Evaporative Cooling

The effective way to cool your home

Evaporative Cooling

How Evaporative Cooling Works

An evaporative cooler is essentially a large fan with water-moistened pads in front of it. The fan draws warm outside air through the porous pads and blows the now-cooled air throughout the house.

Small distribution lines supply water to the top of the pads. Water soaks the pads and, thanks to gravity, trickles through them to collect in a sump at the bottom of the cooler. A small recirculating water pump sends the collected water back to the top of the pads. Since water is continually lost through evaporation, a float valve – much like the one that controls the water in a toilet tank – adds water to the sump when the level gets low. Under normal conditions, an evaporative cooler can use between 3 to 15 gallons of water a day. A large fan draws air through the pads, where evaporation drops the temperature approximately 20 degrees. The fan then blows this cooled air into the house.

Normal air conditioning is a closed system, taking air from inside a house and recycling it. For air conditioning to function properly, doors and windows should be closed. Evaporative cooling, however, takes air from outside the house. For evaporative cooling to work properly, the cooled outside air must be allowed to escape. By choosing which doors or windows in your home you leave open, you can to help direct the flow of cooled air to areas where it is needed.


  • Low maintenance cost
  • Low initial cost
  • Replaces stale air with fresh filtered air
  • Brings the outdoors in
  • Great for those on a budget

How Well Do Evaporative Coolers Cool?

The temperature of air coming out of an evaporative cooler obviously depends on the temperature and the humidity of the air going in. The main drawback of evaporative coolers is that they depend on dry outside air to operate effectively. On hot, muggy days in the summer, however, evaporative coolers will blow hot, humid, soggy air into the house.

In addition to the dropping the temperature of the air, evaporative cooling offers an additional cooling benefit. The constant movement of the air created by the blower – the cooling breeze it creates, if you will – makes the occupants of a room feel 4 to 6 degrees cooler than the actual temperature. This is the same effect you feel when you turn on a ceiling fan or a simple window fan. For this reason, the “effective temperature” created by an evaporative cooler will feel 4 to 6 degrees cooler than temperatures shown on the thermostat.

An added benefit of evaporative cooling is that it works best in the hottest time of the day. As the temperature outside increases as the sun climbs, the humidity normally drops, which makes evaporative cooling more effective.

For a swamp cooler to effectively cool, it must be the proper size for the job. A small unit will not adequately cool a large-sized house.

Benefits of Evaporative Cooling

  • Evaporative coolers are very energy efficient, using as much as 75 percent less electricity as air conditioning does.
  • Because the technology is simpler, an evaporative cooler costs about half as much as an air conditioner that will cool the same sized area.
  • Evaporative coolers operate on 240-volt electricity, which means they don’t need special high-amperage circuits like many air conditioners do, it can be plugged into a nearby outlet.
  • Many people appreciate the fact that evaporative cooling adds moisture to the air, which helps to keep wood furniture and fabrics from drying out. The moist pads through which the outside air flows are also fairly efficient air filters, trapping some dust and pollen. Since the pads are continually wetted, trapped particles are flushed out and trapped in the bottom of the cooler.
  • Evaporative coolers cool outside air and blow it into the house, therefore, to work effectively they need at least one window open. The cooled outside air vents through open windows or doors, pushing out hot inside air and any smoke, odors and pollution that may be present. With evaporative cooling, a complete air change in a home occurs every one-to-three minutes. This flow of fresh air means that evaporative coolers can be operated without using the water pump to replace warm stale air with cooler night time air, much like a whole house fan does. That’s an added benefit.
  • For the most part, evaporative cooling doesn’t require as much ductwork as air conditioning. For a newly installed system, a short duct can direct the cooled air to a central point in the house. From there, air can be directed through the various rooms by simply opening and closing doors and windows to allow the cooled air to flow.

When should I have my Cooler serviced?

To ensure that your Evaporative cooler continues to operate at peak efficiency, it should be serviced at two year intervals by an authorised person trained in the service of coolers. Colbycool is authorised to service all evaporative coolers.

This service of the cooler unit will include all maintenance and adjustments required to the following components to ensure your cooler runs at its peak efficiency:

  • Trough
  • Sensors
  • Fan and Pump Assembly
  • Pads and Water Distribution

Please note that to maintain your warranty, many manufacturers now require regular servicing to be conducted by an authorised person trained in the service of Evaporative Coolers.