Many people will start or replace their swamp coolers as the weather warms. It is important to properly install and maintain these systems. Recent technological advances have made it easier to do this.
Swamp coolers cost only one-tenth to one-fourth as much to operate as refrigeration air conditioning and are much cheaper to buy.
An swamp cooler is a simple device that consists of a fan, a pad, and water. To keep the pad moist, a small pump circulates water from the sump (which is part of the cooler cabinet). The fan draws in outside air through the pad to make it more humid and colder. The fan blows this air into the house, forcing warmer air to escape through open windows or into the attic. This is very different from the refrigeration air conditioning which cools the inside of the house and returns it to it.
Swamp coolers have many benefits, but they can also make their installation and operation more difficult. The swamp coolant must be placed outside of the house and ducted inside the house. It should then be frozen protected and isolated from the house in winter.
Swamp coolers cool air by forcing dry air through a moist pad. The entering-air temperature and relative humidity determine the wet-bulb temperature. This is the temperature at which air leaves a 100% effective pad. Swamp cooler pad, which are at the same temperature as the air passing through them, are heat exchangers in heat exchanger theory. The pad’s saturation effectiveness is the temperature at which it gets close to that temperature. This improves with lower airflow rates. The saturation effectiveness of most pads is between 60% and 90%.
Rigid pads should only be washed at winterization. This is when the scale on the pad remains soft and can be removed without causing any damage. Aspen pad coolers should receive major maintenance in spring when they should be replaced.
Sizing Swamp Coolers
Swamp coolers provide more heat than refrigeration air conditioning, so they must be able to deliver more air. The best way to size swamp cools is to get the biggest cooler you can afford. A large swamp cooler with a powerful blower and a strong motor will outperform a smaller cooler with a lower horsepower motor. This is in contrast to air conditioners where the smallest unit is more efficient.
Cooler And More Remote Locations
Swamp coolers are most often mounted on the roof. They have a blower that draws water out of the cooler bottom (known as a down-discharge cooler). Rooftop installations are often the most affordable and offer a good compromise between maintenance costs and first-cost. Rooftop installations can have problems.
- Due to foot traffic and water exposure (from leaking coolers), roof deterioration can occur.
- A sunlit cooler produces slightly warmer air (approximately 1 degree F).
- It is annoying to have to use a ladder for maintenance.
Four pad frames are used in fiber pad down-discharge coolers. This is an improvement on the three pad frames found in side-discharge coolers. Side-discharge coolers can be used on rooftops. These coolers require an extra sheet-metal elbow, but they can often be found lower than a down-discharge one.
There are also other less-common installations.
- Side discharge from the wall to an inner duct. Because these installations must be maintained while on a ladder, they can be very difficult to maintain.
- Ground-mounted up discharge (or side outlet with an upward elbow) These are the easiest to maintain, and they are often shaded naturally. These are my favorite, but dogs can mistake coolers for fire hydrants.
Increasing Air Flow
Swamp coolers with ducts are equipped with a belt drive system that includes an adjustable pulley (also known as a sheave) at the motor. The sheave is secured to the motor shaft by one bolt. The other bolt allows for the sheave’s effective diameter to be adjusted. Motor-belt-blower systems work in the same way as a bicycle drive system. The larger the motor sheave, the faster the blower wheels will turn and the cooler will produce more air.