Beyond A/C: alternatives in cooling
There are other ways of cooling the interiors and exteriors of our homes other than using air conditioners – mechanical devices that use electricity to cool coils of metal and pump hot air over them, thus cooling the airflow.
Such air conditioning became common shortly after World War II, and most public places in the temperate zones are air conditioned. The same goes for many homes in the United States.
Air conditioning is expensive, and there are many who do not care for it.
Some forms of air cooling date back to the ancient Egyptians and Romans, when wet reed mats were hung in doorways to cool incoming air. Humidity was also increased – nice if you live in a desert or in the Great Basin of Nevada.
The same principle is used today in evaporative or “swamp coolers,” which use an electric fan to force air through a wet plastic mat. Water is pooled into the base of the cooler then pumped up the mat; the outgoing air is cooler as the water absorbs heat from the air by evaporation. Cooling in the Great Basin area is as much as 20 degrees when the ambient air is hot enough.
But there are two problems with swamp coolers: the water continually needs to be replenished, and there must be two openings in the room being cooled. One allows for warmer, drier outside air to enter the house, the other to exhaust air to make room for more.
Swamp coolers are for modest installations, such as home offices. But they can make a living room more comfy. And big ones can do a lot to make life more comfortable.
Swamp coolers come in all kinds of sizes. The most common are small, portable units not much larger than a plain box fan. Others are great, hulking, fixed beasts rivaling refrigerators in size.
You can hook up a fixed swamp cooler to a water line that automatically keeps the tank full. Or you can fill it with a bucket; most can hold around five gallons. Some have drainage systems that remove water when it has become loaded with salts and minerals. Others require you do that at intervals.
As water evaporates from the pads, dissolved salts and minerals are left behind. This concentration eventually causes scale to precipitate out on the pads, making them hard and nonabsorbent. To prevent this, concentrated salts are removed from some coolers via a “bleed-off” mechanism.
In some cases, a continual stream of water is removed; in other cases, a manual valve is opened occasionally to drain. Newer models have timers which dump the contents of the water pan after a set number of hours.
This bled-off water can be put to some uses, despite its elevated salinity and hardness. It can be diverted directly to salt-tolerant species such as turf, or stored then diluted with tap water or rainwater, thereby reducing its salinity.
Swamp coolers run from $99 for a portable unit good for about 200 square feet to the giants that try to do the house for $4,000 and up.
Folks differ on why it’s called a swamp cooler. Some say because it makes the house feel like a muggy swamp, but that’s only when the late summer rains come and the cooler is less efficient. On dry days, a swamp cooler works fine. In high-humidity areas, they don’t work at all because the water does not evaporate appreciably.
Swamp coolers are relatively inexpensive to operate, use a quarter as much electricity as a refrigerated unit, are easy to maintain by the average do-it-yourselfer, and add a comfortable level of humidity to dry desert air.
Electric fans create a wind that cools you for a couple of reasons. The warmth of your body heats a thin layer of air on your skin. Wind blows the warm air away, and you feel cooler. A breeze also blows water vapor away from your skin, which lowers the humidity, increases the evaporation rate, and cools you. The stronger the wind, the greater the evaporation.
Fans come in just about every size, from small tabletop rotating ones to giant industrial drum fans that go for around $500.
There’s a form of evaporative cooler for the outdoors. This consists of a stretch of plastic tubing with small nozzles about every 18.
The tubing is attached to an outside faucet. When the water is turned on, mist billows out of the nozzles. The hot air vaporizes the mist and cools the air temperature.
This system works best for an enclosed patio with no roof. The cost is modest, less than $50 for a unit that spans two sides of a patio.
If you own an evaporative cooler, here are some tips to help you save water and energy.
1. Use a closed system without bleed-off lines or dump pumps. This approach uses about three gallons of water per hour; other systems use between five and 10 gallons of water. Periodically, you’ll need to clean away mineral buildup inside the cooler.
2. Some systems use bleed-off lines, which allow water and sediment to be drained from the system periodically. This approach typically triples the water use so it’s important to adjust the lines to release as little as possible.
3. Power cleaners, or “dump pumps,” are an alternative to bleed-off lines. While they’re less efficient than a totally closed system, they’re more water efficient than the typical bleed-off lines. These devices are programmed to automatically discard the water in the reservoir tray after a specified time. They use approximately five gallons of water per hour of operation.
4. During the spring and fall, operate the cooler fan without the water pump to draw in cool nighttime air.
5. Wait until it’s at least 85 degrees outside before turning on your swamp cooler and you’ll use 50 percent less water.