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In a recent University study energy consumption of gas and electric water heaters operated and tested on hard water supplies was measured and compared to measured energy consumption of gas and electric water heaters operated and tested on softened water supplies.
The gas heaters operated and tested on hard water consumed 29.57% more Btu's of energy than the gas heaters operated and tested on softened water for the same amount of energy delivered.
The electric heaters operated and tested on hard water consumed 21.68% more Btu's of energy than the electric water heaters operated and tested on softened water for the same amount of energy delivered.
It is not necessary to heat water to a high temperature to produce scale. Any increase above the original temperature of the water can cause lime scaling to occur.
Although no chemical reaction occurs which causes calcium sulfate to deposit when the water is heated, this hardness mineral is unusual as it is less soluble in hot water than in cold.
Hard water can also be troublesome in industry. In many industrial applications, however, not only must hardness be removed from the water, but all mineral content must be eliminated. Mineral deposits can cause serious difficulties in boilers, air conditioning systems, gasoline and diesel engine cooling systems.
Water is an excellent solvent. Our previous articles outlines how water collects the various contaminants found in it.
As moisture falls through the atmosphere, it absorbs amounts of carbon dioxide (CO2).It also collects amounts of this gas on and in the ground from decaying vegetation. Since carbon dioxide is a product of both combustion and decay it is present in practically all water supplies.
H2O + CO2 --> H2CO3
When carbon dioxide dissolves in water, some of it forms a weak acid called carbonic acid.
This acid is responsible for dissolving limestone or carbonate deposits in the earth. It also produces certain types of corrosion in water and steam lines. The natural solvent action of water is enhanced by carbonic acid making it even more effective in dissolving hardness minerals.
Hardness minerals-calcium and magnesium are in plentiful supply. While they are not found in their elemental form in the earth, they occur in combination with other elements in an abundance of forms. Common calcium minerals include chalk, limestone and marble. These substances are chiefly calcium carbonate (CaCO3)or mixtures of calcium and magnesium carbonates and other impurities. Gypsum is calcium sulfate (CaSO4). In this compound calcium is combined with sulfur and oxygen.
Epsom salt is magnesium sulfate (MgS04).
Ions of the following calcium and magnesium compounds are found in water:
The amounts of these various chemical compounds present in water supplies depend on two factors: