Evaporative coolers (or swamp coolers) are cheaper to buy than air conditioners – and use less energy – so it’s no wonder they are an appealing choice for anyone who wants to save money while keeping cool.
What is not so cool is when your evaporative cooler doesn’t actually make you cooler – in fact, this can make you a little hot under the collar. So to help avert any “heated crises” we’ve put together a few hints and troubleshooting ideas to help you get more out of your unit.
Humidity is the Bane of Evaporation
Evaporative cooling works when water evaporates, using a little bit of the heat in the air as energy as fuel for the transformation from water to vapor. The faster the water evaporates, the more heat is used up, lowering the temperature in the surrounding area.
When the humidity is high, though, the air is already filled with moisture, and evaporation is slow to happen. That’s why humid weather is so much more uncomfortable than dry heat – the sweat your body produces sticks to your skin instead of evaporating and cooling you down. When it’s humid, an evaporative cooler turns into little more than a fancy looking fan.
Usually, we do not recommend swamp coolers for places that experience a lot of humidity in the summer, because they just aren’t effective. Here’s one exception, however – you can use an evaporative cooler as a supplement to central air conditioning. How does that work? Well, part of an air conditioner’s magic is that it dehumidifies the air – dehumidification takes place even if you run your AC at fairly high temperatures. So you can set your central AC at 80°F or higher – which will save you a bundle on whole-house cooling costs – and use a portable evaporative cooler to lower the temperature in the one or two rooms you’re actually using.
Everyone Needs to Vent
With an air conditioner, a room or building needs to be closed up tight for it to be effective. The opposite is true with a swamp cooler, which rely on a consistent stream of fresh air in order to work.
If you find your portable evaporative cooler isn’t actually cooling, make sure it is positioned near an open window or door. An open window on the opposite side of the room also helps by creating a cross breeze that draws hot air out. Usually, 1 or 2 square feet per 1,000 CFM of cooling capacity is sufficient to allow hot air and humidity to be pushed outside. You can experiment and adjust which windows and how wide they are open to control the amount of cooling delivered.
Ice, Ice, Baby
You may have seen the pictures floating around the internet of “redneck air conditioners” – usually a variation of a fan attached to a cooler full of ice. The fan is used to circulate the cold air coming from the ice around the room.
Because ice makes air colder, it seems reasonable that adding ice to your evaporative cooler increase your cooling capacity. In fact, many coolers feature special ice compartments and gel ice packs to help generate this cold air effect.
In actual practice, adding ice to your swamp cooler will only have a limited effect. Yes, cold air radiating from the ice will be blown out by the fan, so you’ll get an added boost if you’re standing right in front of the unit. But the ice will not improve the rate of evaporation, or actually remove heat from the air the way evaporation does. In fact, it might actually hamper the cooling process – keep in mind that water has to heat up in order to evaporate. If the water is too cold, it might drip out of the cooling pads before it has time to heat sufficiently for evaporation to take place.
Ultimately, the combination of temperature and humidity in the ambient air will dictate how effective ice is in boosting cooling power. If you are having trouble getting much cold air out of your cooler, try replacing the ice and cold water with room temperature water (never hot water!) and see if the effect is improved.
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