Window Air Conditioner Review
Cooling one's home in the summer is one of the essential tasks of maintaining a livable home; in the old days - before the 1930s, the only ways to do this involved opening windows and doors and setting up a breezeway, or having someone wave a fan over you.
With the invention of the electric motor, fans no longer required someone to wave them, and the climate control revolution had begun.
What Is Evaporative Air Conditioning?
The concept of a fan circulating air is the fundamental principle of the evaporative cooler - a fan pulls in warm are, runs it by pads impregnated with water. The water evaporates in the warm are (by the same mechanism that will make your towels dry out) and cools by as much as 20 degrees Fahrenheit. The cooled air is then forced out of the cooler and into the room.Called "swamp coolers", evaporative coolers have been around since the late 1930s, and been a staple of home construction in places with dry climates for half a century.
By contrast, an air conditioner uses a compressor to compress a refrigerant; this heats it up. It's then circulated to the inside of the house, where it's allowed to expand through coils. When a gas expands, it cools off by Boyle's constant gas law.
The gas warms up through this process and is run through the outside end of the cycle, compressed and the whole thing runs again.
How Evaporative Coolers Work
Evaporative coolers and air conditioners both use the phase change of a gas to do their function; the difference is the working fluid. Commercial refrigerants are all chemicals with a very interesting range of compressive and expansion properties.Water has a much narrower range of liquid to gas transition, but it's ubiquitous, and is naturally a liquid at room temperature without running a compressor. However, the water escapes the system in normal operation; air conditioning units need refrigerant recharges every 4-10 years depending on the usage cycle.
The evaporative cooler is an open cycle cooling system, while the air conditioner is a closed cycle cooling system. Because of an evaporative cooler's open cycle system, it runs through water - roughly 3-10 gallons per day, depending on the relative humidity. Evaporative coolers don't work well in humid climates; in fact, they don't work much at all if the humidity goes past 30%.
Evaporative coolers also require a way to pull air from outside the house into the cooler; this means that you need to leave a window open, or have an airway open for the evaporative cooler to run.
Evaporative Air Conditioning Advantages
With all those drawbacks, the evaporative cooler has some major advantages to go with it. The first is that without having to run a compressor, evaporative coolers use as little as one fifth to one sixth of the energy that a dedicated air conditioner does.The second is that by adding humidity to the air, the perceived amount of chill can be much greater.
They're also refrigerant free; if you want to reduce the amount of refrigerants released into the atmosphere (which has been cited as a cause for ozone depletion in the stratosphere), then an evaporative cooler is the way to go - they're absolutely 'greener', though refrigerant leaks in air conditioning units made since the 1990s have been reduced to less than 1% of their former rate.
Additional benefits of the way evaporative coolers work is that by increasing the humidity of the room, you're also making sure that your linens and furniture last longer between dustings and coatings with furniture polish.
Nothing causes wooden furniture to age faster than regular changes in humidity, which causes the wood to swell and contract, eventually breaking the joins and causing the finish to dull.
Evaporative Air Conditioning Disadvantages
Evaporative coolers aren't good for keeping outdoor allergens outside the home; they can also be a source of indoor allergens if the pads (typically alderwood) aren't changed every other season, and gather mildew or worse.On the flip side, while you may need a separate filter for air conditioned air, evaporative coolers make good traps for airborne bacterium.
Evaporative coolers are also much lower maintenance in the short and medium term (and almost maintenance free in the long term). When an air conditioning system breaks down, you have to call in an experienced Heating and Air Conditioning specialist to go through the duct works, check for leaks and top off the refrigerants.
Evaporative coolers work by a float valve in; the only moving parts are a very simple pump and a circulatory fan; someone with a bit of mechanical expertise can fix one in an afternoon if it breaks, and refilling the refrigerant is as simple as pouring water into a basin.
Indeed, a lot of evaporative coolers even come with hookups to solar panels that can be discretely placed in the yard, so they draw a net of zero electricity from the home when they're running. (Most evaporative coolers don't need to be run at night in the climates where they work at all.)
Ultimately, your evaporative cooler can be a sound investment in the right parts of the country. If you're in the Deep South, nobody, no how, is ever going to convince you to change your air conditioning unit. If you're in the mountain west, an evaporative cooler makes a lot of sense. Think about the options for changing over before the summer comes around and you're looking at yet another sky-high electrical bill for cooling your home.
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