Do Evaporative Coolers Work?Written by Duncan under Evaporative Coolers | 2 Comments
The answer to this question is “Yes”, evaporative coolers will reduce the temperature in a room, but the effectiveness of an evaporative cooler will depend on how you use it.
If you put it in a room with the windows and doors shut, it isn’t going to do much for you apart from circulate air, much the same as a fan, and increase the humidity. In order for evaporative coolers to really make a difference to the temperature in a room, the room needs to be well ventilated.
For every litre of moisture added to an atmosphere approximately 650W of cooling will take place. However, the higher the humidity, the less moisture will be evaporated as air can only hold so much water at any given temperature. As the air becomes more humid, the cooling effect will be reduced as the air will accept less and less moisture.
So in order to make an evaporative cooler really effective, you have to maintain a low room humidity for the moisture to evaporate and produce the cooling effect. You do this by ensuring the room’s windows and doors are open, and the room has plenty of air flowing through it. As the water in the cooler evaporates, cooling the air and raising its humidity, the humid cool air is pushed out of the room and replaced with warm dry air, which is then cooled and humidified all over again.
By maintaining a good flow of air through a room, the evaporative cooler will work at maximum efficiency.
If possible it is always advisable to position an evaporative cooler by an open window or door so the air is cooled as it enters the room, and have another window or door open on the other side of the room. The internal fan within the cooler will drag air into the room, creating a positive pressure, which will in turn push air out through other open windows or doors.
As well as the evaporative cooling taking place, this simple ventilation will also add to the cooling of a room making it feel more comfortable.
Some evaporative coolers have the ability to add ice to the water tank or incorporate some form of frozen element, which can be put in a freezer and then inserted into the unit. This can significantly increase the cooling effect of the unit.
However, by doing this you do lose some of the low energy benefits of evaporative cooling. Evaporative cooling has much lower running costs than refrigerant based portable air conditioners. However, if you factor in the energy used to chill the ice or freezer element, the running costs will start to increase (probably nowhere near the same level as air con though - although I haven’t done the sums. Anyone wanting to please feel free to leave a comment below and I’ll publish them here).
You do still have the major cost benefit of evaporative coolers being much cheaper to buy initially then portable air conditioners.