The most energy efficient means of cooling is through evaporation. Evaporative coolers (or swamp coolers) are cost effective alternatives to conventional air cooling systems. These coolers cool indoor spaces using water and air circulation, which is similar to the perspiration process. There are ways to ensure the swamp cooler is efficient and keeps performing at its peak:
1. Select the appropriately sized cooler for the area to be cooled based on the cubic feet per minute (CFM) of air the unit can pump. Most units provide the information in the owner’s manual or directly on the unit.
Use the following formula to calculate the CFM:
CFM = the home’s square foot area X the average ceiling height / 2 air changes/min.
Open windows (approx. 300mm – more for larger rooms) to ensure blown air from the cooler is allowed to escape, so fresh air can enter. Openings should nor face the wind.
A security relief grille may be installed in the ceiling as an alternative to opening windows.
2. Adjust grille louvers to direct the air down and so it circulates. Rotate the grille segments to direct the air where desired / needed.
3. Balance the air flow so humidity is minimised. The amount of incoming pumped air should be the same volume of air outflow. This can be achieved by opening windows or by installing ducts in each room.
4. Window heat load increases the size of the cooler that will be needed. Undersized coolers will not perform to their maximum efficiency. When a new building is designed, windows should be oriented on the north side of the building, with shading. Windows should not face west. The next best window location is the south side of the building with massive amounts of vertical shading provided.
External shade and reflective or thermal glass significantly reduce the heat load. Verandas and external bamboo blinds or roller shutters are effective.
5. Coolers can effectively ventilate without cooling. The manufacturer’s manual should be referred to, to determine the correct control settings. In this instance, the fan runs but the pump does not. Performance can be maximised in this manner when it is cool outside but it is desired to cool down the warm building. This method can also alleviate smells or dry freshly painted rooms or mopped floors.
6. Evaporative coolers without thermostats generally have separate fan and pump switches. If there is no thermostat, the pump should be run several minutes to saturate the cooler pads before the fan is turned on. For greater efficiency, evaporative cooler thermostats that automatically turn the cooler off when the cooled air reaches the desired temp, may be purchased at a local hardware store.
7. Finally, evaporative cooler cleaning and maintenance are necessary to ensure peak performance. Regular cleaning should be performed minimally at the beginning and end of the cooling season. The cooler must be cleaned annually regardless if it has operated in dry tank mode. Commercial installations, or coolers used in areas where the water has too many minerals or impurities in it, must be cleaned and maintained more often.