaced, provided it failed from normal wear and tear and is covered under the home warranty contract. Click to learn more about what a home warranty is, or what’s covered with a home warranty. You can also learn about home warranties on our main page. Evaporative cooling is one of the best possible ways to save electricity in the summer when temperatures rise to their peaks and your home AC just can’t keep up. Swamp Cooler is the popular name for an evaporative style cooling system. There are swamp coolers big enough to cool an entire home and portable swamp coolers that are perfect for cooling one room at a time. There are even entirely non-powered swamp coolers that you can take with you on summer camping trips to beat the heat inside your tent. That all sounds pretty great, right? Before you bust out a brand new swamp cooler in your living room or at your campsite, it’s important to understand how they work. Swamp coolers are not like normal AC units and they don’t even use the same technology to make a room cooler.


The first thing to understand is that swamp coolers are nothing like a traditional AC. Normal ACs use a ton of electricity to keep refrigerant running through condenser coils which together create the cold that cools your air. Swamp coolers, on the other hand, work through the pure cooling power of evaporation. In fact, swamp coolers don’t even have to run the fan, but the fan helps to circulate the now-cooled air. The way a swamp cooler works is the same way sweat works to cool down your skin. When water is evaporated into the air, it takes a certain amount of heat out of the air at the same time and replaces it with an aerated water droplet. It does this by soaking cooling pads in water and waiting for the pads to begin to dry via evaporation. The drying process really does cool down the air around the swamp cooler and a small fan can spread that cool air around.


However, because swamp coolers work by adding water molecules to the air, they are also most effective in lower humidity environments. The drier your hot summer air is, the more powerful a swamp cooler can become. The reason for this is because dry air absorbs moisture through evaporation easier, causing the air to give up heat in return for moisture. The moist air not only cools the ambient temperature of the room, it can also act as a humidifier making dry summers more bearable and less damaging to the skin. However, you can still use your swamp cooler in regions that tend toward humidity and on days with higher humidity than usual. Swamp coolers work in humidity up to about 70 percent. However, you may begin to feel muggy before the air reaches this saturation with or without a swamp cooler.


Now let’s move onto what you really came here for: A quick and comprehensive guide on putting your swamp cooler to use.


Start by filling the tank of your evaporative cooler. Whether you are camping or have the cooler plugged in next to your couch to cool you directly, it can’t work without water to soak up and evaporate. It’s best to start with cool tap water, about 50-degree water. When that cool water evaporates, it will further cool the air around your swamp cooler and the fan cal blow that cooled air directly onto you. Ice can offer a temporary boost to the coolth but does not actually increase the efficiency of the swamp cooler for cooling a room. In fact, because ice can’t absorb and evaporate without melting first, it can serve to slow down the cooling process overall.


Once the reservoir is full, give your swamp cooler a little time for the pads to soak up the water before turning on the fan. This is how the cooler works. The pads wick moisture up from the reservoir then act as fins exposed to the air to promote cooling evaporation. If you start the fan before the pads have become moist and ready to evaporate, you’re just blowing around hot air. But if you wait about 5 – 15 minutes before filling, the cooler will be ready to go.


Some swamp cooler users swear by priming the pads. This is done by pouring a little water over the pads to moisten them at the beginning of a cooling session. Priming the pads gets them initially wet so that the evaporation can begin. It also makes it easier and faster for the pads to wick moisture up from the reservoir as it gets started.


Evaporative coolers are not as powerful as their electricity-hungry counterparts, but they can make you feel a lot cooler when used correctly. One of the best ways to optimize your swamp cooler is to point it at exactly where you want the cooling to happen. Swamp coolers are often pointed at the couch or seating area to keep you and your guests cool or at the dining room table for a cool summer dinnertime.


One interesting difference between swamp coolers and AC is that a swamp cooler can actually work better if you open the windows a bit. The reason for this, again, is the humidity. If the cooler is efficient, it will put a significant amount of cool moisture into the air which will, in turn, raise the humidity and lower the cooler’s efficiency. To keep your swamp cooler cooling, consider cracking a window to let out the current humid air and provide new dry air for the cooler to evaporate water into.


Alternately, if the day is just too hot to crack the windows or you’re experiencing a hot muggy summer, a dehumidifier can do the trick. Dehumidifiers work in the opposite way that swamp coolers do. They pull water moisture out of the air and slowly fill a tank reservoir that will need to be emptied. The dehumidifier will then blow out a steady stream of drier air and lower the humidity in the surrounding room. Paired up, a dehumidifier can significantly improve the cooling efficiency of a swamp cooler on a humid day or inside a sealed house. For best results, point the dehumidifier vent at the swamp cooler intakes so that the driest air is being used to create more lovely coolness. All told, a swamp cooler next to a dehumidifier still use less electricity than a hard-working AC trying to fight off the summer heat. Using a swamp cooler is not nearly as complicated as you might think. Boiled down, all you need to do is fill, wait or prime the pads, then point the fan at wherever you want the cool air to go. If you have trouble, test the humidity and increase airflow or use a dehumidifier paired up to manage the moisture. For more information on how to use your swamp cooler or other methods to stay cool this summer, contact us today! Image of swamp cooler on roof standard-swamp-cooler
Swamp cooling or evaporative cooling, is a popular, cost effective way to cool your home here in the southwest. Swamp cooling works best in the hot dry climates like New Mexico. Basic swamp cooler function starts with a pan filled with water that will automatically fill as water evaporates. The water is pumped from the pan to a pad which absorbs the water and drains back into the pan. The wet pad filters the air that is drawn from outside by a blower motor and pushed into the house through a duct. As the air moves through the wet pad it cools down and gains humidity (this is where the evaporation happens). All the space in the home will be conditioned by cooler air between supply and return. Supply is the air coming out of the registers (vents) in the house, and the return is an open window or door. The air moving through the house will absorb some of the heat and push some outside. The end result is a cooler and more manageable living condition during a hot dry day.

How To Operate A Swamp Cooler

    1. Locate the swamp cooler control –The swamp cooler control is a panel like any of the types of controllers pictured below. There are also several variations of these as well. It’s also important to note that there are manual controllers and digital thermostat controllers. (See examples below).

swamp-cooler-control swamp-cooler-dial-control swamp-cooler-thermostat

  1. Turn the pump on – The first step is to turn the pump on to wet the pads before turning on the fan. If you have a manual control always turn the pump on for approximately 5 minutes to ensure the pads get wet enough. Then you also turn on the fan to either high or low to begin circulating cool air through your home. If you have a digital thermostat control you can set the pump and fan to turn on automatically by setting a temperature threshold that will turn on the cooler when your home reaches a certain temperature.
  2. Always open a window(s) – when running your swamp cooler. As swamp coolers push cool air through the duct system in your home that hot air gets pushed out through open windows. This is opposite of refrigerated air conditioning where you keep your windows and doors shut when the air conditioner is on.

How to get the most out of your swamp cooler

Here are some quick tips along with a video that shows you what you can do to ensure that you get the coolest temperatures from your swamp cooler. If you don’t feel comfortable doing any of these or getting up on your roof, please contact a professional to evaluate your swamp cooler.

  • Make sure your pads are wet – if you feel that your swamp cooler isn’t cooling your home, the first step it to check if your pads are getting wet. If the pads aren’t wet your swamp cooler will just blow hot air from outside into your home. If your pads aren’t getting wet you may have an issue. You could have problems with your pump or clogged water lines.
  • Do you have enough relief air? – Check to ensure you have enough windows open in your home to push the hot air out. Also, make sure you open windows in the hottest part of the house to bring cooler air into those rooms.
  • Get a digital thermostat – a digital thermostat will allow you to set a temperature for your swamp cooler to automatically turn on and off to gain better control of the temperature in your home.
  • Humidity – A swamp cooler’s cooling effectiveness relies on humidity levels outside. If the humidity levels rise too high your cooler will have a harder time lowering your home’s indoor temperature. See the video below to learn more about humidity levels and efficiency temperatures.

If you continue to have problems after performing these tips, it may be time to call a professional to repair your swamp cooler.

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