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How Does My Pool Lose Its Water Temperature?
http://www.poolwarehouseuk.com/
Swimming Pools lose heat in a variety of different ways such as convection and conduction, but evaporation through the water surface area is by far the greatest source of energy loss.
Evaporation uses up huge amounts of energy, so to restore water temperatures, that energy has to be put back in to the water. Research conducted by the United States Department of Energy, shows that to raise 0.22 gallons of water up 1°F requires 1 BTU unit of energy. However, for every 0.22 gallons of water, heated to 80°F, that evaporates, 1048 BTU energy is lost. In metric terms, this means that 0.001163 kilo watt hours are required to heat one litre of water by 1°C, whilst every litre of water, at 27°C, that evaporates uses up 1.218 kilowatt hours.
Testing on outdoor pools clearly show how evaporation from the surface area is key in heat loss from the water. Heat Losses: Radiation to the air 20%, conduction lost to the ground 10%, evaporation 70%.
The rate of evaporation from an outdoor pool varies depending on a variety of factors, including the temperature of the water, the temperature and humidity of the air, and the wind speed at the surface of the water. The higher the pool temperature and wind speed and the lower the humidity air temperature, the greater the evaporation rate.
How can this energy problem be addressed? The simple answer is use a pool cover. To gain the maximum benefit from your cover it should be placed over the water surface area at all times when the pool is not in use, and only taken off just before you would like to swim, and then replaced afterwards.
Covers are manufactured in a wide range of materials, offering different weights and colours. However, regardless of the type of cover, they all offer:
Lower Energy consumption by over 50%. Lower chemical usage by up to 60%. Virtually eliminate evaporation by 98%. Increases pool temperature by up to 8°C. Reduce growth of algae. Absorb the heat of the sun. Reduce filtration/pump time by up to 50%. Reduce debris contamination and subsequent cleaning costs.
Types of Covers. Solar covers offer the advantage of solar gain, raising the water temperature, in addition to the evaporation reduction of sealing the surface of the water. These covers are usually used on domestic outdoor pools. A solar cover will usually last for between 5 and 10 years. These covers will therefore pay for themselves over and over again.
Heat Retention covers are usually made using a 5mm thick layer of foam. These covers are very durable and an excellent barrier to evaporation, but they provide no temperature rise through solar gain.
Francis Lowe is a leading expert in swimming pool maintenance with a huge wealth of experience developed from 40 years in the industry.
To see a full range of pool equipment, including pool covers and solar covers please see the website of specialist supplier poolwarehouseuk.com
Article submitted Wednesday, November 30, 2011 & read 8 times.
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