How Does A Swamp Cooler Work – Your 2022 Guide

| Last Updated: August 21, 2021

Swamp coolers are also known as evaporative coolers as this is the process they use to cool the air.

They are a much cheaper alternative to traditional air conditioning units and this is why many people opt to use them. 

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What are the Parts of a Swamp Cooler?

Swamp coolers have many moving pieces and parts that work together. 

Vibration Absorber

The vibration absorber prevents any vibrations and sounds emitted from the swamp cooler from traveling around your home. They may well be made from an asbestos cloth and connect the supply air ducts in the home to the plenum.

Blower and Blower Motor 

The blower and blower motor are the largest moving parts within your swamp cooler. The motor activates to turn the blower. This forces cooled air contained within the cooling unit to be pushed out. The blower sends the air down the ducts and out into your home.

Evaporative Pads

Wood wool evaporative pads are the primary section of a swamp cooler, the area that actually cools the air. The 2 best substances to use here are Aspen wood wool or honeycomb cooling pads.

The overflow tube prevents the swamp cooler from taking in too much water and drowning the internal components. It helps to drain any excess water remaining in the tank of the cooler.

More: Our full guide to swamp cooler pads

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Ball Float Valve

The ball float valve lies on the surface of the water level within the cooler. As the water level rises, so does the positioning of the float. When the water level reaches a certain point inside the cooler, the float is used to signal to the water supply valve.

Water Supply Valve

The water supply valve is connected to the cooler via a copper tube. On the diagram above, it is labeled as ‘to tap water’. This is what brings the water into the swamp cooler. 

Water Distribution Lines

Water distribution lines carry the water throughout the cooler. They take it from the reservoir at the base up to the top of the cooler. Here the water is released onto the evaporative pads, soaking them. 


The recirculating water pump is found at the base of your swamp cooler. This is connected to the water distribution lines. It draws water from the tank in the cooler and sends it up the lines to the pads.

How Does Evaporation Remove Heat?

As when humans sweat, evaporation will always have a cooling effect. 

During the process of evaporation, liquid molecules are converted to vapors which then disappear from the surface. When the vapors disappear, heat energy is removed from the surface, in this case, the evaporative cooling pads.

The wind increases the effects of evaporative cooling, and this is one of the reasons swamp coolers contain blowers. This is because it drives the evaporation rate up, making the cooler more effective. 

A swamp cooler adds humidity to the air that is being expelled through the ducts in your home. 

Where are Swamp Coolers Most Effective?

They work best in dry and hot climates, such as desert areas of the United States and in India. This is because the coolers incorporate moisture into the air. This means that they would not be very effective in humid climates where there is already an excess of moisture in the air.

The dry air absorbs the moisture, cooling the air as a result. It is important to keep the relative humidity levels in your home below 50%. This refers to the quantity of water vapor in the air relative to how much the maximum capacity the air can hold at any given temperature.

If the relative humidity is too high, the air in your home will feel damp.

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What are the Benefits of Swamp Coolers?

They are much cheaper to run and operate than other more traditional air conditioning units. They are fairly easy to construct yourself if you do not have the money to purchase a cooler outright. Installation costs are about half that of more traditional air conditioning units. 

Swamp coolers are very energy efficient and release hardly any emissions. This makes them a much more eco-friendly option. They do not use any chemical refrigerants which could damage the environment. 

The extra humidity that they release into the air can make dry climates easier to live in. They can relieve sore throats, dry skin, and itchy eyes caused by dry air.

What are the Disadvantages of Swamp Coolers?

They work to lower the temperature of the air, but they are less effective than refrigerated air conditioning. They are also much less effective in humid climates.

If the relative humidity levels in your home are allowed to build up, this can accelerate the rate of corrosion. This means that your electronics could potentially become damaged prematurely, or water could condense inside them and cause damage.

It is important to ensure that the evaporative cooling pads are kept clean and in good condition. This is because they serve as a filter for the air too. Dirty pads could cause bacteria and bad odors to be pushed around your home.

How Does a Swamp Cooler Work?

The water supply valve is connected to the water pipes of your home. This then draws water into the bottom of the tank. This continues to fill until the float reaches its highest level. At this point a signal is sent to close the water supply valve, meaning water stops being drawn in. 

The pump then activates, drawing water up the distribution lines to the top of the cooler.

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At the top, above the cooling pads, the water is released. This water is then sent through the pads, saturating them fully in water.

The blower motor then forces the blower to turn. This pulls warm air from the environment into the cooler, through the cooling pads. As the warm air is pulled through, the moisture in the pads cleans, purifies, and cools it.

The pads also add water molecules to the air, making it less dry. 

The blower then forces the now cooled air out of the swamp cooler. It is pushed through the ductwork in your home and is expelled into the living area.

My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.