what is the optimum temperature to remove humidity from a room using an ac
This LG window air conditioner at the BuildingGreen office has a setting that maximizes moisture removal.
Last week, I addressed strategies for controlling wet sources in homes during the summer--1 of the contributors to discomfort during hot humid summers. This calendar week, I'll examine how to remove unwanted humidity using air-conditioning equipment, starting with some fundamentals. To understand moisture removal, it'southward important to brush upward on a bit of physics. Air is able to hold only a finite amount of h2o vapor, and that amount is governed past the temperature of the air. Warm air tin hold more than moisture than cool air. This is why water aerosol appear on that cold glass of iced tea: the outer surface of the glass is cold so the air shut to the drinking glass cools off and the amount of moisture information technology tin can hold drops. When that air temperature cools to the "dew point," information technology means that 100% "relative humidity" is reached; as information technology cools further, water vapor in that air "condenses" out equally liquid water. (Relative humidity is the amount of h2o vapor in air, expressed as a percent of the full amount of water vapor that air could agree at that temperature.) The higher the relative humidity of the air, the higher the dew indicate temperature. On a really dry mean solar day (low relative humidity), not much condensation will form on that glass of iced tea, while on a day with 90% relative humidity, condensed h2o will baste down the glass and puddle on the table it'due south sitting on. All this is important to know, relative to moisture removal, because that'due south exactly how most mechanical air conditioning systems work. (I'll encompass dehumidifiers next week.) Copper coils in these systems carry cold refrigerant (rut-transfer fluid), and as household air is blown by these coils, moisture from the air condenses onto the coils and is captured.
Air conditioners and wet removal
Standard compression-wheel air conditioners (both window units and whole-house models) remove moisture through condensation, as described higher up. Their effectiveness at wet removal varies, however. Moisture-removal is reported several means. On product literature, pints per hour or liters per 60 minutes is usually listed. A modest-sized, 12,000 Btu air conditioner, for example, such as the LGmodel in the BuildingGreen office that'south pictured here, typically removes between 3 and 4 pints of h2o per 60 minutes. Unfortunately, every bit the energy efficiency of an air conditioner goes up--college EER (energy efficiency rating) or SEER (seasonal energy efficiency rating)--the wet-removal functioning usually goes down.
A special "dry" setting that maximizes moisture removal on this LG air conditioner can aid in humid weather.
Dehumidification efficacy is likewise measured by the "sensible heat ratio." (More terminology, I'm agape: "sensible heat" refers to free energy associated with a change in temperature; "latent rut" refers to energy associated with a change in stage, such as from vapor to liquid--which might not involve much modify in temperature.) The sensible heat ratio is the fraction of the full cooling energy used for sensible heat removal. Thus, a sensible heat ratio of 0.eight means that 80 percent of the free energy used by the air conditioner goes toward lowering the air temperature, while 20 percent goes toward moisture removal.
Selecting and operating an air conditioner
To achieve comfort in our houses, nosotros need to both lower the air temperature and reduce the humidity. Selecting air conditioning equipment involves considering the desirable rest between sensible heat removal and latent heat removal. In a very humid climate where lowering the humidity is almost as of import every bit lowering the air temperature, a low sensible heat ratio--say 0.75 or lower--makes sense. In highly energy efficient homes, humidity removal is also often more than of import than cooling (because less unwanted heat gets in), so a depression sensible heat ratio makes sense--or even a dehumidifier, which normally provides no actual cooling.
Success with air workout and moisture removal also involves equipment sizing and performance--information technology gets pretty complicated. If an air conditioner is oversized, it will operate for just curt periods of time, and that will reduce the moisture removal performance. The ideal is to take the equipment sized then that it volition operate fairly continuously during peek cooling periods--rather than switching on and off frequently. It also improves moisture removal to operate air conditioners on a lower setting. Blowing air across the coils more slowly increases moisture removal, so if you're buying a new unit of measurement, look for a model with variable cooling output (or a loftier wet-removal setting). An air conditioner technician or mechanical engineer will assistance you choose the right product for your situation. He or she will considerable the variables (climate, wet sources, cooling loads, etc.) and suggest a solution that makes sense. Don't forget that the less you use an air conditioner, the lower your energy bills, so pay attention to the unproblematic strategies for reducing cooling loads and decision-making moisture that I've covered in the past two weeks.
Alex is founder of BuildingGreen, Inc. To continue up with his latest articles and musings, y'all tin sign up for his Twitter feed.
(2010, July 20). Removing Moisture from Homes with Air Conditioners. Retrieved from https://www.buildinggreen.com/news-article/removing-moisture-homes-air-conditioners
Source: https://www.buildinggreen.com/news-article/removing-moisture-homes-air-conditioners
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